FWC Thermostat Difference???
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Boat Maintenance
Forum Discription: Discuss maintenance of your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=11483
Printed Date: November-17-2024 at 4:41am
Topic: FWC Thermostat Difference???
Posted By: theumer
Subject: FWC Thermostat Difference???
Date Posted: August-05-2008 at 5:38pm
| So my '87 PCM 351 is FWC, and I was looking at getting it to run a little cooler. It runs at 180 right now. I thought a cooler t-stat would be a good idea, but after doing a small amount of research there seems to be a difference between the RWC and FWC t-stats. The one SKIDIM sells for my application is a 170. Because I am FWC do I need to be running a higher temp? |
Replies:
Posted By: nuttyskier2002
Date Posted: August-05-2008 at 7:24pm
|
Theumer, there is a benefit to running a warmer thermostat and that is slightly improved fuel economy. However if your engine was originally equipped with RWC system, there is a difference in piston to cylinder wall clearance in the short block (as opposed to a FWC system). So in this case if you run a higher operating temp, the block will expand more thus increasing piston to cyl wall clearance even more. This could result in more blow-by and slightly increased oil consumption. It certainly won't hurt to experiment a little with the cooler one but I see no need to install the 143* that is commonly used in RWC systems. ------------- 95 Malibu Echelon w/Mercruiser 350 Magnum Skier Former boats: 88 Ski Centurion Tru Trac II 59 Chris Craft Capri (woody) |
Posted By: 79nautique
Date Posted: August-07-2008 at 6:41pm
|
not sure what you two clowns are talking about RWC (Raw Water Cooled) vs. FWC (Fresh Water Cooling) there the same damn thing and use the same t-stat.
Now if you are refering to a closed cooling system on a marine engine that uses anti-freeze vs. RWC/FWC water from the lake then yes closed cooling system will run a higher temp. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: TRBenj
Date Posted: August-07-2008 at 6:52pm
Nope. FWC = Closed Cooling 79 = 
I think Nutty is right- Ive read that FWC boats use the warmer 'stat. ------------- |
79nautique wrote:Posted By: 81nautique
Date Posted: August-07-2008 at 8:15pm
Just for converstaion purposes can it be verified that Correctcraft had two different engines sitting on the shelf depending on what cooling system was going in a boat. I understand the concept of the clearances but find it hard to believe that this was the practice. ------------- You can’t change the wind but you can adjust your sails |
Posted By: TRBenj
Date Posted: August-07-2008 at 8:53pm
I would think that the engines would have shipped from PCM with the cooling system already installed (be it RWC or FWC). Still a valid question though- and I bet youre right that both got the same spec'd marine short blocks from the engine manufacturer. ------------- |
Posted By: boat dr
Date Posted: August-07-2008 at 10:05pm
|
Have to say there is no difference in the spec sheet , be it in "Slang terms" between "open loop and closed loop.
On a EFI engine the temp has to be higher for proper operation of the cold start circuit. But with an older Carb model the temps are not that critical. A 140 will allow a little more advance to be used and sometimes a lower grade of ful before detonation. As far a piston to cyl. clearance these are going to be the same after warm up regardless of water temp.Prove me wrong on that one.......Boat dr.. I am running a 140 at 39 degrees total advance on 89 octane..... ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: 81nautique
Date Posted: August-07-2008 at 11:20pm
Billy, what's the CR on your motor? I've got mine bumped up to 12 initial and 36 total, no knocks at any rpm but I do run high test. My CR is 9.3:1, I also run the 143 thermostat and the boat almost never gets over 160. ------------- You can’t change the wind but you can adjust your sails |
Posted By: boat dr
Date Posted: August-07-2008 at 11:40pm
|
Allen, flat tops and the 63cc heads should give me about 9.75, at least that is what Steve says.
Can run the timing up a tad more if Premium is used but see no need for the cost/ performance diffence.......Boat dr She do not like the Northern gas tho.Boat ran like crap on the High test stuff they have up there. But once home she is happy as a clam with "our" 89 go figure........Billy ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: 8122pbrainard
Date Posted: August-08-2008 at 9:09am
The closed cooling systems are reffered to as "fresh water" cooled in many parts of the country. I've always wondered how these closed cooling systems got to be called a fresh water system. I feel it has to do with running in salt water which isn't considered "fresh" so fresh water was actually put in the closed system. ------------- /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: 79nautique
Date Posted: August-08-2008 at 10:36am
|
always heard it refer to as closed cooling system not fresh water system. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: theumer
Date Posted: August-08-2008 at 5:07pm
i agree that closed cooling system sounds a little less ambiguous than FWC. to clarify i have a heat exchanger and am running antifreeze through the block and running pretty steady at 180 until I start moving through the water. it then drops to around 165 or so. not too familiar with how the heat exchanger system works, but just trying to see if i am running too warm and if that fluctuation is okay....also to add on to my long list of questions  i can't keep my hand on the risers of my exhaust system and heard that means they are too hot???
|
Posted By: behindpropeller
Date Posted: August-08-2008 at 5:57pm
Suuure blame it on the gas!!! ------------- |
Posted By: nuttyskier2002
Date Posted: August-09-2008 at 1:26pm
Doc, you do agree that the marine engines require slightly more piston to wall clearance than "road driven" engines, right? So how much of a temperature difference does it take to require modifying the clearance? I believe it would be worth considering if you were to be putting an engine together and expecting it to last as long a possible. I know that's not what he is doing here, but anytime I make a change, I try to think of any ramifications involved. I look at it this way,.....there is the one size fits all philosophy and there's the build it for it's expected use. Which is better? ------------- 95 Malibu Echelon w/Mercruiser 350 Magnum Skier Former boats: 88 Ski Centurion Tru Trac II 59 Chris Craft Capri (woody) |
Posted By: boat dr
Date Posted: August-09-2008 at 2:49pm
|
Nutty, there are pro's and cons to this line of thinking.My stroker was set up with less clearance than what you would consider safe.
