I recently purchased a 1990 IROC Z-28 5.0l convertible from a friend. When I purchased it, he mentioned the fact that in the summer, it would run hot but would not overheat. Well...a week after I purchased it, I was shocked to look down and see the temp needle in the red area, almost at 260 degrees. Prior to that, it was hovering pretty much around 220. Well, after sweating bullets all the way back to my home, I looked over the cooling area but did not see and readily apparent leaks. After contacting my buddy, he said that 235-240 was not unusual for a hot summer day, and that he had had the car in the GM shop at least 3 times when he first purchased the car, for the same issue...i.e. high coolant temps. Each time, GM assured him that the car was fine, and the TPI with the aluminum parts was the source of the higher temps above the 195 degrees Mr. Haynes seems to think is normal. Well....he had already replaced the radiator....I have 2 fans (1 comes on w/AC, one w/temp) that both work, no apparent blocks in front of the radiator, a 160 degree t-stat (he put that in), and I just purchased and installed a JET fan switch which kicks on one fan at 195 degrees. Even with this, this afternoon in Va. Bch...with the outside temps about 95++, my temp gage read 220 (more or less....usually was a bit beyond 220). When I called a local Chevy dealer and asked about the temp issue, I was told that, basically, as long as there isn't steam coming from the radiator, and that when the temps outside are cooler the car temp runs cooler...then all was ok with my car.
So, guess the question is...for a 5.0l TPI engine in a IROC Z car, are there folks out there who run cooler than 220 on hot summer days?? Should I continue to investigate this issue, or just accept that the TPI engine will run hot, that is that? I have picked up on some other options....like wiring both fans to come on when I want them to...also, drilling holes in the t-stat (though don't know how big the holes should be)....and the point about too much coolant was interesting, I may have added too much when I replaced the fan switch....probably more like 70/30 coolant to water in my car.
Anyway, all advice is appreciated!! Thanks!

TronGod

 

Your engine is operating normally but, to help it run even cooler, I would change the thermostat to a 180* and drill two 1/8th inch holes on the edges because it helps purge the cooling system of air that gets trapped in the cooling passages. Next I would replace the stock water pump with a high quality "Stewart Stage 1" pump and finally replace both fans with two "Perma Cool" 14" high cfm low amp fans. These parts are inexpensive but are of very HIGH Quality and are very easy to install. Also, just use 1 gallon of coolant which should make the ratio close to 70/30.

 

Thanks GKK....anyplace in particular that I can get those parts from, or does Advance and Pep boys carry stuff like that? To be honest, I am going to watch the temp for a couple of days of driving, then decide what to do next....water pump will probably be one of last things as that is the probably the biggest pain in the butt to swap of most things you list....thanks for the ideas!!

TronGod

 

Order the water pump at www.stewartcomponents.compart# 13123 and you can order the "Perma Cool" fans at either www.Summitracing.com or www.Jegs.com The water pump is Very Easy to do if you have the serpentine belt.

 

i would put the 180* stat in there with two 1/8th inch holes. put 50:50 mix of coolant to water. wiring your fans to come on whenever you want is simple. let me know if your interested in some methods to do that. there is also a tech article. 220 is normal. 240+ isnt