Mechanics

COOLING SYSTEM OVERHEAT

1994 Chevrolet Beretta • 4 cylinder FWD Manual • 120,000 miles

Upper radiator hose blows off. Bought a new one and replaced. Weeks later, car starts overheating. Told to replace overflow reservoir because it's common for plastic threads to strip. New overflow reservoir and new cap. Still overheats, and coolant spews from under radiator cap. Replaced thermostat and thermostat seal. Drained radiator and flushed with Bars Radiator Flush Kit. Refilled with prediluted 50/50 antifreeze. Still over heats and still spews coolant at radiator cap. Took radiator cap to Autozone and got a new one. Still over heats and spews. Took back to Autozone, they claim that the threads look fine and cap is in perfect condition. They told me it sounds like air in system. I bled the system. Still over heats and spews. Found more info on bleeding air out. Removed overflow reservoir cap, opened bleeder valve by the thermostat, started car. Constantly kept coolant level in reservoir at absolute max, while letting the car run for 10-15 minutes. Closed bleeder valve. Car still over heats and spews coolant. When car is driving in city, the car runs perfect for about 30 minutes, unless I'm driving up hills, then 15-20 minutes, before overheating. I drive on interstate to work; car will stay at 1/4 mark on temp gauge until I leave interstate, where temp will rapid move to 3/4 mark, and coolant can be smelled, and spews when parked. When idling, car runs fine, until I rev the car; at this point car will get to 215 deg F (a sliver past the 1/2 point on temp gauge) fans kick on until temp gauge is at about 3/8, then they turn off and coolant spews out of reservoir at the cap. The coolant temp sensor works wonderfully, the fans work wonderfully, I have inspected the water pump (no noises, no play in the pump when rocked so no bearing wear, no leaks from weep/vent holes), new thermostat and seal, new upper radiator hose, all hoses feel warm or hot to the touch and have pressure in them (hard to squeeze). I don't what else could be the problem. I am thinking I need a new radiator, but am doubtful that it will fix the issue, it almost seems like coolant doesn't get to the radiator at a certain temperature. Any ideas on what this could be caused by? Or how to fix it?
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Fackiner
July 10, 2011.




Triple check the radiator if its clogged-feel the fins for cold spot at all areas should feel the same temperature if okay-bring her in and get it block and pressure tested-

Tiny
Rasmataz
Jul 10, 2011.
I vote to turn rasmataz's suggestions around. Get it checked first for a leaking head gasket and avoid all the other misleading symptoms. I think you're trying to fix the results, not the cause.

Caradiodoc
Jul 10, 2011.
Okay, what I withheld from you guys is that before my upper radiator hose blew off, my car overheated unexpectedly and was stuttering when I gave it heavy gas. I had a compression test done, and cylinder 1 and 2 were low. I had a hydrocarbon "sniffer" from an emissions tester placed in my overflow tank, and it detected abnormally high hydrocarbons. I also had an oil sample sent to a lab, which found extremely high amounts of water and ethylene glycol (antifreeze). This tells me that the vehicle has a faulty head gasket and a cracked head between cylinders 1 and 2. I used Bars Heavy Duty Stop Leak (crystal glass) as per instructions, and it seemed to fix the problem. No more over heating, no more stuttering. Then the upper radiator hose blew off. Skip forward to the radiator flush and now the heater works again. I purposely didn't mention the faulty head and gasket, because I wanted to see if anyone else suspected that could be the issue. Since 3 of us think its the head and gasket. What can be done other than replacing the gasket and replacing the head? Just the gasket is a $1200+ job and even more for the head, and the car isn't even worth $1200.

Tiny
Fackiner
Jul 10, 2011.
Doc, you can take over this thread its over for me-thanks for the back-up

Tiny
Rasmataz
Jul 10, 2011.
I think I'd look for a second opinion. $1200.00 seems awfully high but I do know there are some GM four-cylinder engines the mechanics hate working on. It's not a given that you'll need a new head. That is only if yours is cracked or warped. Overhead cam engines can't be milled like on older engines. That would still leave the cam journals out-of-line.

$500.00 to $800.00 would seem more reasonable unless I've been out of the industry for too long. You might look into a nearby community college with an Automotive program. We were always looking for live work to give the kids real-world experience. They are well-supervised and the cost is very low, but the trade-off is you won't see your car for at least a few weeks. Also, they will only do engine work while they're teaching that subject.

Caradiodoc
Jul 11, 2011.
Before you spend a ton of money, Your temp sensor that kicks on the fans may be working intermittently. You may want try to wire your fans on a relay so that when the key is on your fans are on. Just my two cents: )
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Tiny
Alansmith1
Sep 23, 2012.

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