2.5 thousands piston to cyl.is tight in the marine standards but with proper break in it will yield a super long life. Ring gap was aslo a little on the tight side ,002 to the in. of bore.This too can cause a "cold seize" early in break-in if proper warm up is not followed. Mercruiser has been since the early '90s has only removed the exhaust valve guide seals as their sole means of engine work to prepare their engines for marine usage. And there are several out there that have no ill effects from the standard clearances. Not a lot of engine builders go thru the care and time needed to "break in " an engine correctly, so these are the reasons for the excessive gaps used for "marine standards." Kinda like "I will cover my ass thing." Build it loose and it will not seize. This is just my opinion and it comes for free, so consider that if you want a refund..............LOL ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: nuttyskier2002
Date Posted: August-09-2008 at 4:22pm
|
No refunds required! LOL.......Doc, I applaud your professionalism and objectivity. Hopefully one day our paths will cross. I'll buy you a beer! ------------- 95 Malibu Echelon w/Mercruiser 350 Magnum Skier Former boats: 88 Ski Centurion Tru Trac II 59 Chris Craft Capri (woody) |
Posted By: BuffaloBFN
Date Posted: August-09-2008 at 5:33pm
He's an above average fella!  ------------- http://correctcraftfan.com/diaries/details.asp?ID=2331&sort=&pagenum=12&yrstart=1986&yrend=1990" rel="nofollow - 1988 BFN-sold "It's a Livin' Thing...What a Terrible Thing to Lose" ELO |
Posted By: jbear
Date Posted: August-10-2008 at 1:26am
|
I second that opinion Greg...one of the pleasures of going to GL was meeting the dr in person after spending many hours on the phone with him.
john ------------- "Loud pipes save lives" AdamT sez "I'm Canadian and a beaver lover myself"... |
Posted By: 74SkiNautique
Date Posted: August-14-2008 at 11:12pm
|
I have a 150 F thermostat in mine. Its great! When i bought it, it has a 180, too hot for me! ------------- 74SkiNautique |
Posted By: Kristof
Date Posted: August-19-2008 at 9:03am
John, that's one of the reasons I hope the good Doctor will consider to attend again next year...  ------------- - Gun control means: using BOTH hands! - Money doesn't make one happy, but when it rains cats and dogs, it's still better to cry in a Porsche than on a bicycle... |
Posted By: boat dr
Date Posted: August-19-2008 at 12:39pm
|
Karen has a camping spot reserved for us at Hatty Sherwood for '09.Kinda soon to be planning ,,,,BUT............Boat dr ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: jbear
Date Posted: August-20-2008 at 1:18am
|
We reserved our motel room again too.
Hope Moj can do something about the weather! Maybe by next year I can drive Stang's orange boat. john ------------- "Loud pipes save lives" AdamT sez "I'm Canadian and a beaver lover myself"... |
Posted By: reidp
Date Posted: August-25-2008 at 6:37pm
|
I've always used a 160* in mine in fresh, i.e., non-salt water. I dyno'd it and it made 37 more HP than the 143*! OK, that's two lies in one sentence. But I have always used the 160 and always heard that the engine's efficiency, which includes fuel mileage, was a little better with the higher temp, like nutty said. Also, for clarity's sake, the issue isn't that a 160-180 T-stat is a special requirement for FWC'ing, it's that the 143* IS a requirement for any RWC engine venturng into salt water, as the salt really starts to reek havoc above that temperature. Didn't this come up a few years back? ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: Mojo
Date Posted: August-25-2008 at 6:46pm
Fear not JB, there is a strong chance that the reunion will get pushed forward a week in July. This week that we spend with the kids up in GL is always a winner temp and sun wise... As we get closer to the end of the year, Keith will make that determination. Only other way to get warmer water is to go South hahaha 
John, what about the Florida gathering, (see I did not say Reunion) for next Spring.??? We need to talk about that before GL09'.... Drop me a line sometime, I'd like to talk with you about it... Oh, so this is not a thread jack, I have run 160's in both the 76 and the 96' with no problems.. Oh, and my boats suck in lake water, like they're supposed to hahaha.. Moj' ------------- 05' SV211 TE 73' Martinique had:96' SNOB had:76' Nautique had 77 Tique |
Posted By: Hollywood
Date Posted: August-25-2008 at 7:47pm
To the 4th of July weekend? ------------- |
Posted By: JoeinNY
Date Posted: August-25-2008 at 7:53pm
|
I think he means forward into the future giving us an extra week between the 4th and the reunion... ------------- 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: Mojo
Date Posted: August-25-2008 at 8:05pm
|
Forward as in week later.... as opposed to a week back.. Keith's anniversay always falls on the 11th weekend.. He's thinking of moving it to the 18th etc.... Another week can add some warmth and lower winds, but ya never know...
Moj' ------------- 05' SV211 TE 73' Martinique had:96' SNOB had:76' Nautique had 77 Tique |
Posted By: boat dr
Date Posted: August-25-2008 at 8:23pm
I know Karen and I can expect it to really warm up a lot and the winds to die down. Forcast for that week end will be something like this: High temps will be 65/70 {about average} Lows will be 45/50 {Plug in the blanket} Winds below average-15 to 20 MPH Only one tornado forcasted that week end.. Perfect weather for these Southern Rednecks Let me write myself a note: Bring winter sweaters Dry Suits for the sand bar Blue Jeans & thermalwear Sounds like the perfect venue for a boat reunion..................Boat dr ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |