83 Nautique 2001 - Mercruiser Chev 350 260 issue
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=40448
Printed Date: April-28-2024 at 1:54pm
Topic: 83 Nautique 2001 - Mercruiser Chev 350 260 issue
Posted By: geecee
Subject: 83 Nautique 2001 - Mercruiser Chev 350 260 issue
Date Posted: January-24-2017 at 11:19am
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Hello everyone, My engine recently developed a slight knocking sound, didn't notice any major performance issues but did have a lot more people on the boat that usual so I was revving higher for normal speeds. Anyway to the point, I did a quick and nasty compression test, I can't guarantee the accuracy of results but they are roughly as follows. I just did a dry test, 1. 135 2. 145 3. 115 4. 130 5. 95 6. 125 7. reads +/-50 if i zero and try again needle doesn't budge 8. 150 So other than the fact that there is quite a bit of inconsistency, cylinder 5 and 7 and clearly a problem, 5 specifically. Also I'm not a mechanic, but am quite technical and hands on, if I just have broken ring/s could this be a quick fix or am I in for a full rebuild? in your opinions? Now this engine no longer has the serial plate on, does anyone know if there are major differences between the 78-82 Mercruiser 350 260hp and the 82-86 Mercruiser 350 260hp engines in terms of internals, as being an '83 model I assume it could have either range installed (almost 100% sure its still factory engine after discussions with Art) ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Replies:
Posted By: GottaSki
Date Posted: January-24-2017 at 12:15pm
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Don't blame your loading or revs, these engines can take it all day. If something weakened, then its an eventuality, it was going to happen. 5 and 7 are adjacent, so that may be indicative.. Best take the head off and look at the jug and the slug, and the head gasket. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: geecee
Date Posted: January-24-2017 at 12:24pm
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100%, thanks for the reply Will have to find a buddy with a nice big garage that I can abuse :D not ideal timing with a trip planned for weekend after next ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: GottaSki
Date Posted: January-24-2017 at 12:40pm
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Very good. Though i don't see a garage required, unless to escape extreme heat or something. Consider, to not risk futzing with breaking exhaust manifold.bolts, just take the head off with it.. If it turns out to be just the head gasket, it can go right back on. If its a valve or worse, then separate the manifold from head. An hour with with a socket set after work, you will have your answer if an $80 gasket set will get you motorboatin, or if its something more serious, then plan B. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: geecee
Date Posted: January-24-2017 at 12:43pm
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Do these marinized motors require different gaskets as apposed to standard engines? ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: January-24-2017 at 12:48pm
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google told me I need a stainless gasket ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: backfoot100
Date Posted: January-24-2017 at 3:53pm
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I agree with Gottaski on the next steps. Minimal time/effort to determine where to go after that. There are technically marine gaskets but they really aren't needed. Many have used standard auto gaskets without issue. I personally used a marine head gasket for my rebuild and then used standard gaskets for the rest.. Some others might disagree. One exception is if you're using it in saltwater. Then definitely want to use marine gaskets. As for your original question about any changes through the years listed for the SBC. They are minimal but may/may not cause issues. 79 and prior had the dipstick on the port side with two piece rear main seal. 80-85 moved the dipstick to the starboard side with two piece RMS. 86 still had the dipstick on the starboard side but changed to a one piece RMS which changed the crank flange and oil pan. '86 cranks and oil pans will not fit on 85 and older blocks. As such 85 and older cranks and oil pans will not fit on 86 blocks. All the rest of the internals should interchange. If that is truly an 83 and the factory motor, I gotta believe it will be an 83 block. I just can't imagine a ski boat manufacturer putting an older overstock engine into their boat without some potential consumer fraud backlash.. No way in hell a factory 83 boat would have an 84 or newer engine unless it was changed out somewhere along the way. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: TRBenj
Date Posted: January-24-2017 at 4:09pm
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It's pretty normal for marine engines to lag behind a year or sometimes more, comparing block castings to hull model year. Remember that there is a 3rd party supplier (marinizer) that has to do their thing. Boat production is also nowhere near the clockwork precision of auto production. Then there are special cases- like how Jody just told us recently that Ford stopped production of the 351w in '97 but PCM/correct craft horded enough parts to keep selling GT40's through 2002. Long story short, verify casting numbers to be sure what you've got! |
Posted By: Riley
Date Posted: January-24-2017 at 5:02pm
Eddie, that may be the case now, but was common on older boats. My brothers and I bought a Century Resorter in 1981 and it has a Mercruiser 255 in it which according to the Merc serial number is a 1977 engine. My BIL's 1988 Malubu Skier has a 1987 PCM 240 hp engine based on the engine serial number. The boat is an '88 according to its serial number. Correct crafts, especially older ones might vary several years from when they were built, when the motor was built and what the bill of sale stated was the age. |
backfoot100 wrote:Posted By: backfoot100
Date Posted: January-24-2017 at 5:41pm
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OK, I stand corrected. You guys would certainly know more than I do. My limited knowledge comes from mine and John's boat. Both are '86 and both are definitely '86 MY engines. Now, that may be because of a couple of factors. First off, both are American Skiers and had a limited yearly build number compared to CC's. Maybe A/S demanded same MY engines? I don't know. Just thinking out loud. Next time I talk with Ron Tanis, I'll have to remember to ask him if that was even a possibility. Second, both have (or had) limited production HO engine options. One an Indmar and the other is a Hardin. Both a far cry from a standard production PCM or Mercruiser. This point is probably the real reason that the MY matches hull and engine. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: Riley
