The Stovebolt Site Forums The Shop Area Engine Shop running engine too cool?

Is it possible to run an engine at too low of a temperature? I ask this because I believe I bought a 160 degree thermostat for my 292 before I dropped it in. Now I can drive the truck 30-45 minutes and still touch the radiator without burning my hand. The valve cover isn't very hot either.

Can this affect performance or otherwise harm the engine? Just want to know before I put too many more miles on the new engine.

Thanks!
-ftyler

Is your gauge coming up?

Determine what year the engine is and look up the correct therm. Running too cold the oil will never reach operating temp and increased wear on the bearings / rings etc.

Well, I'm no Chevy expert, but as a general rule the clearances in an engine are designed for when it is hot. When the engine is cold, you get extra wear because there is less expansion and clearance. Somewhere I have an old engine manual that shows a graph for engine wear vs water temp. Wear dramtically decreased as temp increased, and conversely wear increased as temp decreased.

The breakover point was around 160 to 180 degrees. 180 and above had siginificantly less wear. 160 and below had significantly more wear. Thus as a general rule 180 degree thermostats should be the minimum you put in an engine.

It is possible to take operating temperature into account when rebuilding an engine. Most drag race only engines are designed for full clearances around 120 to 160 degrees (or sometimes less). This is because these engines never warm up, particularly those which shut down at the end of the run and are towed back. These engines thus have more clearance when cold. The problem is when they get hot - the clearances can be excessive.

Another problem is the complete removal of the thermostat. Ever seen an engine overheat because the water is too cold? I've seen this several times. The thermostat gets removed, and the water circulates too fast through the engine. The problem is that heat is not properly transferred from the metal to the water. As a result, some cylinders never get enough cooling and they run hot. I saw a 302 **** seize a piston and a 400 Chev gall a piston because of this. If the thermostat is removed it needs to be replaced by a disk with a fixed hole in the middle to slow down the water. (This is why people with cooling problems still scratch their heads when they take the thermostat out completely.)

Unfortunately Tony the temp gauge hasn't worked since the engine swap. I think the new alternator with internal regulator fried the 37 year old gauge.

There's been several great discussions on engine cooling here.Some say the thermostat or restriction provides presurization of the cooling liquid in the block by the pump pushing against the restriction, eliminating steam pockets.Liquid can take on more heat than steam.Some say you should run an engine as hot as practical to increase efficiency ,Nascar engines engines run around 220 degrees for example.Of course, 220 degrees on a street engine is right on the edge, 190 gives a safety factor.

When I bought my 1970 C/10 it had a 160 degree in it. Ran like crap, sucked gas like there was no freaking tomorrow, took 30 minutes to warm up enough to drive, and the heater would not keep the cab warm. I put a 194 thermostat in, and presto-buzango! No more Problem!

Bob
ps,
I just found out yesterday that Patsy Cline is God!

Thermodynamics state that the otto cycle is significantly more efficient if you can raise the temperature differential between the incoming air and the combustion chamber temperature. You can't really lower the temperature of the air much but you can raise the combustion chamber temperature as much as practical. That's why most new cars run 195 degree thermostats. Older cars didn't because of the limits of coolants of the day like alcohol and early glycols. They evaporated at high temperatures.

Best way to check the temp is to warm the engine with the radiator cap loose, then insert a thermometer. I use one that is made for meat, simply wash it off and get it back in the drawer before the wife finds out! I run 180* stat im my 235 year round.

I had a 1986 Calais with 3.0 v6. Ran 195* and never overheated in 7 years.

Here's an important point to consider about engine temperature. That is the fact that the engine must warm up enough to get rid of the blow-by gases produced by normal combustion. This "vaporizing" of the contaminites helps to keep the proper pH of the oil.
In cold winters like we get in Wisconsin, the contaminated oil may get so bad with raw gas that the bearings are actually rinsed of any lubrication. I have changed spun bearings out of several engines where I have first drained out an extra quart of oil. The extra quart was not oil. And the oil was more like dirty gasoline than oil.
I will have to say that engines with carburetors and a bad or poorly adjusted choke are far more likely to have problems than engines with fuel injectors.
Sludge (mixture of water and oil) can also form due to low engine temperature. In the colder climates you may notice sludge as a creamy white to brown color goo in the valve cover or on the dipstick. Either the vehicle is not being run long enough to properly warm up or the cooling system has a problem warming up enough.
Hope I'm not being to long winded!