Thermostat Troubles....every year
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URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=38907
Printed Date: December-02-2024 at 10:19am
Topic: Thermostat Troubles....every year
Posted By: *mtrbtr*
Subject: Thermostat Troubles....every year
Date Posted: June-05-2016 at 11:30pm
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So every spring I have owned this (97 sport GT 40) boat the thermostat seems to give me problems. I always just replaced it since it was cheap and things worked fine the rest of the year. This spring I thought I would just beat the problem to the punch and put a new one in as a normal part of maintenance. I had a few other issues out the gate this year but running it with the bucket in the yard and at the lake last week the temperature wasn't one of them. Today I all of the sudden have temp problems. So I pull the thermostat and everything cools right down when I run it without the thermostat. Put it back in and things heat up. This was a brand new thermostat. I am beginning to wonder if I have a different issue don't have a weak raw water pump or something. I did not replace the impeller this year but I did pull it out of the pump last fall and put it in a bag. Is there any reason why water would have trouble going through the thermostat? I'm going to put a new impeller and yet another thermostat in just for good measure and see what happens but hoping someone has some ideas. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Replies:
Posted By: Gary S
Date Posted: June-06-2016 at 1:14am
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Are you using a genuine PCM 160 degree thermostat? ------------- 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: *mtrbtr*
Date Posted: June-06-2016 at 8:18am
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I have tried both pcm brand from nautique parts and one from the local parts store and both seem to give me trouble. I just ordered another one from NP. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: LeftFieldEngineering
Date Posted: June-06-2016 at 8:24am
| When does it heat up? At idle? At speed? |
Posted By: *mtrbtr*
Date Posted: June-06-2016 at 9:18am
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At speed ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: 8122pbrainard
Date Posted: June-06-2016 at 9:21am
What temp does it get up to? ------------- /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 < |
*mtrbtr* wrote:Posted By: SNobsessed
Date Posted: June-06-2016 at 10:25am
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You might want to test the 'stat in a pan of water on the stove top. Use a thermometer to see what temp it opens up at. My buddy has an I/O on which has same problem. He took it to a mech who replaced outdrive impeller (which didn't help) & then told my buddy he didn't want to work on it any further (is why I got involved). I searched online & saw that blocked exhaust manifolds/ risers is a common cause for high speed overheat. I took off 1 riser & it was like new, so no cigar there. We back flushed thru the hose leading to riser & that did reduce the problem considerably, so that points to sand buildup in system somewhere. Good luck. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: *mtrbtr*
Date Posted: June-06-2016 at 11:00am
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I never let it get up above 190. When I took the t stat out it would run around 120 at speed. Pretty sure my hoses are fine since I have had them apart so many times this year. Also the water we run in is cleaner than most lakes. But just in case can you explain the process of backflushing? ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: LeftFieldEngineering
Date Posted: June-06-2016 at 11:12am
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I had a weird overheat issue with my 79 tique 351. It would be cool as a cucumber up to 35 mph then heat up at barefoot speed. I thought it was a pickup problem because it was cool the rest of the time. Turned out to be a bad mechanical seal in the raw water pump. It would leak air which would collect at the top of the intake manifold causing high temp reading. I used an infrared thermometer to keep an eye on different parts of the motor. A Major RWP rebuild kit fixed it, now it runs cool up to 50 mph. |
Posted By: *mtrbtr*
Date Posted: June-06-2016 at 11:13am
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I've tested every one on the stove. They all seem like they work properly. Its just weird. Usually a new one does the trick. Maybe the one I got this year was just cheap. Could a weak impeller or raw water pump not force it through the T state well enough? That's the only thing I can think of that could be wrong since it cools right down without a t stat in at all. I plan to put a new impeller in next weekend along with a PCM impeller but it just doesn't seem like I should have this much trouble with t stats. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: *mtrbtr*
Date Posted: June-06-2016 at 11:16am
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It doesn't heat up at speed without the thermostat in. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: Hollywood
Date Posted: June-06-2016 at 11:26am
| I would be testing the RWP performance |
Posted By: bb12
Date Posted: June-06-2016 at 11:37am
x2 What he said |
Posted By: LeftFieldEngineering
Date Posted: June-06-2016 at 2:26pm
Have you confirmed it's actually getting that hot or just the gauge? When I had the air pocket problem from the leaking RWP the gauge would read off the chart yet I could still keep my hand on the water pump u bend or the intake manifold. When you remove the t-Stat it allows more of the air / water thru which is seen as a drop in temp. Like the others said: test the RWP. |