Date Posted: January-24-2017 at 5:49pm
| I was in my early 20's when we bought that Century and I was pretty surprised when I found out that it had a 1977 engine, especially as all the '81s at the time were advertised as 260's and ours was a 255. I asked the dealer about it and was told that was "normal" . Today, you could probably make a stink about that. |
Posted By: 8122pbrainard
Date Posted: January-24-2017 at 5:53pm
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Regarding block casting dates there was a time when cast iron was left out in the weather for 1 to 3 years to "season" the casting before machining. The "seasoning" would equalize any stresses from the casting. During WWII they didn't have the time but after up until I'd say the late 60's when casting improvements were made, the seasoning was very common. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: geecee
Date Posted: January-26-2017 at 2:19am
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thanks everyone, now to decide if I want to take on pulling the heads myself or pay someone else to do it. I have worked on bikes before but never more than single cylinder work ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: MrMcD
Date Posted: January-26-2017 at 4:27am
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With 5 and 7 down on compression it does indicate a blown head gasket. It is possible that two cylinders side by side have valve or ring trouble but more likely a blown head gasket. When you pull the head study the head gasket and take pictures. If you can read a gasket it will tell you a lot about what failed but either way the head comes off to fix it. With the Manifold off I would do both sides at once. Since the heads are off a machine shop could inspect your heads for cracks and this would be a good time to have them rebuilt just to make sure you are good to go. The poor mans test to see if all your valves are sealing in the heads after you pull them would be to tilt the head so the ports face straight up. Pour some solvent in each port, intake and exhaust and watch for seepage. None of your valves should leak but if they do you will see the leak right away. If you do this outside you can test with gasoline but solvent is safer gasoline fumes are dangerous . ------------- |
Posted By: geecee
Date Posted: January-29-2017 at 1:14pm
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Thanks everyone for any info. Pulled the head today, actually pulled exhaust manifold and everything off, no stripped bolts thank goodness. (Actually one was pretty loose come to think of it) Attached a photo of my head and gasket, the problem cylinder (7) you can notice a different colour to the valve (far right valve), also the valve is smooth and does not have that recess that the others do, is this normal? No noticeable blow through on the head gasket between cylinders, there was some water going through by the head bolts though. previous owner seemed to patch this with some silicon in the bolt hole  . No water in the oil however.  Cylinders seem pretty clean, no major wear on the walls that I can tell with my untrained eye, very slight scoring but can only just feel it with bare fingers. No noticeable play in pistons. I will take the head through to my local mechanic if I get a chance and get his opinion but any thoughts from anyone here as to what my problem could be? ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: Duane in Indy
Date Posted: January-29-2017 at 2:45pm
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I prefer a leak-down test over a compression test any day. You can loosen all the rocker arms (which will close all the valves) and check at BDC. That will let you hear and see leaks much better. If it is leaking between bores it will be evident with air leaking out the adjacent plug hole. Usually you pump 80 psi into the gauge (adjusting the inline regulator to read 80). The air then goes thru a valve to a small orifice and then into the plug hole. The second gauge will measure the amount of air inside the cylinder. IF the leak is larger than the orifice size then it will register something less than the 80 psi on the second gauge. First gauge shows line pressure and the second shows cylinder pressure. Just my way of checking. ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: geecee
Date Posted: January-30-2017 at 5:01am
my mechanic is going to swing by today and have a better look for me, might be pulling the engine soon and dropping it with him to work on  right in peak season here------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: Duane in Indy
Date Posted: January-30-2017 at 9:53am
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Interested to hear mechanics view. Gasket and head look more suspect between the two center bores than anywhere else. Normal trouble area when two exhaust valves are together. With the heads off it is good time to freshen them up anyway. Oddball valve proves this is not the first time it has been apart. Definite YES to FelPro gaskets. Looks to be a FEL17030 gasket ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: geecee
Date Posted: January-30-2017 at 10:01am
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Time wise felpro is not an option right now, as for me it will be 3 weeks just to get the gaskets in. Shipping is also about the same price if not more than the gaskets themselves. Mechanic confirmed middle looked suspect but also not the reason number 7 has no compression, He suggested I do a quick valve test with some solvent to see if I have a valve leak on that cylinder. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: January-31-2017 at 1:50am
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Mechanic had a look at the engine, said on general inspection he cannot see anything major that would cause an issue, the bore and pistons all seem good, really minimal piston slap etc. I did the solvent test and 3 of the 4 had leaking valves and 7 did seem worse than the others. Inherently this could be my issue too. He did say that on these older cast blocks there can be issues with the head gaskets. He suggested I get it skimmed and the valves etc checked by an engineering shop and put it all back together. worst case I waste a head gasket if it doesn't solve my problem. If I still have an issue we will pull the motor and look at a full rebuild. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: January-31-2017 at 6:23am
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Okay engineer says valves are biggest spec already and the head is in pretty bad shape. Are these just standard chev 350 heads? aka I can find one off a car and slap it in ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: Duane in Indy
