Running hot....maybe? Help for LT1

[Red95bird]

My friend has a 93 Hawk. He had a problem of having the engine run hotter than normal. He heard of changing the thermo would solve the problem, as well as more coolant ( it was little low ). We changed the thermo with a 195. We added more coolant. We took it for a spin after and the engine rose a little past 220. After the shprt drive we took it back and didn't see any leaking of any sort. The oil is around 50, but jumps when revving or accelerating. Is this normal or is there something wrong?

[Jeff_in_Atl]

Did you bleed the system. It will overheat if you don't. http://shbox.com/1/bleeders.jpg

[Mirroredshades]

I read somewhere that this is the normal operating range. GM set the coolant fans to come on at 225. Mine runs just as you described. This personally makes me very nervous. You can get an SLP 165 Thermo and a fan switch that turns the electric fans on a lot sooner. I think like 195.

You should also bleed the system as the above post states.

[Kevin - Blown 95 TA]

Make sure the air dam is in good shape or get a new one. Also, you could try adding some Water Wetter, although it isn't as effective with 50/50 coolant mixtures. You could always do a coolant system flush.

[Injuneer]

Why would you put a higher than stock temperature thermostat in an engine to cure an overheating problem? The stock t'stat is 180degF. Most people opt for a 160degF 'stat, and program the fans to keep the temps under 190degF. In any case, the t'stat simply determines at what temperature the coolant starts to circulate through the engine. It can not do anything to control excessive temperatures.

The stock system will typically run about 190-195degF at high speeds on the freeway, and bump up to 210-220degF in heavy stop-n-go traffic in hot weather. The stock programming turns the first fan on at 226degF and the second fan at 235degF. As you can see, the factory prefers the higher operating temperatures, for low emissions and high fuel milage.

If the car suddenly starts running hotter than in the past, and its an 11 year old car, could be any number of ailments in the cooling system.... plugged radiator core, dirt and debris in front of the radiator, collapsing coolant hose on the suction side of the pump, failing water pump, stuck t'stat, air in system, etc.

[Red95bird]

[QUOTE=Injuneer]Why would you put a higher than stock temperature thermostat in an engine to cure an overheating problem? The stock t'stat is 180degF. QUOTE]


I thought the stock stat was at 180 also. He said his gauages aren't precise and have been crazy for awhile. He said normal running periods (city) he is just below 220. He got the "heavy duty" stat, he was told to get this at Checkers. He couldn't find another place around that sold stats so he went with this one.

[Injuneer]

Is the thermostat specifically made for an reverse cooled LT1? You can not use a "standard" t'stat with the LT1. It needs a special t'stat that responds to the reverse flow cooling. Typically these cost $15-20, compared to the normal $5. If you had the wrong one, it can cause some bypassing of coolant. Most auto parts shops are not familiar with this.

This picture is from Shoebox's Tech Pages. He has a complete radiator/coolant service procedure there:

http://shbox.com/1/4th_gen_tech2.html#thermostat_change

[Red95bird]

I'm taking it that this guy was not aware if this. We purchased the closed one without the reverse flow for about $9.50. Also how do you properly bleed your system?

[Jeff_in_Atl]

Read this.
http://shbox.com/1/4th_gen_tech2.html#thermostat_change

[Red95bird]

Thanks guys