Trouble shooting Engine Temp
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=48996
Printed Date: November-14-2024 at 11:43pm
Topic: Trouble shooting Engine Temp
Posted By: Otto Throttle
Subject: Trouble shooting Engine Temp
Date Posted: July-05-2020 at 1:18am
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I just changed my impeller and did a 65 mile run the Other day...boat ran perfect. I noticed a temp of 170 degrees....then 160....and around 150. Water temperature was 80 degrees then 73 degrees during the run. Is there a test for the sending unit, the gage, or the thermostat? Engine is cool but it bugs me as it is not working correctly! Thanks! Otto ------------- Otto |
Replies:
Posted By: Jonny Quest
Date Posted: July-05-2020 at 3:03am
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I would first replace the thermostat and gasket. Use a good scraper to remove all the old gasket. They can put up a bit of a fight. Then get an infra-red thermometer “gun” and carry it with you in the boat. Shoot temps at several key places: -intake manifold water inlet -engine block -exhaust risers You get the idea. You can verify engine temps and see if your new 160 degree thermostat is working according to the sending unit and gauge. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: Otto Throttle
Date Posted: July-05-2020 at 11:07am
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Ok Great...I assume that sits right on top above the center fully? Also, can I use a thermostat I pick up from the auto parts store for a Ford 351? It will be nice to change the too so i will know the time on each component! Thanks! Otto ------------- Otto |
Posted By: Jonny Quest
Date Posted: July-05-2020 at 11:38am
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You need a 160 degree thermostat. Auto parts stores may not carry it. ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: 8122pbrainard
Date Posted: July-05-2020 at 12:02pm
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Chris, I wouldn't condemn the T stat just yet. Considering what you just went though with your alternator/battery problem only to find bad connections, I'd suggest checking the circuit for the temp sender and temp gauge too. Get that VOM out again and check the Ohms. Yes, plus 1 on the IR gun. Have you checked the temp with one? Also understand that engine temps will vary depending on how hard the you're running the engine. ------------- /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: Jonny Quest
Date Posted: July-05-2020 at 1:12pm
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Otto: The reason that I recommend a thermostat change is because it is cheap insurance. An over-heated engine can ruin your summer. In an automobile, your cooling system has antifreeze running through the system. The antifreeze has anti-rust agents built-in. On a raw-water cooled marine engine, you have lake water or sea water running through the components. Lake water and sea water contain minerals that can attach to the thermostat. You’ll be surprised at how gunked up the thermostat is when you take it out. I understand Pete’s opinion. You don’t know if the thermostat is faulty, but with a new t-stat you know what you’ve got. A bit more peace-of-mind ... JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: KENO
Date Posted: July-05-2020 at 8:23pm
What he said And I don't know why Jonny is stuck on a 160 degree thermostat if you're gonna replace yours. You could very well have a 143 degree in there, being a raw water cooled, carbureted, PCM 351. The 160 degree ones were in the fuel injected engines. And if you don't have a 143, maybe you should. Once it's open, your temperature will depend on load on the engine, injection temperature and response time to go from one let's say steady state condition to another. If that big hot hunk of metal known as the engine is run hard and you come down to idle, temperature will go up since your cooling water flow has been cut back from around 20 gallons/minute to 5 or so gallons/minute and it has to cool off that hot hunk of metal which will take a little time. You may have nothing wrong at all, but if you check with an IR gun you'll have a good idea whether the gauge is right. Aim it right at the manifold where the temperature sensor is located to compare it to the gauge. There's bound to be a little difference due to heat transfer through the metal of the manifold as compared to the sensor being immersed in the water,sensing the water temperature |
8122pbrainard wrote:Posted By: Otto Throttle
Date Posted: July-06-2020 at 3:27am
