Help - Engine Overheating
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=885
Printed Date: November-22-2024 at 9:41am
Topic: Help - Engine Overheating
Posted By: Guests
Subject: Help - Engine Overheating
Date Posted: October-05-2004 at 10:38pm
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I have a 74' Nautique that has gradually kept running warmer and warmer. She started out @ 140 and was doing fine. Ran for months until I blew an impeler. Replaced the impeler and the t-stat and after that she started creeping up on 160 w/ a 140 t-stat installed. now she is creeping up on 180 and holds at 180 all day. Things I've checked: Raw water pump rotation & impeler install, checked oil for milky haze, Transmission cooler for blockage, oil cooler for blockage, ran it w/o the t-stat, reverse flushed from the raw water to the intake, checked to make sure I have flow @ the raw water pump, all to no avail. Could it be the circ pump? How do I know if it is?
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Replies:
Posted By: jameski
Date Posted: October-05-2004 at 11:43pm
It sounds like you have it narrowed-down pretty well. I guess the circ pump is about all that is left to check. One time I had a circ pump break a blade off of the metal impeller and the blade was blocking the water passage from the pump into the block.
Of course, on the down side, it could be a blown head gasket or a cracked head (or block). A compression check might help diagnose this.
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current boat
http://www.correctcraftfan.com/diaries/details.asp?ID=1977 - 94 Sport Nautique
previous boat
http://www.correctcraftfan.com/diaries/details.asp?ID=601 - 78 Martinique
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Posted By: Guests
Date Posted: October-06-2004 at 2:01am
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Would a blown gasket or cracked have any tell tale signs? i.e. water in the oil?
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Posted By: jameski
Date Posted: October-06-2004 at 8:50am
If you do a compression test on all cylinders, the one with the crack or blown gasket will have lower compression. You would not necessarily have water in the oil.
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current boat
http://www.correctcraftfan.com/diaries/details.asp?ID=1977 - 94 Sport Nautique
previous boat
http://www.correctcraftfan.com/diaries/details.asp?ID=601 - 78 Martinique
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Posted By: Guests
Date Posted: October-06-2004 at 10:24am
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Thanks. One thing I forgot to mention, the exhaust steams (white smoke) when I take off now. Is this a product of the temp being to high or something else.
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Posted By: David F
Date Posted: October-06-2004 at 1:10pm
Chester:
180 degrees is nothing to worry about. 180 is where my '77 runs most of the time. I really do not like it to go below 180 as the engine is less efficient and tighter (tighter means excellerated wear) the colder it runs. Do not get me wrong, excessive heat is worse, but 180 degrees is fine.
The steam you are seeing could be just the result of atmospheric conditions. If the water is cold and/or the air is cool, then steam is normal. One way to elimnate this variable is to run the engine out of water (i.e with Fake-a-lake or similiar) and see if it still steams. Pick a warm day to eliminate cold air causing steam.
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Posted By: 79nautique
Date Posted: October-06-2004 at 3:00pm
You need to perform a cylinder leak test to see if the head gasket is blown. If it is blown it will show up in the oil if it is excessive but if it is still small then it could be burned off in the cylinder and the spark plug would be extremely clean and white in color. I don't really agree with the 180 being ok to run all of the time. 140-160 is normal 180 is a little high to me. I would check the cir pump and also all of the hoses from the haul pick up to inlet of the raw water pump need to be wire re-enforced otherwise they can collapse and restrict the flow of water. also another thought is blockage within the block it self
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: Tim D
Date Posted: October-07-2004 at 4:58pm
When you said blew the impeler, did the blades break off? Mine did it this year,it became hard and brittle and each blade broke off(from not changing it in 8 years). Some were in the pump housing.(I wish I counted them) I took all the hoses off between both pumps looking for the rest. I found three stuck in the exhaust manifolds. And I took the pump off the engine to check behind the pump. There are two holes about the size of a quarter where water goes in the block through the timing chain cover. The circ pump on the enginge can rust with age, I changed mine about 10 years ago because it was leaking, and I could'nt believe it was pushing water because the fins were almost worn away. Also I've heard of the inside breaking loose from the shaft and not spinning, causing the raw pump to fill the engine.
