View Full Version : Proper thermostat

02-04-2012, 05:20 PM
We took the thermostat out today to replace it as part of the rebuild and noticed that it was stamped for 140, now the manual says 160. Which is correct?

We put it in a pot of water and it opened up around 150.

02-06-2012, 10:27 AM
Anyone? Engine is 5.7 TBI

02-06-2012, 11:05 AM
The only problem with a cooler thermostat than book statement is that it will sometimes affect the ecm. Warm engines run richer most times. Hot engines run lean. Too hot engines don't run for long. The proper thermostat should not hurt your engine. Buy a good thermostat rated for marine use. I actually don't know or care if all thermostats will work in marine use because I buy from SkiDim and expect the experts to get it right. With that said, here is what I have done all of my life. I always run a thermostat in everything I own that is cooler than book recommendation. I like rich, cooler engines. Truck, jeep, airboats, and my Mastercraft all have thermostats at least twenty degrees cooler than book recommendation. I even go further and drill two to four smaller holes in the inner ring that is clear of the gasket so that if any thermostat sticks closed I have water flow. This affects warm up time but I have never lost an engine since I started this practice 38 years ago. The bad thing about my practices is that it was trial and error plus I am environmentally uncaring when it comes to my exhaust emissions. I like my engines rich and warm instead of lean and hot.

02-06-2012, 11:06 AM
Anyone? Engine is 5.7 TBI

Call Chuck @ BAWS 813-996-2297

02-06-2012, 11:07 AM
Hope that helped but someone else may have a better answer.

02-06-2012, 11:15 AM
It depends on the boat engine. My 94' LT1 engine has 2 t-stats. One is a 142 and the other is a 160 degree one.

I'd stick with the manual if it says 160. 140 seems low if you only have the one. Mine has a "pre" t-stat and then onto the main 160 stat. If the engine is around 140 all the time, it may not really be in it's ideal operating temperature.....

And your heater probably isn't too hot either. :(