01 Denali Overheat

[aaford72]

My 2001 Denali has an overheat issue when the AC gets turned on. Will rise from 210 to about 245.

Turn AC off and will slowly start to cool back down. Already did a coolant flush and new thermostat in the past 10 days and still having the issue. Took it to a garage they initially thought it was intake gasket. Opened up and found that it is not the case. Now they believe it is head gasket. They called and said that they see a small coolant leak coming from back of block when under pressure (18 pounds for over an hour). They want to replace head gasket and have head and other components machined (cost over $2500).

Does this all seem correct or are they trying to take me to the cleaners?

Can I just drive without AC or do you think that there is another issue with AC causing the issue?

Thanks!

 

[about20ninj45]

If your mechanical inclined you can do the head gaskets yourself for about 300 or so. I'd check to see if your fans are turning off when your running the AC. Do you have a clutch driven fan or electric fans?

 

[Danny3737]

The first thing I would check is the fan clutch. They are known to go bad.

 

[about20ninj45]

If your mechanical inclined you can do the head gaskets yourself for about 300 or so. I'd check to see if your fans are turning off when your running the AC. Do you have a clutch driven fan or electric fans? You wouldn't need the heads machined unless you warped them, which is rare in most cases.

 

[#1taho]

What style fan do you have ? Electric or clutch fan ?

I would think it's a fan problem!!
These trucks don't really get blowed head gaskets. So I would be surprised. But you could have another coolent leak. Coolent hose at the back. Or byroads hose. Maybe even a frost plug. But start with the fans. That's were I and most of us would start

 

[afpj]

If that garage suspected the intake gasket as part of a cooling system issue, I would go to another garage. These vehicles have dry intakes, meaning no coolant goes through them. They do not know what they are doing, Runaway.

 

[aaford72]

I went to the garage and looked at it myself. There is a very slight leak coming from the backside of the motor. At this time I have asked them to put it back together and I will look for a second opinion. They claim that the small leak causes air bubbles and is why it will start causing the temp to go up. I have never heard of this myself.

It is a clutch driven system. They claim to have tested the fan clutch and it is strong. Not sure what to check next.

 

[bottomline2000]

How old is your water pump

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[afpj]

The air bubble thing is real, so they're not FOS there. As far as coolant on the back side of the engine, the only place I can think of off the top of my head is the coolant to the heater hoses spraying down. That would be a fairly common issue depending on the age and maintenance of your vehicle. However head gasket leak is also a possibility but that'd be pretty rare as others have said. Good luck

 

[aaford72]

How old is your water pump

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Not sure. I have only owned the yukon for 3 months. They did say it looked good.