Date Posted: January-31-2017 at 7:24am
Skim cut like he said and grind valves and seats. New valve seals and put them back on. Note: I said "them". Do both heads ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: geecee
Date Posted: January-31-2017 at 7:53am
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The idea was to do both heads but to get this one on asap to see if it's a bigger problem before I spend unnecessary money. Unfortunately with living this side of the world parts are a lot more expensive and a lot harder to come by than that side of the pond. Busy trying to find a set of replacement heads now and even that is posing to be a bit of a problem. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: Bri892001
Date Posted: January-31-2017 at 11:09am
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Just going to throw one thought out there. You mentioned above that when you were removing your exhaust manifolds, that at least one of the bolts was already loose. Is there any chance that this slight knocking you hear was an exhaust manifold leak? |
Posted By: MrMcD
Date Posted: January-31-2017 at 11:08pm
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Take a Mic and measure the thickness of the head gasket at all the hot spots, normally the hot spots are close to the exhaust valves. It does indeed look like your gasket failed between the center cylinders. If the gasket measures smaller in certain areas the engine was overheated at some point and crushed the head gasket. You are looking for a difference in thickness of .003 -.004 normally from crush. This crushed area will fail later after the overheat. Could be 1 day or 2 months but once crushed the gasket will fail. The head bolts in the same area are usually low on torque when you remove them again from the crushed gasket. The gasket can't rebound from a crush. Make sure your head is still flat with a straight edge before assembling again or have a shop rebuild the heads. A leaking valve can quickly be found by pouring solvent in the ports. If it escapes past the valve it is not sealed. When you have hot spots or localized overheating the block and head expand, this is what crushes the gasket. Once the block and head cools the gasket remains crushed but the block and head go back to original size leaving the head bolts in that area loose and the gasket will blow. ------------- |
Posted By: Gary S
Date Posted: February-01-2017 at 12:01am
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Mark would that be caused by running lean? It looks like with the Chevy design with the two exhaust valves being next to each other could cause trouble, It also looks like the sealing surface between the two cylinders on a Chevy is thinner compared to a Ford too. Now I have to find a pic of a Chrysler head to see their take ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: geecee
Date Posted: February-01-2017 at 1:31am
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So the head is being rebuilt today, Engineer says he will get it right but because the head is so worn I should look for another set to replace these with. New gaskets etc and torqued back to spec, hoping I get it back this afternoon then I can get cracking at assembling this evening, hopefully test and soon find out if that's related to my compression issue, holding thumbs. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: February-01-2017 at 1:35am
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For those interested the area on the block where the valve seats was really badly pitted, even I could tell they were looking horrible after they had cleaned up the head. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: GottaSki
Date Posted: February-01-2017 at 11:26am
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The burn looks very normal to me, but I just don't understand this 'head is worn' thing.... No cracks, seats, guides, valve grinds, lap, resurface, thats about it. But from very afar, the head gasket appears odd at 3 oclock on # 7 ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: MrMcD
Date Posted: February-01-2017 at 1:40pm
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If you check this posters location you will see he lives in South Africa. What is available to us and common may be unobtainable for him. Gary, lean burn is a common cause of local heating and gasket failure. Overheating does the same thing. The hottest areas grow the most and crush the gasket. Fel-Pro offers a nice chart showing how to map a gasket and record the measurements to show what area's have been crushed. Once you do this you know exactly what happened in what cylinders.. It is a nice tool to help search for the failure area. This is a boat with a raw water pump. Many times we see old impeller pieces lodged far inside an engine blocking water flow. Worth ruling out before the new parts install. It is horrible to do all this work and have the exact same failure again because the cause was not identified. Mark ------------- |
Posted By: backfoot100
Date Posted: February-01-2017 at 1:45pm
Ironically, I was thinking exactly the same thing. You need to explain "the head is worn". Then I keep looking at #7. In addition to the little burn at 3 o'clock on the gasket and the aforementioned exhaust valve that has obviously been replaced already, the intake valve has some weird flash or heat scoring on it. Like maybe starting to get on the lean side and started to frag the plug. The flash scoring even looks to be originating from the plug. What did the plug look like on #7 when you pulled it? How did it compare to the rest of the plugs? ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: geecee
Date Posted: February-01-2017 at 1:56pm
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Thanks for the insight. My wording perhaps is not 100% here, also I don't know the correct terms as to the areas on the head etc. The area where the valve seats is badly pitted, engineer used the words badly corroded. My valves are already the biggest you can buy and there is a tiny bit of movement here, should be okay for now, but any more wear and I will have a bit more of an issue. Impeller was still in okay nick when I got the boat, it was the first thing I changed in any case (housing and impeller), did find some bits of rubber throughout the cooling, obviously from a previous impeller which I pulled out as best I could. Motor runs cool when on the water, I always keep an eye on the gauge. Plugs on 1 and 3 looked semi dry 5 and 7 were wettish. Plug gaps looked pretty consistent all round. I bought new intake valves today, there was enough meat on the exhaust valves for him to clean up and reuse, the head was getting skimmed when I dropped them off, I should have it all back in the morning. edit: had a closer look at the head gasket, that part at 3 o'clock on 7 does look a little suspect, has some discolouration on, it has become a bit damaged with me carting it around to get a replacement, so I don't think mic'ing it at this point would lead any useful results. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: mark c
