Reasons for Vehicle Overheating

[cookiemonster]

Just wonder if you guys could help me diagnose why my 93 GMC Suburban 454 is over heating. The vehicle run for alittle while before it gets to hot and won't start back up again was turned off. Just looking for some ideas. Thanks

 

[619DioFan]

bad t/stat , clogged radiator , low or no coolant , bad fan clutch , blown head gasket(s)

these are some general defects that could cause you overheat prob.

 

[diesel research]

how do you know it is overheating?

 

[General Geoff]

low coolant level
thermostat stuck closed
water pump failure or belt loose/missing
fan not running
coolant line clogged
head gasket failure


those are just a few suggestions off the top of my head, without more information there's not much way to narrow it down.

 

[cookiemonster]

how do you know it is overheating?

Gauge is running why over to the right the high end where it is red.

 

[mech-tech]

With engine hot, quickly touch the radiator, if it is HOT then I would say the thermostat is probably not the problem. If engine runs normal and oil level is not unusually high, then I might rule out a blown head gasket. If engine is HOT and electric fan is not on, then you found your problem. Also make sure you dont see any leaks.

 

[diesel research]

Gauge is running why over to the right the high end where it is red.

probably a good time to verify with an independent source, such as a thermometer. Electric gauges can be quite inaccurate, especially as wiring harnesses get old.

the engine cutting out, may or may not have anything to do with the actual temperature of your coolant.

 

[mech-tech]

Also bad radiator cap would fail too keep pressure on the system. Thats a $5.00 fix.

 

[justanengineer]

The first thing I would check is to pop the radiator cap with the engine cold. The radiator should be FULL, and the overflow tank should also be at the appropriate level.

 

[bullitt67]

How hot is she running? Check the engine oil to see if there is water mixed in, telltale sign is it usually looks like chocolate milk indicating one of the head gaskets will need to be replaced. How many miles are on the suburban? Have you flushed the system since you owned the SUV or know when it was done last? Easy do it yourself fix is to check the coolant in radiator, is it full? what color is the coolant, if it is Rusty brown , I would flush the system and while your at it change the thermostat for piece of mind. Check your radiator hoses for leaks(cracked or dry rot, should be replaced), make sure your clamps are all tight and not leaking. Hope this helps, and what 619diofan said

 

[bobcatdan]

I wonder if this is related to your white smoke you have been seeing. White smoke can equal engine burning coolant which will cause overheating.

 

[cookiemonster]

How hot is she running? Check the engine oil to see if there is water mixed in, telltale sign is it usually looks like chocolate milk indicating one of the head gaskets will need to be replaced. How many miles are on the suburban? Have you flushed the system since you owned the SUV or know when it was done last? Easy do it yourself fix is to check the coolant in radiator, is it full? what color is the coolant, if it is Rusty brown , I would flush the system and while your at it change the thermostat for piece of mind. Check your radiator hoses for leaks(cracked or dry rot, should be replaced), make sure your clamps are all tight and not leaking. Hope this helps, and what 619diofan said

No the oil is clean no milky color or foam whats so ever. Coolant is nice and green no rusty color and it is not going running low. No coolant leak either.

 

[Dimitri]

Check to make sure the radiator fans are working?

Dimitri

 

[cryan]

probably a good time to verify with an independent source, such as a thermometer. Electric gauges can be quite inaccurate, especially as wiring harnesses get old.

the engine cutting out, may or may not have anything to do with the actual temperature of your coolant.

Exactly!! Make sure you confirm your overheating before you rip anything apart! The water going to the radiator from the engine should be between 70°c-90°c (I have no idea what that is in °f ?)
You will smell it if its hot as overheated antifreeze has a distinct smell.

 

[celticbhoy]

Have you had any recent work done on the vehicle, specifically to the cooling system? When I see a car overheat, this is what I look for:

1) Trapped air in the cooling system will cause overheat condition.
2) Coolant is no longer effective. Get a hydrometer or multimeter and stick the red prong in the coolant and the black to a ground. If it reads over 0.4V then it needs to be changed.
3) Thermostat is stuck closed.
4) Faulty radiator cap.
5) Debris buildup in front of radiator/condensor.

Your vehicle has a belt driven fan right?

Obviously check the coolant level and if you have access, do a pressure test on the system and the rad cap.

 

[djjsr]

If you don't find anything wrong with the cooling system, check the ignition timing.

 

[woody 73]

Have you checked your head Gaskets?

 

[ezzzzzzz]

Get an infrared thermometer (cheap from HF at $36). After the truck warms up look a temps at the inlet and outlet of the radiator. Inlet should be close to thermostat rating and outlet should be 20-30 degrees cooler. If that is satisfactory, run it down the road then pull over and immediately look at temps again. My first suspect is a failing clutch fan which will take out the water pump in due time. You could also do a simple leakdown test on each cylinder or pay a shop to check for exhaust gases in the coolant (both would indicate a possible headgasket issue).
By the way, you nevered stated how many miles are on this engine or if you've done anything recently that coincides with the issue. Lastly, temp gauges do fail. It could be the sender or the gauge giving you false info. The infrared will tell you quickly what's up.