Radiator/Cooling Problems (sorry - long)

BlackSC

Registered User
Okay...

I'm half lost about what to do next on my cooling system. My 93 has been overheating - to the point of steaming, once - and ever since I've been replacing parts trying to find out what isn't working right. So far, I've replaced the water pump, put in a 180 tstat, replaced all of the hoses, flushed the coolant and replaced it with 50/50 coolant/water. I'm also about to put a new coolant temp sensor in though I don't expect it to do anything. I'm looking at the radiator now - it definitely seems corroded inside the cap on top, though it doesn't leak.

The car won't run 70 with the air conditioning on (been 90-100 degrees lately) without trying to redline. It seems to do fine at low speeds in town though. I'm also pretty sure the fan is working fine, at least it does when I run the EEC self test. The car is a 93 5 speed. It has 77k on it and is completely stock.

I can get a new radiator for 180, shipped. Does this seem like a reasonable next step? I don't know what else could be causing these problems. Also - is the stock rad. a 2 core? Is there anything specific I should make sure the new one has? I've searched and read along the terms of recore, radiator, etc. but this is still kind of unclear...
 
You have checked for leaky HG's havent you?
If the HG's are good then yes the radiator is plugged.
My 90 radiator looked real good looking down the filler neck, but theres a baffle plate in mine that blocks your view off the tube ends so I couldnt see how bad it really was. Tore the old one apart and it looked like concrete in there.
We have hard water in our area. Lotta limestone in it.
 
Unsure on the HG's...have had the car for a year (8k miles) and it seems that they are ok but don't know. I've never noticed any smoke out of the tailpipes or anything like that...but I'm fairly certain that there is still an invisible coolant leak somewhere. Not necessarily in the block though. I've also never seen signs of coolant in my oil or bubbles in my oil or bubbles in my coolant, so not quite sure on that point either. I do have a vacuum leak or something that is causing me to max boost at 8 psi. Don't know if this could be related to leaky head gaskets.
 
I'd pressure test the cooling system before I did anything else. You can borrow the tool from Autozone if you dont have one.
Its called a Cooling system leakdown tester.
Youll find the leak then, that may be your problem.
 
WHAT TO DO ???????????????

I HAD AL THE SAME PROBLEMS CUT 14 WIRE AND GUTTED OUT STAT ............USED A 1/2 WASHER HAS 9/16 0PENING................WORKS GREAT................CHECK OUT TECH SITE USE SEARCH FOR OVER HEATING FAST FREDDIE:rolleyes: :rolleyes: :cool: :cool: :D :D :D
 
Kind of already did that...I think

I did have a local shop pressure test my radiator (while in the car). Don't know if this would mean they pressure tested the whole system but at any rate they found no leaks. That was free...so maybe I'll go back and have them check again. What's the procedure like to do this once I have the tool?
 
It sounds like you have air in your coolant system. How did you fill the car with coolant? Did you unscrew the bolt by the thermostat housing (it is the one with the white cap on it)?

If you were having cooling problems before this, then I would say the rad is clogged. Try venting the coolant system first, before spending $180 on a rad.

Later
Ken
 
Definitely did that...so thinking radiator

Yeah...I think I did that right - take the air vent by the tstat off while filling, then reinstall before the first start. Fairly certain that's not the problem, besides when I first got the car and had to fill coolant I did it that way without any overheating results. Kind of tempted on that radiator...
 
For what it's worth, just bought a great 93 SC 5-speed from a guy that really took care of it, 94K on it and he had put two radiators in it before he installed a Griffin radiator with a fan switch. This thing cools great! Sounds like you hit everything else, if it's not the HG that is what I would go for. We drive in the heat all the time down here.
 
just pressure testing the radiator is not sufficient after all that you've done. I would have to guess that you have insufficient flow through the radiator. A radiator shop might be able to test for that, some can use a thermograph to see if there are hot spots in the radiator where coolant is stalling.

one thing that is interesting is that it's fine in town but not down the highway. that would make me wonder if it's simply the air dam missing under the bumper. With that missing, at higher speeds, there might not be enough air flowing towards the radiator. This seems more likely since around town it is just fine.
 
The leakdown test I was talking about tests the entire cooling system on the car. The rad and all connections, heater core system, all waterpump connections, water jacket of block and heads and of course the HG's.

I had a HG one time with a tiny leak letting HOT combustion gasses into the water jacket and the engine would heat up just like he described. I'm not saying its his problem but it could be.
My engine would not get hot below 55 MPH and ran perfectaly fine, but as soon as I went over 55 you could watch the temp gauge climb until I backed off below 55 and it would cool back down. Its worth checking into.
 
Any ping?

Hey Black by chance are getting any part throttle detonation or ping?

I might have a similar problem with pinging and boiling coolant.

If my engine builder comes to that conclusion, off with the head.
 
If you have a vacuum leak, get that fixed. You are running the engine lean, creating a lot of extra heat. The cooling systems on these cars are marginal at best, when they get old and dirty they can't handle the extra heat.


Aaron
 
BlackSC, I had the exact symtoms as you in the past month. Air temps here in Az were running about 115+ at the time. My 90 SC got hot at highway speeds and climbing hills but not around town. I've had this car since new and this was a new problem. I did all the usual maintenance steps with no improvement. Although the stock air dam was there and in good cond, I installed two Pontiac air dams with no improvement. The only thing left was the radiator itself. My original, visually looked clean and in good cond but I replaced it anyway with one from Radiator Express. Problem solved. It now only gets to the "O" climbing long hills at 110 degrees and between "N" and "O" at 85+ mph. I have 148,000 miles on it and even though I have changed coolant regularly the stock radiator must be partially plugged (I haven't had it checked). Good luck, John
 
FIXED!

Okay so I finally got tired of wondering about whether or not the car was going to make it down to the city so I ordered me up a radiator (180-all metal 2core) and threw it in earlier today. Took the car out and ran it pretty hard showing it off to a couple of guys. Went about 20-30 miles in ~80 degree weather on freeway/hiway with the ac on full blast and it never hit the r in norm. Cold enough for me!

Another problem fixed by sccoa forums. Thanks guys!
 
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