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Was running nicely today at 150 degrees...could the improved flow of the new impeller Improve efficiency like this? Going to try and find a temp gun today... Great points being made... my new multi meter will get some use too! I am going to order a spare thermostat as well... being in OH and running in water temps from 60 to 80 what are the pros and cons of the temperature choice ? Before taking off the thermostat housing (mine looks like it has Allen head bolts), should I take off the hoses or can you just loosen the clamps and have enough room to work. Thanks to all that are helping! Otto ------------- Otto |
Posted By: KENO
Date Posted: July-06-2020 at 9:01am
The new impeller can definitely help. It's easier to take the housing off if you take off the hose that goes to the left exhaust manifold, then you can flop the housing over to the right with the other hoses still attached. I think you're looking for a problem that may not exist, but if you're getting a new thermostat get a 143 
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Posted By: Otto Throttle
Date Posted: July-06-2020 at 12:15pm
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Cool! Pun intended! I will just let it ride....seeing that temperature decrease by 20 degrees just caught my attention! I am going to order a 143 thermostat just to have on hand.... Me and Multi meter will do a little probing around later today.... I will post the results! Otto ------------- Otto |
Posted By: 8122pbrainard
Date Posted: July-06-2020 at 12:21pm
Chris, Have you confirmed or know what temp T stat is in there now? If it isn't the 143, then change it to the 143. That's the correct one. ------------- /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: Jonny Quest
Date Posted: July-06-2020 at 2:10pm
Oops. My bad. As the boat is a 1999 I assumed non-carburetor engine. 143 degree is the correct T-stat for carby engines, per PCM documentation. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: flyweed
Date Posted: July-06-2020 at 9:52pm
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I'm running a 143F thermostat on my 93's 351W..and my temps are a pretty constant 125-130F no matter if I am running at idle or WOT. Dan ------------- '93 Ski Nautique NWZ, Air Boom Tower Drink Tonight..for tomorrow We Ride! |
Posted By: Hysteria
Date Posted: July-06-2020 at 10:43pm
| Is there a reason you guys are so keen on the 143 thermostat in fresh water? |
Posted By: flyweed
Date Posted: July-06-2020 at 11:37pm
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take this for what it's worth. From all I have read and have heard from others who have run both the 143 and 160f t-stats is that there is a LOT of starting and stopping with a marine application and when you turn the motor off...cooling is gone. the higher temp thermostat can let the engine head temp get well over 200F. as opposed to a close system with coolant. also, the water flowing around the engine can start boiling, and when it gets that hot it creates vapor or steam pockets, and those pockets dont conduct heat away from the engine, so to reduce that temp, they installed the 143F T-stats to lower the water temp in the engine. The trade off for going from a 160F to a 143F is a bit lower fuel economy. Now...again, this is only what I've been told, so take it at face value. ------------- '93 Ski Nautique NWZ, Air Boom Tower Drink Tonight..for tomorrow We Ride! |
Posted By: Hysteria
Date Posted: July-06-2020 at 11:48pm
| That lines up with what KENO was saying above, but unless your motor is boiling water in the heads I just don't see a strong argument for the lower temp. 200 degrees is nothing to a motor, and wouldn't you be seeing issues with all the fuel injected motors if this were the case? It just seems silly to give up the benefits of a hotter thermostat |
Posted By: Otto Throttle
Date Posted: July-07-2020 at 2:40am
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Interesting as my engine is running around the 140-150 range, so that may be normal for this thermostat set up. I was told 180 is the normal range which is why I was questioning the temperature to begin with. New impeller is better efficiency is lower operating temp...what effect is noticeable when running higher octane fuel...I am running 93? Otto ------------- Otto |
Posted By: KENO
Date Posted: August-13-2020 at 8:56am
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I'm kinda surprised nobody has mentioned that the 143 is a low enough temperature that in salt water it helps to keep stuff from coming out of solution and fouling all your cooling surfaces while at the same time your engine runs cool and runs well. In fresh water..........well it's your choice
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Posted By: Bri892001
Date Posted: August-13-2020 at 10:58am
| A real quick and free check, make sure your water strainer is free of junk, that the o ring is in place, and that it's screwed on snuggly. |