Date Posted: February-01-2017 at 7:19pm
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So your guides are wearing out (the cylindrical part of the head that the valve slides up into). Those can be knurled to tighten them up, but its a temporary fix, they can also be sleeved with a brass sleeve. Doesn't cost all that much here in the states but might over in SA. The valve seats (the corroded part) are replaceable, they can be popped out an a new one pressed in and then cut to match your valve face. Again not a big deal here but who knows where you are. also those aren't the biggest valves you can install. Those are 1.94" intake, 1.5" exhaust valves. Biggest you could put in there (without going crazy with extra machining costs are 2.02, intake and 1.60" exhaust. Probably not worth the effort though based on the normal operating RPMs of these boats. You wouldn't see any real performance gains over the stock set of heads unless you were running the engine above 5K RPMs. And yes those heads are exactly the same as any late 60's to early 90's small block chevy heads with the 4 bolt valve covers from just about any GM car or Truck of the era. 99.9% of them will have the 1.94/1.5" valves and 76cc combustion chambers. You might get a slightly better set out of an L82 corvette, but again unless that the first set you find, performance wise its not worth the extra money someone would probably ask for them. . You don't want to go out and get a set of Vortec heads (which came out in the mid 90's) with the valve cover bolts down the center and a heart shaped combustion chamber, They require different intake and exhaust manifolds than your normal small block chevy heads. |
Posted By: KENO
Date Posted: February-01-2017 at 7:44pm
Mark If you were to do this you'd probably figure out that the old exhaust manifolds will bolt right on to the 5.7 Vortec heads 
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Posted By: mark c
Date Posted: February-01-2017 at 10:50pm
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They will indeed bolt up, but the bolt hole locations on the vortec heads in relation to the port will move your exhaust manifold up just a bit, somewhere between an 1/8th and 3/16" so depending on how much meat there is on the exhaust manifold and marine manifolds seem to have a ton you could get a leak along the bottom of the manifold and poor port matching. Probably won't leak but I've never had a reason to install Vortec heads on any engine I've ever built or even owned. The stock valve covers are also 1/2" higher than a standard set of SB chevy heads, again don't know if this will interfere with any of the SB marine exhaust manifolds, Bolting them up will be much simpler with 4 bolts down the center, don't have to worry about dropping one down between the valve cover and the manifold. Combustion chambers are 64CC so a flat top piston compression ratio will increase to just about 10:1 (probably closer to 10.2) and piston quench would be somewhere in the .044 range assuming a stock composite type head gasket and the rest of the engine being basically stock and never had the block decked, which is just a bit to much quench height. All of that will put you right in the premium fuel zone. |
Posted By: geecee
Date Posted: February-02-2017 at 12:47am
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Thanks mark 👌🏻 In my general vicinity we have 1 shop that sells V8 spares, they are very knowledgeable and helpful albeit a little pricey but they have the market cornered so that's just business. They did mention doing something to the guides to give them a bit more life, but I can get a 'good' second hand set of heads for about $300 which considering what I just spent on gaskets and valves really seemed reasonable. Unfortunately here V8 engines aren't as common as over there, and as soon as I mention reverse rotation or marine everyone's faces go blank ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: Duane in Indy
Date Posted: February-02-2017 at 7:15am
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Don't know all about shipping and import fees but these might be worth looking into. Save 40 or more pounds and wake up that SBC some. Post this number in the E-Bay search line: 291996169160 And for Ford fans, try this one: 351880220666 ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: geecee
Date Posted: February-02-2017 at 7:34am
Not a bad price that, freight is $120 still way cheaper than I have been quoted for a new set here, slightly more than half the price of local supplier. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: KENO
Date Posted: February-02-2017 at 9:45am
Well back to my comment about them bolting right up, I helped a friend swap a later vortec into his boat and they bolted right up and no leaks or issues of any kind. We did change risers to some 3.5 inch ones but saw no sense in changing the manifolds and I seem to remember nobody made a set specifically for 5.7 Vortec heads anyways because the older ones worked., |
Posted By: TRBenj
Date Posted: February-02-2017 at 10:03am
| No differentiation vortec vs non-vortec on SkiDIM's site (they sell Pcm chevy manifolds). Interesting. |
Posted By: backfoot100
Date Posted: February-02-2017 at 10:35am
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It's a pretty common upgrade to put Vortec heads on an older non-Vortec engine. The results are about the same as putting GT-40P heads on a SBF with the exception being a new intake and valve covers are required but have never heard of needing new manifolds or headers. I'm sure someone in the hot rod and trucking communities would've mentioned something to that effect a long time ago if it was required, or at minimum it would've been mentioned in the probably dozen or so tech books I have specifically on building and modifying SBC's. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: TRBenj
Date Posted: February-02-2017 at 11:54am
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Couldn't find anything in an hour searching google re: different exhaust bolt pattern/port alignment with vortec heads. Definitely true on the intakes (sounds like there are some catalog gm vortec heads that offer both intake bolt styles- but the old style intake ports don't align). I'd like to hear more about this, as vortec seems like a good way to go (if you're stuck with chevy power, of course).
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Posted By: JoeinNY
Date Posted: February-02-2017 at 12:18pm
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Yeah we put a vortec Tahoe engine into a buddies Malibu a year a go with just an intake swap... he also went to a dui at the time to avoid any issues with non optimized mercruiser electronic ignition/engine nanny controls but I don't think that was required. Makes a junkyard roller cam vortec engine a pretty cheap swap for a later model 1:23 to one boat ... if you are into that sort of thing. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: backfoot100
Date Posted: February-03-2017 at 8:28pm
It's a solid upgrade and pretty cheap too. You can find Vortec heads very reasonable out there. The articles make it seem the reason for the intake change is the new bolt pattern but the Vortec intake ports are much taller than the old version. They flow a ton better over the entire RPM range. Then the smaller heart shaped swirl ports bump the CR a little. The one downside is you also need new valve covers as they bolt through the center instead of around the edge. Good and bad thing IMHO. The center bolts seal better and it's much easier to remove the covers if you have to but cosmetically, I still prefer the old style. I'm pretty sure that the new covers are also taller too. Leaves enough room for roller rockers without a problem. I don't recall for sure if you can reuse the old pushrods. I'm thinking not but I would have to revisit that to verify. Overall, the end result would easily match what is achieved with GT-40P's and an intake on a SBF. The cost of the upgrade would probably be more than a similar SBF upgrade but only because of the valve covers (and possibly the pushrods) that are needed. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: mark c
Date Posted: February-04-2017 at 12:01pm
| Stock vortec heads also have a valve lift limit of .450 inches due to the height of the taller valve guides and the heavy gauge valve springs which will cause coil bind. The retainer will hit the guide before the coils physically bind. Guides can be machined down and of course the aftermarket vortec heads may or may not already have the guides shortened depending on who manufactured them. Don't know what cams are out there for a RR SB chevy, but be aware this may or may not be a bolt on mod. They are good heads, about equal to the old Fuelie 202 chevy heads with a better chamber design easily capable of 400HP on a fairly tame build if the quench heights are set right. |
Posted By: geecee
Date Posted: February-05-2017 at 1:11pm
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Popped head back on with new gaskets, set the rockers and turned her over, had full compression on all cylinders, Connected everything back up and fired her up, didnt go, but that was our fault, didnt check ignition timing, fixed that and she fired up and purred, still had a slight tapping sound, but otherwise smooth and idled great. Headed out this weekend to camp out and took the boat with, did a few runs, the boat seemed to be smoking (white smoke) far more noticeable that I had ever seen, thought it may be oil from assembly so shrugged it off (it had a slight smoke at WOT in the past, but I never run that speed), got the better half up on skis for her first time  Boat developed a small miss at low revs, so we took her out to feel and check perhaps the ignition timing wasn't quite right, temp seemed high, suspected loose wire on the temp transducer, but sorted that and still seemed odd, while i was out felt the gearbox was slipping, so topped up the oil there and soon after I heard a strange almost sucking sound, Tried to turn her over and no go, pulled plugs and water came out the cylinders We religiously torque everything to spec and triple checked every bolt, made sure it was all perfect and tightened in the correct sequence over a three stage torque process. Right now, I am considering picking up a reman merc assembly off ebay, shipping included it may come in cheaper than a local rebuild, and prbably more reliable, also not sure who I could trust locally with a rebuild of this motor, as not many V8s around and also virtually no marine, let alone reverse rotation. Any other options ?! anyone got a nice low hour engine they can crate and ship me as scrap  ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: KENO
Date Posted: February-05-2017 at 3:44pm
How many cylinders had water come out ? Which ones? Was there water in the oil ? It sounds like you only took one head off and had it skimmed. How much was skimmed off of the head ? However much was taken off, your intake manifold to head sealing surfaces aren't parallel anymore and if enough was taken off that one head you could have sealing issues with the gasket Was the new head gasket the stock thickness or different thickness.? Did you use RTV around the water passages in the intake manifold gasket. They're typically tough to seal and RTV is just about always recommended. Did you have the riser off of the exhaust manifold? Lots of questions for ya' but I suppose the logical thought is that it was caused by something you and/or the machine shop did since you didn't have any water issues at the beginning of this thread |
Posted By: GlassSeeker
Date Posted: February-05-2017 at 5:12pm
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I feel sorry for folks any time the dreaded water in the he motor happens... It's never clear where it got in...You spend time and money only to be frustrated again and back at square one. Well if you are not afraid of being too deep$ in the boat your sanity and joy can be restored with a mercruier complete engine...All new... I got the 350hp 383 stroker and it's been plug and play awesome ever since ------------- This is the life |
Posted By: Bri892001
Date Posted: February-05-2017 at 5:12pm
My brother had a similar thing happen after replacing his Chevy Mercruiser heads with a new set of machined ones. If the heads come out a little "shorter" after machining, it does change the way the intake manifold aligns. I believe his solution involved different gaskets. |
Posted By: tryathlete
Date Posted: February-05-2017 at 5:19pm
| So sad to hear that an assembly mistake causes so much agony like this. I cannot imagine the frustration. Makes you want to go find a deep spot and pull the drain plug! Ugh! |
Posted By: KENO
Date Posted: February-05-2017 at 6:13pm