Posted By: tryathlete
Date Posted: June-06-2016 at 2:57pm
| Not thread jacking hopefully--can I replace the T-stat without removing the hoses from the housing on my GT-40? Is there enough slack to lift the housing still attached to the hoses? Mine are stuck on and i just want to get the stat in since mine is stuck open. |
Posted By: Hollywood
Date Posted: June-06-2016 at 3:02pm
| Yes? If not remove just the starboard side exhaust feed. |
Posted By: *mtrbtr*
Date Posted: June-06-2016 at 3:20pm
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Tryathlete: I was able to get mine out without removing the hoses. I don't think the gauge or the sender on mine is wrong since the water was hot when I pulled out the thermostat plus I replaced the sending unit on mine last year before I figured out I had a bad thermostat at that time. I am going to go ahead and order a new water pump. Pricey but I am a little suspect of it anyway and it has been making some noise lately. Will get the new stat and pump on with new impeller and see what happens. Might be overkill but I have some church camps I am committed to in early July and don't have a lot of time to be messing with things, ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: tryathlete
Date Posted: June-06-2016 at 10:09pm
I think LF is onto something. What bothers me Is that the replacement solves the problem each year. Are you running in brackish water? Do you winterize with marine coolant? I replaced mine (ran 120F like yours--was stuck open) and now it runs 160F all the time. |
Posted By: tryathlete
Date Posted: June-06-2016 at 10:19pm
| Hollywood--one side removal. This was key! Starboard side came off easily. |
Posted By: tryathlete
Date Posted: June-06-2016 at 10:22pm
Not sure where you're buying it but I did see on eBay someone selling "rebuilt" pumps for much less than new although I would call and inquire what the "rebuild" includes. http://m.ebay.com/itm/141665585767" rel="nofollow - Ebay water pump |
Posted By: *mtrbtr*
Date Posted: June-07-2016 at 1:13am
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Not in brackish water. (Montana). I did see the rebuild on eBay. I Winterize by draining the engine. then sucking marine coolant through and then draining it again. Not sure if the coolant could be causing problems but again put a new stat in as part of the dewinterizing process. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: tryathlete
Date Posted: June-07-2016 at 1:30am
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My TS was 20 years old I suspect. It failed due to corrosion. Automotive TS last forever in most cases because they are protected in coolant with anti-corrosion additives, and our thermostats sit in air or water. I know my thermostat was dry and not soaked in coolant over the last 20 winters. I dont know anyone who has the troubles you're having who operates in fresh water. I'm really curious about what is happening with yours. |
Posted By: *mtrbtr*
Date Posted: June-07-2016 at 10:47am
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Me too! I wonder if maybe it's getting hung up on the housing some how. Going to look at that. i know that they have changed the design of the Ford Thermostats in the last few years and you can't hardly find one like the original. Even the oem ones from PCM have a different design. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: SNobsessed
Date Posted: June-07-2016 at 10:54am
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Any chance it is getting 'pinched' during installation? I did that once (in a car) & it would open erratically. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: gun-driver
Date Posted: June-07-2016 at 12:21pm
Cut and paste from ad, PRODUCT DESCRIPTION: OEM Sherwood G20 / G21 Raw Water Sea Pump. Disassembled / Media Blasted / Inspected / New Parts Installed / Painted / Tested. New bearings, SS bolts, impeller, o-ring, gasket, mechanical seal and retaining rings are installed. Grooved wear plates are resurfaced or replaced. The pumps are painted Black and the body is left brass. They are tested and lubricated with glycerin impeller lube. |
Posted By: tryathlete
Date Posted: June-07-2016 at 2:05pm
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That is a pretty thorough description-- would probably buy a new one anyways simply because it is not THAT huge of a savings versus something like a transmission where new versus rebuilt is so substantial. I should look into making them myself at our factory in Shanghai. Would be a high margin item for sure if there were enough sales to justify it. I think I will call PCM and see how many they need in a given year. |
Posted By: *mtrbtr*
Date Posted: June-11-2016 at 5:19pm
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So I took the boat out today with the new raw water pump PCM Thermostat. Seemed to run fine for a while then it heated up suddenly again. I pulled it and it cooled right down. Put it back in and it ran fine for a while right at temperature and then suddenly heated up again. I don't understand why it runs fine without it. I took it home and tested it in water. It opens very wide at 190 and about 1/4" at 170 and not at all at 160. Maybe I have bigger issues like a cracked head but I am at a total loss right now. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: tryathlete
Date Posted: June-11-2016 at 5:36pm