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Tim D
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Posted By: Guests
Date Posted: October-07-2004 at 10:15pm
How tough is it to take off, inspect & put back on the e/manifolds? Do they have to be torqued on re-assembley? This weekend I'm going into the circ pump and checking for blocked passages on the block and exhaust.
(obvious novice)
Thanks for all the help guys, I'll keep you posted.
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Posted By: Ken-Aus
Date Posted: October-08-2004 at 2:36am
I'm with David 180 degrees is far from hot.
mine is FWC and runs 170 - 180. 155 on the hose.
I would suggest that 170 is the ideal temp and 15 degrees either side is OK.
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http://www.correctcraftfan.com/diaries/details.asp?ID=533&yrstart=1976&yrend=1980 - 1980 ski Nautique
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Posted By: David F
Date Posted: October-08-2004 at 1:04pm
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Again, 180 degrees is NOTHING to worry about. An engine runs more efficiently at 180 degrees than anything less. Car engines usually run about 200 degrees or a bit higher. Do not kill yourself chasing 10 degrees cooler...your gauge and sending unit could be off that much. If the temp stays at or below 180 degrees, you are fine!
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Posted By: nms1991
Date Posted: October-09-2004 at 12:17am
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first make sure you are running at 180 degrees and do not have a incorrect gauge, try one of the noncontact thermometer from sears to make sure the engine is running that hot. Any hotter and you start to melt exhaust hoses. Also when does it run at 180 at idle, high speed, midrange?
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Posted By: Guests
Date Posted: October-10-2004 at 12:47pm
Idle = 180 (Before taking out the t-stat on Fri) 160 afterwards
Mid Range & High = 180 before and after removing the t-stat
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Posted By: mrese
Date Posted: October-10-2004 at 4:42pm
Verify that your guages are giving you a good reading by measureing the actual temp of the water. Over time corrosion builds up and that creates resistance. Higher reisistance is what moves that needle to the right. Many people just accept that the guage is reading 10 to 15 degrees high. Turn the ign key to run, disconnect the wire from the temp sending unit, you should get full needle deflection. Then ground it to the block and the needle should fully deflect the opposite direction. Also ensure that someone didn't put teflon tape around the temp sending unit thread to "help seal" the fit. The threads are the ground point on the unit and the teflon often prevents from getting a good ground. The sending units don't fail as often but sometimes they do. You can hunt down the resistance readings for various temps if you really enjoy the journey of trouble shooting.
If you are sure the wires and guage are good, then go the top of this page and click on DIM logo. Go the the FAQ and there is a trouble shooting guide for over heating. You say you verified water flowing at the Raw water pump...., but how much flow? Check out the page. Great info.
With the T stat out the actual engine temp shouldn't get over 110ish. I have also heard from several quality PCM mechanics that 160 to 180 is a good temp as long as it stabilizes.
Sorry for the long post.
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Posted By: Guests
Date Posted: October-10-2004 at 4:55pm
Thanks for the DIM info. One thing it said in the FAQ response that if your exhaust risers are hot your overheating the exhaust. I can touch the risers but I turn loose real quick. They said you should be able to place your hands on the risers but they did'nt say how long.
I'll try the block drain plug tip they mentioned.
Note: Temp Gauge & Sending unit are good.
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Posted By: 79nautique
Date Posted: October-11-2004 at 1:11pm
You should be able to leave your hand on the exhaust manifolds all day long. It will be warm but not to the extent that you have to remove your hand. If you have to remove your hand after 10-15 seconds then it is too hot. And at 180 degrees you will not be able to leave your hand on them.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: Tim D
Date Posted: October-12-2004 at 5:10pm
I fired mine up last weekend in the driveway with the fake-a-lake, checking for leaks after putting the water pump back on. I just happened to touch the by pass hose (just behind the thermostat & goes to waterpump) and it was very warm, pulled it off and stuck a screwdriver in the 90 degree fitting on the intake and felt something soft (not metal). Got a flashlight and found another piece of an impellor blade stuck in there. I didn't want to unscrew it because it would involve taking the distributor off, so a took the thermostat out and with a piece of wire tried to push it out with no luck, so I blew it out with the air compressor. This piece was about the size of a butterbean and was it the very top of the 90 blocking the water flow. The exhaust have very thin passages for water on all sides (to get an idea look at the riser gaskets in a catalog) and pieces of an impellor can easily block water from going through them.
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Tim D
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