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Why use a Thermostat

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=3870
Printed Date: April-25-2024 at 6:58pm


Topic: Why use a Thermostat
Posted By: Bhedbloom
Subject: Why use a Thermostat
Date Posted: June-13-2006 at 6:13pm
This may sound like a trivial question but why do you need a thermostat in an inboard engine?

My Correct Craft engines start and run great without them and the engine temp stays around 85-95 degrees all season long. Folks used to take the thermostats out of there cars for the summer. It seems to me that it would be better for the engine to run at these cooler temps. Any opinions? Thanks!

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Barry, South Carolina



Replies:
Posted By: jimbo
Date Posted: June-13-2006 at 6:53pm
My thermostat went out two years ago and I tossed it overboard and kept right on sking. I asked the board members your same question. The story goes something like this:
The engine is designed to run at a certain temperature range and the tolorances are based on expansion at that temperature. Too hot and things are too tight. Too cold and things are too loose and not sealing correctly. Or something like that. I figure they're cheap enough to not worry about it.


Posted By: Tim D
Date Posted: June-13-2006 at 7:36pm
I think you'll get better "gas mileage" with a thermostat and the motor can probably sweat on the inside if it runs too cool.

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Tim D


Posted By: advsouthwind
Date Posted: June-13-2006 at 11:25pm
the function of the tstat is to allow the engine to warm up before introducing normally colder water to the block. it allows for a more even displacement of heatthroughout the engine, fuel mileage may also be effected by engine temp.   hope that helps

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gave up sea ray life for a 77 southwind 20 project just livin the dream


Posted By: JoeinNY
Date Posted: June-14-2006 at 8:54am
The mileage change is significant, I believe the longevity issue will be significant as well. Its not apples to apples but my explorer needed a new thermostat two months ago, I knew this because all winter I couldnt break 10mpg. When the new thermostat was installed i went back to 16mpg. Your going to get better oil flow and less wear when the engine is up to temperature, and it will run better, go to napa buy the thermostat it will pay for itself pretty quickly.

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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: AWhite70
Date Posted: June-14-2006 at 9:47am
Engines are designed with thermostats for many reasons and starting is not one of them.

It is actually more important that you run a thermostat in a boat than in a car. In a car with a closed cooling system you will eventually get up to operating temperature as long as it isn't really cold outside. In a boat you have an endless supply of 60-80F lake water and you will never warm the engine up.

Engines are designed with thermostats for a reason(s).
1. The tight tolerances engine components are machined to are meant to be run in a certain temperature range.
2. When an engine is run at cold temps for extended ammounts of time components wear faster (i.e. cylinder & ring wear)
3. When and engine is run at cold temps deposits build up leading to poor performance
4. Running cold coolant temps runs to cold oil temps and when oil doesn't get hot enough to cook off condensed water you will build up water in your oil.
5. When oil is cold it is thick, this robs horsepower and reduces efficiency.

In a pinch you won't do any damage without a thermostat for short periods of time (i.e. emergency).....but for crying out loud install a thermostat. The engineers put them there for a reason.

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AWhite70

http://www.correctcraftfan.com/diaries/details.asp?ID=562&sort=revyear&pagenum=5&yrstart=1976&yrend=1980" rel="nofollow - '79 Ski Nautique


Posted By: RobG
Date Posted: June-14-2006 at 11:44am
Running without it may also foul the sparkplugs. I found this out the hard way with my wifes's minivan. (Long story, take my word for it.)


Posted By: Bhedbloom
Date Posted: June-14-2006 at 5:14pm
I,m convinced.....the tstat goes back in! There are two different tstats available for my ford engines. 140 degrees and 160 degrees. Which one would be best or does it relly matter? Thanks for all the help fellow Correct Crafters!

Boating with tstats in South Carolina.

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Barry, South Carolina


Posted By: AWhite70
Date Posted: June-14-2006 at 11:13pm
Original equipment on old CC's was 140 (143 to be exact I believe). Everything in new(er) boats is 160. SkiDIM says PCM now recommends 160 for everything, saying that 143 doesn't allow the engine to get warm enough to cook off condensation.

I have a 160 in both my '79 and '02 and they work great.

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AWhite70

http://www.correctcraftfan.com/diaries/details.asp?ID=562&sort=revyear&pagenum=5&yrstart=1976&yrend=1980" rel="nofollow - '79 Ski Nautique


Posted By: GottaSki
Date Posted: June-15-2006 at 6:44am
Originally posted by RobG RobG wrote:

Running without it may also foul the sparkplugs. I found this out the hard way with my wifes's minivan. (Long story, take my word for it.)


That was likely from the smart fuel injection keeping the mix rich, thinking the engine was still cold.

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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."

River Rat to Mole


Posted By: RobG
Date Posted: June-15-2006 at 12:02pm
GottaSki,
That makes sense. I did wonder how the plugs could get so badly fouled just from running the engine cold. I guess that wouldn't happen with a carbureted engine.


Posted By: 79nautique
Date Posted: June-15-2006 at 12:05pm
it will happen whether it's injected or carburated

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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique


Posted By: p/allen
Date Posted: June-16-2006 at 7:29am
I was thinking that a 140 tstat was for fresh water and a 160 was for salt water . I think I read that in a post a couple of months ago .

Pat

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Pat
http://i175.photobucket.com/albums/w146/72ccfan/100_5977-1.jpg - My 72 Skier
Rock River
Dixon,ILL.


Posted By: GottaSki
Date Posted: June-16-2006 at 9:29am
Thats backwards

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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."

River Rat to Mole


Posted By: wakesurfer
Date Posted: May-08-2008 at 2:17am
My boat constantly runs at 190.

I took the t stat out and it was a rusty and appear to be original...

I am on the fence about the t stat deal.

If so, I will go for a 143.

thoughts?



Posted By: JUST-IN-TIME
Date Posted: May-08-2008 at 3:40am
160 will get the moisture out

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www.switchbait.com


Posted By: backfoot100
Date Posted: May-08-2008 at 11:50am
Originally posted by GottaSki GottaSki wrote:

Originally posted by RobG RobG wrote:

Running without it may also foul the sparkplugs. I found this out the hard way with my wifes's minivan. (Long story, take my word for it.)


That was likely from the smart fuel injection keeping the mix rich, thinking the engine was still cold.


In today's fuel injected engines, a T-stat change of even 15 degrees can significantly change the tuning of the engine. The ECU see's that the engine is running cooler or hotter and adjusts the fuel delivery accordingly to try and correct what it see's as a problem. It's fairly common in some applications to change out the T-stat when you start to mod the engine with things like cold air intakes, exhaust systems, high flow CATS and aftermarket ECU's. It inevitably means less fuel mileage though.

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When people run down to the lake to see what's making that noise, you've succeeded.



Eddie


Posted By: gigem75
Date Posted: May-08-2008 at 12:34pm
carbed engine, it had a stumble on mashing the throttle, noticed it was running pretty cool. Checked and no theromstat, put a 160 in and stumble is gone because the enging is working at the designed operating temp.


Posted By: adamt
Date Posted: May-08-2008 at 5:12pm

Bloom, I went to SouthEast CC here in Orlando the other day to get a new thermostat and impeller. They sold me the 143 degree, I figure they know best.

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-Adam

1973 Skier



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