Thinking about this some more, lots of white exhaust smoke, water in some cylinders and that "strange sucking sound" seems to make me think head gasket or cracked head or bad exhaust manifold. Whatever cylinder{s} had water in them should have shiny clean spark plugs compared to those that didn't have water. Not the end of the world, but like these other guys said, it could be a pain in the butt to figure out, but give some answers to the questions in my other post and somebody will have the solution for ya
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Posted By: geecee
Date Posted: February-06-2017 at 1:30am
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1 and 7 had water in, so the outside two, Hearing this I could guess that intake perhaps didn't seal properly, but the motor really felt smooth when we first took her out. I did put sealer around any areas with water chambers, but maybe it wasn't enough. I haven't checked the oil again but when we were on the water it was still clean. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: February-06-2017 at 2:09am
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I'm am really concerned about getting someone local to rebuild this engine. Right now I am considering a crate motor but it will break the bank for me here. I may as well cut my losses and finance a newer boat next option as mentioned is picking up a reman base engine from the states and transferring the exterior items from mine across to the new powerplant. I always suspected a dodgy ring, but with full compression I thought I was in the clear. Now with the excessive smoking i figured it must have a bad ring or two over and above the obvious valve issues I had, I don't want to throw more money at the topend only to find the bottom has issues, so looks like the engine definitely needs to be pulled. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: MrMcD
Date Posted: February-06-2017 at 2:37am
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Your block could be good for more miles if the heads are fixed. You may be getting water into the engine through your exhaust if the manifold is going bad. I made a set up that allowed me to pressurize the cooling system on my brothers boat searching for coolant leaks, I was going to pull the heads. The engine held 35 PSI of pressure for 2 days with no leak so I learned our problem was coming in from outside putting water in the cylinders. You can plug all the exit hoses to seal the engine and make a contraption that allows you to pressurize the engine to see if you have an internal leak. Both exhaust hose coolant inlets need to be plugged. and pressurize from the coolant inlet where water enters your engine. Be careful not to use too much pressure, cars run at less than 20 PSI. If you pump it up to 60 psi you might blow out gaskets that are currently good. I think my 35 PSI test was about as high as you should go. I picked up parts for my test at the local hardware store. I don't have a picture of the boat test but this is on my wifes BMW, same set up I used on the boat.  ------------- |
Posted By: geecee
Date Posted: February-06-2017 at 2:53am
Engine is still together currently. Valves stem seals were replaceed when head was done. What tests can you recommend? Also if anyone knows the best way I can get this water out without stripping the engine or doing further damage ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: February-06-2017 at 2:58am
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I was tempted to get new heads, but also worried about throwing more money at the problem without knowing root cause. Heads would save me a heap, but may not fix the initial reason I looked into the motor, which was a sound I can only describe as a loose tappet sound, That's when I did comp test and found no compression etc. In hindsight I should have done both heads together, but was hasty as I wanted to use the boat this weekend just gone. Thinking about this now, if my valves have a bit of play because there was wear on the head by the valve guides, could this also allow excess oil to be burnt off. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: MrMcD
Date Posted: February-06-2017 at 3:03am
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In the photo above and not seen is a ball check valve which allowed me to close off the hose I used to pressurize the system. Once I had it at 30 PSI in the photo I closed the valve and walked away. After an hour when it was still holding pressure I sprayed all the fittings and connections with a mix of dish soap and water. I found a couple of very slow leaks at the connections, The soap and water will bubble where the leaks are externally. I also sprayed around the intake manifold ends where I know the coolant passages are. When I had no more external leaks I pumped back up to the full 30 PSI sprayed everything again and left it for 2 days. I was still holding pressure. so I know the heads, intake manifold, head gaskets and block are sealed. Then we fixed his exhaust manifold, ------------- |
Posted By: KENO
Date Posted: February-06-2017 at 8:52am
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If there's no water in the oil your water passages in the manifold are sealed good because if they leaked, the water gets directly into the oil You could have a crack in the head above the intake or exhaust valve in the #1 and 7 cylinders, leaking head gasket or bad manifolds. If the machine shop had the valves out, they should have been able to find this. With cracks like this the water leaks into the combustion chamber when the valve is open . You said you had lots of white smoke, my guess is that it was steam from the water in those 2 cylinders What did you use for torque values when you put the head on? Turning the engine over with no water supply and the plugs out should blow the water out of the cylinders, then squirt some oil in and do it again. if you test the system like MrMcD said you should be able to locate the issue |
Posted By: KENO
Date Posted: February-06-2017 at 9:27am
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I'm sure you know the conversion for ft-lb to n-m but figured I'd mention it anyways first increment 25 ft=lb equals 33.9 n=m second increment 45 ft-lb equals 61 n-m Final torque 65 ft-lb equals 88.1 n-m I know somebody named me who has looked at the wrong scale on the torque wrench before and been quite low on torque values so I figured I'd just throw that out there too Thought I was going to 75 ft -lb but really went to 75 n-m which worked out to about 55 ft-lb. Needless to say, I had a little extra torquing to do when I figured that out.
