Solved thermostat problem on Universal 5432

[bwindrope]

For anyone else out there with a diesel that runs too cool, especially a Universal 5432, I am happy to report that I have solved this sort of problem on Aeolus. In short, the factory thermostat is rated 160, which as many will know is fine if you are raw water cooled to prevent salt crystals forming, but for those many of us with fresh water cooling, 160 is way too cool. This can dramatically shorten engine life and produces carbon build up in the usual places.

The engine manual says the optimum temperature is 170-185 and yet Universal only provides a 160 thermostat. Go figure. Without giving a dissertation on the things that influence engine temperature, suffice to say here that Aeolus ran a steady 160 no matter how hard she was run, and that this was controlled entirely by the 160 thermostat setting in my case. She has an extremely efficient cooling system.

After a lengthy search involving all the usual steps, I found my answer. Car Quest makes a 180 and 195 degree thermostat that is an exact match. They are actually made by Stant and just rebranded by Car Quest. I put the 195 degree in Aeolus tonight and ran her up to temperature and she parked herself on 190!!! Perfect.

Car Quest part number 31979

I could just see the carbon burning off the piston rings and the valves. In my case this is especially important because I run a high % biodiesel for all the mechanical and environmental benefits, and it has a slightly higher flash point which is helped by the higher operating temperature.

As only someone who really knows their boat can appreciate, I noticed a distinctly quieter and smoother sound to her tonight while running at the higher 190 temperature.

For pictures and more of the story see my boat blog at Stories of Aeolus- Our Gulf 32 Pilothouse

I hope this helps anyone else out there who has an efficient cooling system and who worries about carbon build up with an engine that is running too cool.

[JohnRPollard]

Hey, that is great info. Very nice of you to share it.

One question: If the manual states optimal operating temp is 170-185, why did you decide to go with the 190 thermostat when a 180 was available?

Okay, one more: Do you have the part no. for the 180 thermostat available?

[bwindrope]

Hi John,
I'm glad you think this information is helpful and I truly hope it is. The only reason I post and do a blog is because I myself have spent so much time trying to learn from other people and feel I should do my part.

I am using the 195 degree for now because even with that she runs a steady 190 degrees. From all I can read this is well within the safe margin for continuous operation and I am hoping to burn off any accumulated carbon that might be removable. As long as she stays around 190, I see no reason to change. Again, between our 45 degree water and my efficient cooling system, there is virtually no cause for concern about overheating as she never budged above 160 before.

I suspect that with the 180 degree thermostat that she would run between 175 and 180, which is at the lower limit of fine, but after her being run 700+ hours too low in temperature, I am anxious to run her at the upper margin of things.

The CarQuest part # for the 180 thermostat is: 31978

Hope this helps.

[fuji0030]

I doubtable that with the 180 amount thermostat that she would run amid 175 and 180, which is at the lower absolute of fine, but afterwards her getting run 700+ hours too low in temperature, I am afraid to run her at the high allowance of things.

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Thermostat

[MHRitter]

I found a 180 deg thermostat NAPA 143 with no holes. Sure gets warm a lot faster than the 160 deg thermostat with the two holes.

[timebandit]

The hole(s) are there to allow air to escape when filling the cooling system.

Without the holes the engine could overheat because the traped air under the thermostat will not heat the element enuff for it to open untill the engine is over heated and then if it does open it will allow cold water to hit the hot engine parts, not so good.

I imagine a sea water cooled engine would have this problem every time it is started.

If you don't have a hole in your thermostat I think you should drill a small pin hole in it.

[johnhumid]

the factory thermostat is rated 160 and it is way too cool, but i guess it is not favor to the engine, that might slowly produce carbon build up on some places...