I was having trouble packing the radiator on my 87, so I used the alternate method of drilling 2 holes in the stat body and it packed on the first try, no more low coolant light. The problem is I have a 180 stat with my fan set at on @200 and off @185 but this morning the temp never got over 150 on the way to work with a 30 degree outside temp. It was in the 175-185 range on the way home with a 70 degree outside temp but took 10 min to reach that temp. Is this too cool for a aluminum head motor as a new stat is an easy swap. Before the holes it was steady at 175-185 driving and never over 205 idling.

 

My opinion:
Yes not getting over 150 is way too cool.
Even 175-185 is on the cool side.

You want it to be in the 190-195 range.

 

IMO You don't have to drill the thermostat in an 87. Raise the nose when you fill the system.

 

You can't raise the nose on an 87 high enough to get rid of air in the cooling system!!!!! The way to get rid of air is to start cold, open rad cap to its first detent, start the engine, when the coolant gets to the opening temp, raise the engine rpm by pulling on the cable end stop on the front of the MAF, remove the rad cap, you should have seen the coolant drop out of sight. Fill the rad to the neck, install the rad cap and let the engine rpm back down to idle.

 

Sounds like you drilled holes to big and now to much unheated coolant is getting by the thermostat, either that or you stat is bad.. Your only suppose to drill either one 1/8 inch hole or two 1/16 inch holes.. Any more than this and the coolant takes forever to get to temperture..WW

 

It isn't necessary to drill holes in thermostats. I have been driving my 87 vette every day for 21 years now. The factory thermostat is 195 F and is what I have been running all 21 years. Normal coolant temp is close to 195 when you are underway. At stop lights no air is passing through the radiator and the coolant temp rises. At 228 F the main fan comes on and the coolant temp will drop and the fan will turn off at 210 F and the cycle will start over. If the coolant temp gets to 238 F, the aux fan will come on. Even 238 F will not harm anything in the engine and is no cause for alarm. GM says if the coolant temp gets to 260 F, to turn the engine off and let the engine cool down. Why we have so many people that want their C4 to run at lower than what the factory designed their cooling systems is beyond me. C4's pull air in the bottom of the car and the radiator gets debris jammed into it and cooling decreases. Periodically you should clean the radiator out!
You can do real harm running the engine at too low a temperature. Low temps will not remove condensed water in the engine oil and sludge will form and cause serous engine wear. Cooler engines generate less horsepower and get poorer fuel mileage.

 

I only have 1 fan and it's set in at on @ 200 and off @ 185. If I go with a warmer stat my fan could end up running all the time. It's a high mileage motor (204k) that's probably getting rebuilt next season but doesn't use any oil and still runs good.

 

And why did you change the fan temp programming?

 

i just drilled the 2 1/8 inch holes in my new 180 degree thermostat and my coolant will not reach temperature while I am driving.

I have to go buy a 1/8 inch drill bit (the other one snapped and gouged my hand as i finished the second hole) and a new 180 degree thermostat and gasket and go install it.

I will only do one 1/8 hole this time for sure. I made a mistake the last time and it is a complete PITA.

Mike

 

Like JFB mentioned above, you really don't have to drill holes in your stat to get your cooling system full, it just makes it easier by allowing the coolant to purge through the holes thereby removing air and equalizing the system . I prefer to (Pack) the cooling system the old fashion way ...WW

 

An engine that is too cold will make less horsepower. But a motor at 170 degrees will make more than one at 220.

 

Not true. Internal combustion engines work on heat. You steal heat from the combustion chamber, you are stealing horsepower. Even Smokey Yunick said in his last book that NASCAR racers run 240-260 F to obtain maximum horsepower. My brother has an engine book with a section written by Continental. They took some small liquid cooled engines (25 HP) and ran them at fixed temperatures ( 160 F to 240 F) and measured the HP , specific fuel consumption, and cylinder bore dimension change. Horsepower increased with increasing temperature. Fuel consumption decreased with increasing temperature. Cylinder bore diameter decreased with increasing temperature.

 

Being that the factory stat was a 195, I didn't think that a 180 stat would be a problem. It seemed that 200 degree fan on and 185 degree fan off would keep the fan from running too much and maintain the engine close to the stat setting. It seemed to make sense to maintain a constant temp rather than to not turn the fan on until 30 degrees over the stat rating. I was going to replace the 180 stat with a new one, but reprogramming the chip and a hotter stat isn't a big issue if it's going to cause that much of a problem. Thanks for everyones input.

 

The factory radiator is not large enough to maintain 180 F in warm weather, so your 180 F thermostat is going to be wide open all the time and you will still have about the same coolant temp, 195 F, as the cooling system was designed for and your fan is going to be on all the time. Your efforts will do nothing to keep the engine temp more constant. If constant temp were so important, the GM engineers would have designed the cooling system to do that.

 

I am forever amazed at how cool my '85 runs. In fact, at low ambient temps it runs so low the DN OD has trouble keeping engaged. I am considering putting in a higher temp stat cause it stays between 160-180 but living in the South where the temp hits triple digits I am hesitant to do anything. I always thought a gas engine running cool was a good thing and I read here its not. Its great the Forum gives so much info but in the end, its what view you wanna believe.

 

Late model fuel injected motors will pull timing as the temperature increases to decrease knock. There is a huge difference on my C6Z06 on the dyno when the motor is at 170 degrees vs 210. Some forum members have shown as much as 40 hp difference on the dyno depending on water temperature.