[85vette]

Originally Posted by Rich Z

I read somewhere that some people claim this will actually make the engine run hotter. The argument being that the coolant rushes through the engine too quickly to allow heat to transfer to the coolant, and in the same vein, the coolant moves too quickly through the radiator to allow the coolant to shed the heat into the coils and fins of the radiator.

That being said, I am not sure I believe it. I would think the coolant would have to be moving awful damned fast for this to happen. And it seems to me that if I am overheated from working outside and jump into a cold shower, the faster the water flow the better to cool me down.

But bear in mind, that this is a cooling SYSTEM. The thermostat is only one part of that system. It is designed to regulate the amount of coolant that can pass through the engine based on the temperature of the coolant. If your entire system will not allow the coolant to drop down below 195 degrees, then a 160 thermostat isn't going to do much beyond opening sooner then your engine goes from cold to hot. Once it reaches full operating temperature and the coolant never drops down below 195, because it CAN'T, then the thermostat is completely out of the picture until you shut down the engine and the coolant cools down enough for it to close.

Now, if you add a hi-cap radiator and/or make other modifications whereby the operating temperature is more like 180 degrees, then replacing the stock thermostat with a 160 WILL drop the temp of the coolant during regular operation. Whereas if you had done those same mods with something like a 200 degree thermostat, then the thermostat just would not allow the coolant to drop below it's opening temperature. Because if the temps DID drop below it's opening temperature, it would begin to close, restricting the flow of coolant, and cause the temps to RISE. Not sure how good this would be for a thermostat to be constantly cycling opened and closed, but I would imagine that premature failure of the thermostat may be in your future that way.

Now, with no thermostat at all, I guess you would be able to see what the running temperature of your engine stabilizes at, and perhaps use that as a guide as to whether just adding a lower thermostat will be worthwhile for you or not.

In my opinion, of course.

Yes, they will run hotter with a lower temp thermostat. I had a 1978 Plymouth Trail Duster (anyone remember them?). I was going from Florida to California when my thermostat stuck on me in Texas. I went to a parts house and bought a 160 degree thermostat (that's what we all did back then) even though it came with a 195. I thought that was rediculously high! I left, the temp was running 160-170. Thirty miles down the road at 70 mph on I-10 (yes, the speed limit was 55) it starts rising gradually until it's up to 240. I had to pull over and run water on the radiator until it cooled down. I made it to California repeating this manuver. It never had a problem in the cities or when I was off-roading in Hollister Hills, only when I was traveling on the highway. It took me almost a year to figure out that the water was moving faster than it could cool. I changed back to a 195 and never had another problem with it on the highways or off-road.

The moral of the story: The automakers pay their engineers a lot of money. They generally do things for a reason. The cars in the late 70's were made to run hotter to meet emissions standards. I realize now that altering the thermostat value would require expanding the cooling system capacity in order to achieve a cooler running engine, but few of us gave that much thought back then. We just couldn't figure out why the engineers would be so stupid as to want the engine running at 195 to begin with.....college educated morons.....