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Posted By: geecee
Date Posted: February-06-2017 at 11:04am
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yes i worked in nm but made sure to use the correct scale. and I believe I got the torque ratings from boxwrench.com but checked a few sources and all were pretty much the same values so I picked one that had both ft lb and nm for me to cross reference ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: tryathlete
Date Posted: February-06-2017 at 3:08pm
| The troubles I read about resulting from fresh water cooling of our exhaust manifolds is almost never-ending. The whole deal makes me wish for cherry red exhaust headers but I suppose there's going to be trouble getting that exhaust out of the boat without creating a burn hazard of some kind to the boat or the occupants! |
Posted By: MrMcD
Date Posted: February-06-2017 at 10:01pm
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I still have a scar on my forearm from a Jet Boat with open Dry Stack headers. Had a carb flooding event on the river 30 years ago in a fast current, busy fixing the carb when a cabin cruiser went by and threw a 3 foot wave at us. The boat rocked and my forearm hit the exhaust. I NEVER want a boat with dry stacks. Took about a 2x2 piece of skin and burned it about 1/8 inch deep. Took most of the summer to heal. Cool exhaust to the touch is a really nice upgrade. I don't care if it costs me some horse power. BTW: we switched that Jet to through the transom exhaust soon after the mishap. I don't think it cost 100 RPM wide open but made it much more pleasant to own. PS: Another cabin cruiser stopped and helped us, he even gave me Gin FIzzes to dull the burn pain. We fixed the carb and went back to skiing. Pretty sure that would not have happened without the Gin influence. Dealt with the burn later. Boaters can be amazing people at times! ------------- |
Posted By: tryathlete
Date Posted: February-06-2017 at 10:16pm
Ouch! So many burns, so many tales--and that's just from cars. Yeah I'd never lift the cover if I knew there were glowing hot headers down there. I wonder what wins--aloe Vera or gin fizzies! I'll take the gin. I met Mike Ditka on a plane once and he said if there's something hurting you real bad, just go back out and play--because the next hurt will make you forget how badly the last one hurt. |
Posted By: backfoot100
Date Posted: February-06-2017 at 10:34pm
I would bet that 90% of the problems you read about are due to owners ignorance by not maintaining little things like impellers and hoses or riser gaskets that start weeping. Losing the cooling water to the manifolds for even a few seconds at any speed above an idle could be disastrous. Then the remaining 10% of the problems comes from improper winterizing freezing the water jacket. Well OK, maybe 9%. There's always exceptions and something can just fail. My point is that premature failure is an extremely small percentage and most of the never ending problems are self induced. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: geecee
Date Posted: February-10-2017 at 1:58am
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Havent had time to even look at the boat this week, but I may have found another 2001 in great condition (from the photos) all original even with the horns on the bow, has the pcm ford engine instead of the mercruiser chevy power plant. hoping to strike a deal next week and see where it goes. better half is a little concerned about having three boats in the yard however  ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: Hercules_ZA
Date Posted: February-14-2017 at 5:00am
Hey Geecee Where in SA are you based?? I have a cracking mechanic who is passionate about the old classics, and doesn't break the bank either. Cheers d |
Posted By: geecee
Date Posted: February-14-2017 at 5:03am
Im hiding in Durban so hard to find decent guys here ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: October-18-2017 at 6:58am
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Okay so the motor is with my new mechanic now. First issue is the impeller failed, this has to have been a full failure as my temperatures have been fine and the impeller was quite new. virtually no fins left on the impeller. Now If I had questionable exhaust manifolds do you think this short overheat could have caused cracks to form or the like which would have allowed the ingress of water into the engine. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: October-18-2017 at 7:09am
 ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: 8122pbrainard
Date Posted: October-18-2017 at 7:23am
I suggest a pressure test to make sure they didn't crack. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 8122pbrainard
Date Posted: October-18-2017 at 7:29am
The unknown is what came first? Did the impeller cause the overheat or did something else cause the loss of water causing the impeller to fail? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: geecee
Date Posted: October-18-2017 at 7:29am
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Yes mechanic will pressure test, but to be honest they looked a little shoddy to me when I pulled the heads prior to the failure. So I'm thinking maybe this added heat caused them to fracture and drown the motor. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: October-18-2017 at 7:33am
