Overheating?

[alexmanners]

I am having some issues with my Suburban and the engine overheating, but it's actually a really strange problem. It was just serviced about 2-3 months ago to get the wheels realigned and have the oil changed, fluids checked, etc so I don't know if something got overlooked or what, but here's the problem: After starting the car the engine will be at a decent temperature, but after driving for maybe 5 minutes the temperature gauge goes off the chart; HOWEVER, just shortly after it skyrockets (maybe 2-3 minutes more), it goes back to normal and there are no more problems. It happens intermittently so any ideas or help is greatly appreciated!

[prizrak]

Is the fan running? If you have an electrical fan you might have either a faulty sensor or a faulty relay.

[tigger]

I'd guess it's just a faulty gauge or sensor. Just driving around for 5 minutes shouldn't be enough to overheat the engine.

[alexmanners]

Alright! Thanks a lot, I may take it in just to have it checked again, but I won't pay if it's really expensive to fix

[NotLaw]

what year is the surburban? if its new enough to have electric gauges then check all the grounds in the electrical system.

I had this kind of think happen to my Safari (Astro) van, after about 5 min of driving the temp gauge would max out and stay that way.
did everything i could think of to fix it, and ended up temporarily installing an aftermarket gauge, which proved that i was getting a false reading... left the after market gauge in since i could not afford a new guage cluster...

fast forward to a year later, battery died, and when i was pulling it, i noticed that one of the small ground cables was loose... tightened that up and it fixed everything lol

[alexmanners]

Originally Posted by NotLaw

what year is the surburban? if its new enough to have electric gauges then check all the grounds in the electrical system.

I had this kind of think happen to my Safari (Astro) van, after about 5 min of driving the temp gauge would max out and stay that way.
did everything i could think of to fix it, and ended up temporarily installing an aftermarket gauge, which proved that i was getting a false reading... left the after market gauge in since i could not afford a new guage cluster...

fast forward to a year later, battery died, and when i was pulling it, i noticed that one of the small ground cables was loose... tightened that up and it fixed everything lol

It's a 1998 or 1999 model, so I'm not sure if it has the electric gauges or not. How would I go about checking that?

[NotLaw]

that new the gauges are almost certainly electric, and prob controlled by the computer...

as for checking it, theirs a way to do it with a Multimeter, but i am afraid its been a while since i learned exactly how lol...
I suppose a brute force method would work, just pop the hood, make sure all the bolts on the frame, body, battery, etc are tight and there are no loose dangling wires... (this prob would not hurt anyways)

Like i said, when i found that prob on my safari, I kindof accidentally stumbled onto it when i was fixing an entirely unrelated issue lol


mebby a Google for "Finding Bad Electrical Grounds"?

I am sure one of the more experienced shadetree mechanics can help more

[Seasonone]

Could be a thermostat about to go out too, holds the water in too long, it gets really hot than the added pressure is enough to force it open and than it functions like it's suppose to. That is if everything else checks out or you feel it's time to flush the coolant and get a new thermo anyways.

[73GMCSprint]

You might have an air bubble in the cooling system.

[Seasonone]

That too, "burp" the system. Best part is that's a free and simple thing to do.

[Alex_0700]

I would guess it's a thermostat problem, but it could also be a water pump about to give out. Slightly different concept, but the same thing happened to our boat and it turned out one of the vanes on the water impeller was broken. But instead of overheating, the temp was spiking up and down like you are describing. Check it out as soon as you can because these sudden temp changes are not good for long-term life of the engine.

[alexmanners]

Okay I just drove the car again and everything seems to be going wrong now. Now the temperature is staying high (and it isn't just the gauge, I popped the hood and almost died from the heat coming out), and the right front wheel (brake?) sounds like a meat grinder on occasion. I think my beasty may be on his last leg...

[Adunaphel]

Sounds like your thermostat decided to finally die. try to (CAREFULLY! PROBABLY HOT!) feel the temperature of the hose leading from your engine to your radiator. If it feels anything other than boiling hot, your thermostat is broken. Upside to this is that a thermostat is generally dirt-cheap and on most engines takes less than 25 minutes to replace.

[Spectre]

Sounds like it needs a cooling system flush, new thermostat, and either a wheel bearing or brake service. Don't drive it that way, have it looked at immediately - even the venerable Chevy 350 can only put up with so much overheating before it cracks a head or blows a headgasket, at which point the repair cost will probably exceed the value of the car.

If you repair them in time, it shouldn't cost too much; your Suburban could soldier on for a long time with regular care. Of course, all the internal plastics will fall apart as will the trim, but the basic vehicle should continue to work...

[alexmanners]

Yeah the thing is I'm really weary of putting more money towards repairs as of now because over the past 2 years I have had it serviced twice and the total cost for both of those exceeded $1800. I honestly think I could pick up a new car for the cost of the future repairs I know I'm going to need... I'll bring it to the shop and see what the mechanic says and if the price is too much to swallow I'll just blow the car up.

[Spectre]

Learn to do your own wrenching. Replacing the thermostat on a Chevy V8 takes about 30 minutes (most of which is waiting for the coolant to drain out) and costs about $20. Flushing the system takes about the same amount of time and costs $50 or so.

Doing wheelbearings is a pain, but IIRC that car uses sealed units and you can swap those out in an hour or so for ~$200. Brakes are even cheaper.

[alexmanners]

Oh that actually doesn't sound too bad... I'll definitely be looking that up later depending what the mechanic says. Thanks for the help!

[matt2000]

This might sound obvious but I haven't heard any mention of checking the coolant. Do you regularly check coolant and oil levels? Is there any coolant in there?

[Spectre]

98/99 Suburbans have a low coolant level/low oil level warning system that is multiply redundant.

[alexmanners]

Originally Posted by Spectre

98/99 Suburbans have a low coolant level/low oil level warning system that is multiply redundant.

Originally Posted by matt2000

This might sound obvious but I haven't heard any mention of checking the coolant. Do you regularly check coolant and oil levels? Is there any coolant in there?

Yeah I already checked all that and since it was just serviced, I'm fairly certain that the coolant level is still fine.