'89 351 Indmar constantly 140 degrees

[homer12]

My engine in '89 Tristar never gets much past 140 to 145 deg after running constantly at about 2500 rpm's. Does that seem normal for this engine? I thought I should be running closer to 160 constantly? If that seems cold, I'm guessing start by checking gauge, then sensor, then thermostats, right...

[slushpup]

Dumb question but, a 351 will run arond 140 with no T-stat,Are you sure it's in there? I Forgot one season To replace mine, Boat ran cool and annoyed me till found it in the glove box.

[Spork]

That's a true statement an open or missing thermostat will operate a 351w at 140 degrees.
First I would check the thermostat, that's the easiest and cheapest item.

[Engine Nut]

My engine in '89 Tristar never gets much past 140 to 145 deg after running constantly at about 2500 rpm's. Does that seem normal for this engine? I thought I should be running closer to 160 constantly? If that seems cold, I'm guessing start by checking gauge, then sensor, then thermostats, right...

The 351 has a 140 thermostat. If you are running at 140-145 you are right where you belong.

[Dino Don]

Mine ran that way until I replaced it and now it's at 160. Engines can run too cool as well as too hot.

[homer12]

Well, I've never touched the thermostat so probably time to check. This would be the one on top of the water pump right? Is it a 143 or 160 t-stat to be sure?

[Spork]

Well, I've never touched the thermostat so probably time to check. This would be the one on top of the water pump right? Is it a 143 or 160 t-stat to be sure?

^ according to engine nut it should have a 140° thermostat. I ran my 351w without a t-stat for a summer (mistake unknown to me when I bought my boat) and it ran at 140. I installed a 160° thermostat from http://www.bakesonline.com/detail.aspx?ID=844 and it operates right at 160-165 on my gauges.

[homer12]

Then any harm in running 140deg? I don't understand what damage or harm could be done by running a cooler engine. Looks like according to Bakes it may just be more efficient around 160deg

[Spork]

Then any harm in running 140deg? I don't understand what damage or harm could be done by running a cooler engine. Looks like according to Bakes it may just be more efficient around 160deg

Imo no problem, only issue I could see is if a heater is in play it probably won't work properly with a damaged or missing thermostat.

[Spork]

Well, I've never touched the thermostat so probably time to check. This would be the one on top of the water pump right? Is it a 143 or 160 t-stat to be sure?

Location of thermostat...

[homer12]

Thanks, mccreight! That's super easy to check. Would you recommend I have a gasket if I'm going to pull the top off and check it?

[thatsmrmastercraft]

The existing gasket never survives to be used again. The gasket is cheap, so get one with the new stat, and apply a little silicone to both sides of the gasket to keep it in place and prevent any leaks. And don't over-tighten the housing.