I guess so, but as soon as the temp spiked I killed the motor, initially thought it was a loose wire on the temp sensor, after fiddling with the wire I concluded that it wasn't that and that the motor did seem a little warm. Sat for a bit and randomly heard a loud almost suction/vacuum sound, kinda like hitting the bottom of a milkshake. Tried to start it and it didn't turn over, pulled plugs and water came pouring out, ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: Gary S
Date Posted: October-18-2017 at 11:55am
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What kind of raw water pump do you have? I have heard of the Sherwoods cam tearing up the impeller when they get worn but have never seen one do it. They do recommend changing it on a major rebuild. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: geecee
Date Posted: October-19-2017 at 5:47am
Less than a year ago I replaced what was on their with a new Mercruiser pump housing and impeller. The old housing was cracked and impeller pretty shot. One thing I don't have is a raw water filter/strainer in the boat, considering that maybe I should fit one and that may also help with initial possible run dry when first starting the boat as my boat sits out water a fair amount. Not sure if that will even help ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: October-20-2017 at 2:41am
 Latest from my mechanic Piston 1,3,5,7 and 8 show damage from overheating, pistons were installed the wrong way and they used clear silicon to assemble instead of proper sealant. The heads have different casting numbers, so clearly one or both have been replaced previously. They will be pressure testing everything next and I will get feedback on that when they have. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: MrMcD
Date Posted: October-20-2017 at 3:51am
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What I see in your picture of the pistons is a clear case of 4 corner scuff. Indicated by the black marks on the skirt face next to your piston pins. A hot burn condition, usually caused by a lean mixture or bad timing setting heats the piston heads. The heat radiates to the Piston Pin boss. When the boss heats up it will cause the piston skirt to grow in the areas surrounding the piston pin boss. When these areas grow and the engine is still running they start dragging on the cylinder wall. Notice this dragging caused piston skirt scuffing only at the 4 corners and not in the center of the skirts. This scuffing is black and silver, the black indicates oil was present when this overheat happened and burned the oil into your skirts. If this was caused by a engine water temp overheat the pistons would scuff but they would scuff at the center of the skirts not at the 4 corners. You had excessive combustion temperature which heats the piston head not water temp overheat. Causes could be Lean Burn, normally caused by running with a vacuum leak or a lousy timing setting causing excessive combustion temp. If you roll your pistons upside down and look at the bottom of the pistons heads you will see color change from the overheat.. You will need new pistons, The bore will have to be honed again to remove the scuff marks, if they are severe it may need to be bored to the next oversize. New Rings and a gasket set should get you running again. Look closely at the upper halfs of your rod bearings. They may show damage from the pounding. When cylinder temps go this high it normally starts the engine detonating which can beat the crud out of your rod bearings. Better check the heads to be sure they did not warp or crack. This combustion temp was very hot to have this happen. If only one piston looked like this we would have another discussion but with them all looking the same it is very clear what happened. Note: Find what caused this or you may have the exact same issue with the next engine you install. I am sorry this happened and hope you can fix it for not much money. ------------- |
Posted By: geecee
Date Posted: October-20-2017 at 5:13am
Thanks for the great insight. We will be checking everything on the engine and do a service on the holley. We definitely do not want issues going forward. I didn't get into too much detail with my mechanics, but I know they are testing and checking everything. ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: geecee
Date Posted: January-09-2018 at 8:39am
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Need some help again. Mechanic has gone to 40 thou and there is still scoring in the block. he is reluctant to goto 60 thou citing reasons that it can cause overheating etc in motors that are under a lot of stresS? Could anyone confirm or is it safe to goto 60 on these old blocks? ------------- 1983 Ski Nautique '2001' -Chev 350 Mercruiser -Custom Wake Tower -Custom Interior |
Posted By: baitkiller
Date Posted: January-09-2018 at 1:06pm
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Dont know about .60 but I caught what you said about the pistons being in baccerds. I'm pretty sure they are supposed to be baccereds on a RH engine. ------------- Jesus was a bare-footer............. |
Posted By: MrMcD
Date Posted: January-09-2018 at 3:42pm
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The pistons being in backwards will cause no issues at all. Baitkiller is correct for a reverse rotation application. FYI: Drag racers for years have reversed the pistons in some stock class racing because it makes a little less drag which can help at very high RPM. Not good for a Pass Car engine but helps above 4,000 RPM. Boats have a continuous supply of cold cooling water so I would not hesitate to take your block to .060 over if needed. ------------- |