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I wonder if your engine circulation pump is not functioning properly. The raw water pump cools th manifolds and feeds water to the engine block but the other one...,just a guess. Others far wiser and with decades of this stuff should follow with more ideas. Is there a hose that may be collapsing from the suction on the hose from RWP a possibility? Is any air leaking into the cooling lines from a loose hose fitting of maybe the gasket on the raw water filter? |
Posted By: *mtrbtr*
Date Posted: June-11-2016 at 6:12pm
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I did pull one of the plugs and started the engine and revved it and water sprayed out. According to Skidim that is supposed to be how to test if the circulation pump is working or not. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: Gary S
Date Posted: June-11-2016 at 6:23pm
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The circulation pump on my Florida boat started started to make alot of noise.I pulled it to replace and found a regular automotive pump was installed by a PO. The vanes on the pump were almost rusted away,it never overheated nor run hot. So I don't know if it would be that. ------------- 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: *mtrbtr*
Date Posted: June-11-2016 at 10:32pm
So I read about the old style thermostat and the new style. Nautique Parts and Ski dim sell a thermostat that looks like this. From what I understand the original thermostats which you can still get at NAPA look like this.  The first one I ever took out of the boat looked like this too. NP assured me that the new style was an upgrade and would work fine. (It did for a season) Went down to NAPA and got one. Drove the one hour back to the lake and it seemed to work perfectly. I ran the boat pretty hard for quite a while at different RMPs and the temperature was pretty stable. It ran a touch warmer on my gauge than the other ones did when they were working but I could watch it fluctuate on the gauge about 5 degrees when it opened and closed. To me the way the old style flows water through makes more sense. Somewhere on another thread I remember them talking about these different styles of thermostat. So after 2 trips to the lake today (180 miles) I think I solved the problem. Hopefully it wont show back up next weekend. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: Gary S
Date Posted: June-12-2016 at 1:00am
This is the style PCM has used for quite awhile,I still have the one out of my Dads 87 and one out of a late 90's GT40.  Found http://www.jegs.com/p/Milodon/Milodon-High-Flow-Thermostats/762929/10002/-1" rel="nofollow - this too, interesting reading. I would guess our systems are considered high flow I would think. ------------- 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: Hollywood
Date Posted: June-13-2016 at 11:25am
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I don't agree with your original thermostat assessment. I have not pulled any of those out of PCM Fords. The PCM 454 has the bulky pass-through thermostat that sucks. It'd over $100 and does a ***************ty job of maintaining operating temperature. Their "fix" is a higher rated thermostat. Well that just doesn't seem right to me. Instead, we put a MerCruiser housing on the 454 and now use the normal looking, inexpensive 143 also commonly used in the Fords. Engine now runs right up to 160 and stays there, where before it would struggle to get to 120 idling, then climb to 170 and fall off immediately again with any amount of throttle. The Ford PCM housing Gary showed has a natural pass through you don't need any funky thermostat. |
Posted By: KENO
Date Posted: June-13-2016 at 11:54am
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mtrbtr Like Hollywood said, that"new style" as you call it has been in PCM 351's since PCM has been around. That's back in the 70's. |
Posted By: *mtrbtr*
Date Posted: June-13-2016 at 2:49pm
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I could be wrong on the old style new style. I just read it on this forum somewhere a while back. Could be bad information. I can just say that I have had 4 high flow thermostats in the boat. So far 2 of them this year. The boat runs very cool with no thermostat in it and I believe the circulation pump is working based on the test shown on the Ski dim site. The NAPA $8 thermostat is working for me. Wish I knew why. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: tryathlete
Date Posted: June-13-2016 at 2:57pm
| I just replaced my stuck stat with a NP stat and it keeps my GT-40 at 160+\-5F. Only warms up if I let it heat soak by turning it off. Unlike pass car no electric fan for the radiator to cool it when stopping after a hard run, but it still only hits 200F for a few minutes. I'm very happy with the 160F thermostat. The old one, stuck upon was like yours without a stat--120F. Never had any running problems or fouling of plugs (probably because it gets run hard often enough on an occasional blast around our small lake). |
Posted By: bb12
Date Posted: June-17-2016 at 3:15pm
| Johnathan, did you ever get your temp issue figured out? |
Posted By: *mtrbtr*
Date Posted: June-17-2016 at 5:23pm
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Haven't had a chance to get back out, weather and other projects have prevented me from doing too much, but the NAPA one seems to be working currently. I called Nautique Parts and told them about my problems to see if they had any advice and they offered to send me a new PCM thermostat so I might try that one again. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Posted By: SNobsessed
Date Posted: June-17-2016 at 6:26pm
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It would be interesting to boil both of them side by side & see which one opens 1st & by how much. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |