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Thermostat Temp

Posted by bucky (My Page) on
Fri, Sep 29, 06 at 22:55

I have a G20 Travel Van that blew a rad hose awhile back. While replacing the hoses I thought it would be a good idea to instal a new thermostat. As the van is only used during the warm summer months I installed a 180 degree rather than the 195 that I was replacing. I'm now wondering if this will affect engine performance. It runs fine although much cooler now but will running this cool a thermostat cause performance issues? Just curious. Thanks

Follow-Up Postings:

RE: Thermostat Temp

One of the products of combustion is water vapor, and some water vapor gets past the piston rings and into the motor oil, in the normal course of events. When a vehicle is started up and driven for an hour or more, the oil heats up, and the water evaporates. By installing a 180 degree thermostat, you have caused the engine to run cooler, and this will result in more water accumulating in your oil, if you do mainly short trips. If you ordinarily drive the vehicle for an hour or more, per trip, then there will be time for the water to evaporate, so there will be no problem.

RE: Thermostat Temp

**It runs fine although much cooler now but will running this cool a thermostat cause performance issues?**

Nope. That's plenty warm enough for the engine management system to go into closed loop. The thing to remember about thermostats is they only set a minimum temperature. They do nothing to restrict how high the temperature can go. Whether its a 160* or a 195*, once it's fully open, that's all it can do. The maximum temp is to the rest of the cooling system. In other words, if your engine had a funtioning 195* thermostat and the engine temp always goes to 230*+, putting in a 180* or 160* stat wouldn't prevent that from happening. Might take it a little longer to get there, but it won't stop it. You'd have other issues. If you put in a 180* stat and it's holding at 180* on a warm day, you've got a pretty darn good cooling system. There is no advantage to going from a 195* if that was stock to a 180* stat. Does no harm either. jmo

RE: Thermostat Temp

One thing you have to ask yourself. Why would General Motors spend millions of dollars testing engines and then deciding to use a 195 degree thermostat rather than 180 degree thermostat. Do you figure they had a reason to do so? If your vehicle is a computer controlled engine the reason may be so it can get hot enough to go into closed loop. And let the computer control the fuel management system. I have seen units where the thermostat is stuck open just a little. And it would take for ever to go into closed loop. And after being in closed loop for a short period of time it would fall back into open loop because it was running too cool. Just food for thought.

RE: Thermostat Temp

Raising the coolant temperature from 180 F to 195 F reduces emissios and inceases engine efficiency. However, I suspect that lubricity is better at 180 F with longer engine life. There is an argument that engine life may not be extended since the higher temperature tends to keep more moisture and condensates out of the oil.

The engine may not pass emissions tests when the coolant is too low.

Regarding the oxygen sensor, most systems go into "closed loop" operation around coolant temp of 140 F, therefore, the oxygen sensor function should be operable at 180 F. Some systems may set a trouble code for "temperature too low". Some emission test stations scans the engine controller for certain trouble codes.

RE: Thermostat Temp

This is a good info. I didn't know higher engine temp improves efficiency. I recently had my thermostat changed, and the first thing I noticed was the engine seems to heat-up much quicker (judging from the temp guage on the dash). I'm not sure what size thermostat he installed.


RE: Thermostat Temp

Thanks a lot for the response to my question fellas. A few varying opinions and good information that have improved my knowledge and changed my thoughts on running a much cooler thermo. Think I'll reinstall the 195 in the spring.
Cheers: Bucky

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