Thread: Overheating issue - absolutely stumped (Done almost everything)

Car could go to red if i let it. Heat is hot in car. I cant help but think if the rad was clogged why did thnigs seem ok when i pulled the t stat? How can i test the rad?

Leave the thermostat out and open the radiator cap... turn on engine and watch for coolant flow.
If you see nothing moving then you know there's no flow.

im having this same problem.... except without a tstat i still run hot... but i gotta 180 tstat

Originally Posted by thomas mcnulty

like i said, i had the same issue on a 79 z28 i had. it was overheating really bad so i replaced the tstat, when that didn't work i fully rebuilt the engine (with a ton of goodies) and when i got it back on the road and it was still overheating i wiped out my brand new cam and all my bearings. after the rebuild (again) i replaced the radiator and never had the issue again.
before i rebuilt it the first time i ran it without a tstat just to be able to commute to work in it (it was not overheating minus the tstat)

K, going to pull that prick out this week. Once I get it out can I use a hose or something & flush the hell outta it through the filler neck? do i have to be careful on the pressure (ie. fins getting destroyed)?

Best way to flush rad while in car? Can i put a hose down the neck and blast?

prestone and other company's sell radiator flush, you can put that stuff in, run car as directed, then pull the lower hose. put your hand over the opening or hose depending witch side you pulled, water pump side or radiator side. fill it back up with a hose, and then let if flow out the opening a bunch of times.

i would think if the water drains slowly, you have a real clogged rad and may need to replace it.

Just went outside pulled lower rad hose and let rad drain. Inserted garden hose in filler neck and blasted away until clear. Did not seem slow. Then put hose into upper rad hose and blasted. it took about 3 seconds and water came flying out. Then connected lower, filled rad and LIM. Decided to start car and a raging force of coolant blew up from inside LIM. So seems like flow is there.

What next besides getting a flush kit?

Fired up again. Overheated and nothing flowing through upper hose. Plus fans kick on blowing cool air so heat cant be going through rad. I drilled six holes in the t stat and she is running ok'ish not overheating. Going to get a third thermostat but different manufacturer.

I don't know how many times people have to tell you to buy a new radiator................seriously!?

sucks, sounds like a bad t stat, maybe remove it and see if it over heats.

Update: Different t stat and different manufacturer still problem. Swapped out rad for another used one i got for free from a car where it was working just fine. Car is over heating just a tick less but temps all over the place and i continue to have the issue with coolant flow and bleeding. I crack bleeder rev up and hold and zero coolant will come out. Going to have to drop off at a shop i guess. Any last ideas? Thinking air but i cant seem to get it out.

i would remove the t stat, put the housing back on, then take the upper hose off the rad, and see if you are pumping coolant out the upper hose, if not your water pump is most likely dead. rotted impeller.