I have been have a problem with my 94 Z28, for some reason it doesnt like to stay cool, Driving in the city it seem to be alright, but on the high way it gets really hot, i have both fans hooked up to constantly run, new radiator due to crack in old one, new thermostat, new water pump, new temp sensor on water pump and on block but still not working, doesnt seem to be leaking any anti freeze or have a cracked head or bad gasket, Any Ideas, i miss driving my car even though its parked now til winters done.

 

Did you purge the cooling system after you replaced everything? you may have a "bubble" in the coolent...

 

I second the bubble theory. Try the purge.

 

yeah, it was happening to me after i drained the radiator. opened it up w/ a few redline shifts and it blew the bubbles out. back to normal.

also, since getting pcmforless.com tune, temp nevers goes above 1/4 mark, even in traffic.

used to routinely go to half way and little above

 

uhm.. you're supossed to purge the coolent system with the valves on the hoses off the waterpump... highest point in the system...

 

Just for some info, may not be your problem but maybe a possibility.. Every camaro I have ever seen when some one bought it has green coolant.. Mine did aswell.. THe temperature when it was bought way exceeded the middle mark and I couldnt stand being paranoid all the time.. I noticed after I leardned that our cars are supposed to have "dexcool" orange coolant in there that mine had green... I changed that out did a full flush of the block and of the resevouir tank and put some "super cleaner" in there and I dove it for a few days with the cleaner in there and just water and when i took out the water and cleaner i had put in there the color of the water was unidentifyable,lol.. I flushed it again and then added coolant (the right kind) and i didnt have a tune or anything and my car didnt even go above the middle mark in traffic... My buddy crazy95Z is in the process of doing this now, aswell his car came with green coolant..

 

Purge your cooling system. Thats your problem. Turn your car on, open the copper screws (one on therm, one in front of radiator on a T *maybe not your year*) that will bleed the air in the system. It should SPRAY OUT, not just drip out. Try to keep them both open, then alternate bleeding each screw. Add coolant if you need it, just dont add to much or else it will overflow out of the cap and you will think you have a leak. Let us know, thats the TRUE way to get rid of air in the system. The method you tried works, well kinda, but it doesn't get all the air out, only alittle.

 

I also have an over heating problem with my 94 z28. I have replaced the water pump. and the thermostat, the thermostat made it run cooler for longer periods of time but still when i am in traffic it seems to get up to and past the 3/4 mark. I think that i will try what CoUnTryMuZiCZ28 has suggested with the different type of coolant next. I have released the air from the system. and it seems to be about the same. My car runs at a good temp when i am moving but when i stop it seems to overheat. I am working to get my car to run under the half way mark. which is how i think it should run. If anyone has any more suggestions please let me know.

 

Dexcool was stock on post 1995 camaro's. Anything prior was the green stuff.

 

so what you are telling me is that in my 94 camaro i should not use the orange coolant it should be the green?

If so then i do not know why my car is running hot after driving it for about 10 mins maybe 15 and then when i am at a stop it begins to over heat. I have tried removing all the air from the system 2 times that did not make a diff. When i replaced the thermostat it was cooler for a while but still did not stay that way. I am not sure why over a small bit of time its over heating. using the orange coolant sounded like a good solution but i am not sure if that will work.

just a question how did that high flow cat help you out did it make a big diff? and when you used that 160* thermo did that make it stay below the half way mark all the time ?

 

All I'm saying is that your car came stock with the green stuff. Some people change to the Dexcool because it is less corrosive. I was going to switch to dexcool but the dealer reccommended I keep it green. I don't think switching will cure your overheating problem though. When you say overheat, are you well into the red? Do your fans come on? Before I got my fans programmed to come on earlier, my car used to get close to the red at lights or in traffic. Now it stays much cooler. Do your fans bring the temp down when they come on?

 

In regards to the 160* thermo, my car runs at the second line at cruising, instead of the halfway mark with the stock thermo. I got a new cat because mine was gutted by the previous owner and i failed emissions. The car ran a lot better, and did not sound as raspy. I went with Hi-flow because of the cost. Putting on a new stock converter is pretty expensive.