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1994 Suburban with mystery overheating

I have a 1994 Chevy Suburban (5.7L V8) that’s occasionally overheating and I’m at a loss as to what the problem could be.

Now, before anyone tries to talk some sense into me with words like “sell,” “scrap,” and “take that pile of you-know-what to the junkyard,” :wink: I should point out that my parents bought this car new when I was 2 and it became my first car almost 10 years ago. I love this car. (But, just so you know I’m not completely impractical, I do have a 2014 Camry as my daily driver now.)

I’m handy but not an expert when it comes to car maintenance: I had no problem replacing my drum brakes using a Haynes manual, but diagnosing engine problems still scares me. So I’ve been bringing it to the repair shop when it overheats. The first time, it turned out to be a stuck thermostat. They replaced that and I was good to go for a few months, until it happened again. That time, it turned out the water pump gave up. One new water pump later, and I was back on the road. That was about a year and a half ago now (and when I bought the Camry).

It still overheats every so often. It’s hard to say exactly how often, since I only get a chance to drive it occasionally with my current job/living arrangement, but let’s say it goes a few months in between it happening. When it does, it’ll just be randomly in the middle of a drive, and if I’m lucky, the warning light will come on before the hose pops off the radiator and coolant spews everywhere. But here’s the weird part. Assuming the hoses did stay on, if I give it a little while to cool off, I can start driving again like nothing’s wrong. And the repair shop can never figure out what the problem is any more (I even let them drive it for 3 weeks once and took it to another place for a second opinion).

Any ideas what could be going on or what I could do about it?

Have the shop check the fan clutch for proper operation.

https://www.rockauto.com/en/catalog/chevrolet,1994,k1500+suburban,5.7l+v8,1302332,cooling+system,radiator+fan+clutch,6812

Tester

4 Likes

Thanks, that seems reasonable. Is this something that’s difficult to check, or are they going to have to do quite a bit of disassembly?

Tester

1 Like

Thanks. I guess my other question would be, with such an intermittent problem, should I have it replaced either way? Is there even anything else left it could be?

There is a long list of “could be” but why go looking for a zebra when a horse is more likely?

On a truck this old, the radiator could be clogged with rust and scale if the coolant wasn’t flushed very regularly. The signs could be obvious to the mechanic that changed the water pump as the coolant would be rather nasty. Since the cooling system has been worked on twice over a couple of years, likely a flush wouldn’t help a lot. Hold off on the radiator until you check the fan clutch.

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if i am lucky the warning light will come on? and you will turn off motor? warning light? like motor overheat? you dont have a temp gauge? thought all chevy trucks had temp gauges
our new civic does not have temp gauge. does have blue cold motor light. i want a temp gauge

What I was really trying to ask is if they check the fan clutch and see it’s working fine, would it be a bad idea to replace it anyway? Since the vast majority of the time, the car regulates its temperature just fine. For example, perhaps the fan clutch is marginal and behaves normally most of the time, but every now and then gets stuck disengaged. Then when they check it (after things have had time to cool and get unstuck), it might be back to normal again for a while. Not sure if that’s possible or at all likely.

I’ll also mention that I’ve had the coolant flushed twice during this time (once when the thermostat got stuck and one other time). Both were when the hose popped off the radiator. And they also replaced all the hoses and checked for leaks the second time (which was not at my usual mechanic).

It does have a temp gauge, and I glance at it periodically, but when the engine starts to overheat, it’s rare that I notice the needle moving before the “check gauges” light comes on. It happens rather quickly. Probably about 15-30 seconds to go from normal temperature to warning light.

If you are OK spending the money, go ahead and replace the fan clutch. There is no downside except the cost.