1999 OBS Yukon losing coolant, help

[99GMCZ71]

I have an 1999 OBS Yukon with the 5.7 350 that is losing coolant somewhere. There are no visible leaks, and nothing is left on the garage floor at night. Someone has said maybe intake gaskets. Have any of you guys had this problem? Any suggestions?

Thanks

[TimTim]

I have an 1999 OBS Yukon with the 5.7 350 that is losing coolant somewhere. There are no visible leaks, and nothing is left on the garage floor at night. Someone has said maybe intake gaskets. Have any of you guys had this problem? Any suggestions?

Thanks

 

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I have also heard that. I friend on mine is an ASE Certified Master Tech, Over educated, extremely meticulous and he swears that Dex-cool is the worst coolant and will eat gaskets and seals???? All of his personal vehicles have been drained, flushed and refilled with the "green" stuff.

[Shawn T]

I have an 1999 OBS Yukon with the 5.7 350 that is losing coolant somewhere. There are no visible leaks, and nothing is left on the garage floor at night. Someone has said maybe intake gaskets. Have any of you guys had this problem? Any suggestions?

Thanks

 

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My parents own a 99 Escalade(same truck) and had the same problem. It was intake manifold gasket. It leaked from the rear so it was not visible either. This year of 5.7L is famous for bad intake manifold gaskets. I would change it myself. The dealership will charge you an arm and a leg in labor costs. The part is less than $20.

[intruder217]

Mine was a blown head gasket after 112,000 miles. Try not to get sucked into the all the bad press on Dexcool. Do your research, use it properly and it will serve you well.

[sub5]

I agree, DEXCOOL is not bad, it's lack of maintenace and not following instructions. DEXCOOL doesn't eat up intake manifold gaskets, the problem is from GM itself. A lot of intakes where over tightened during assembly causing small cracks in the gaskets. Not a problem when new but with time the gaskets fail.

[mcreyaufmiller]

The problem goes further than overtightening at the factory. The problem is with the design of the intake manifold, there is a water jacket in the manifold that terminates directly onto the heads. Pressure builds up at this point and the gaskets blow. From what I understand Chevrolet has fixed the design flaw on newer vehicles.

 

Mike

[ManyCamaroz]

I have an 1999 OBS Yukon with the 5.7 350 that is losing coolant somewhere. There are no visible leaks, and nothing is left on the garage floor at night. Someone has said maybe intake gaskets. Have any of you guys had this problem? Any suggestions?

Thanks

 

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I also have a '99 OBS Yukon and had the same problem. Check your radiator cap. It might be leaking slightly and not leaving a trail. The system was pressure tested and it was determined to be the radiator cap. I put a piece of tape on the overflow tank, marked the level after setting overnight and I'm keeping an eye on the level. I took it in for warranty suspecting a head gasket failure because I had to add about a 1qt. of coolant every 500 miles. They said it was the radiator cap. We'll see..

 

I had to replace my IM gasket at 48k due to a coolant leak at the front of the IM.

[chevroletmb]

in regards to these people who drain the dexcool and fill their vehicles with

green coolant. if you use green coolant in a duramax the coolant will eat away

at the heads. we had one customer find out the hard way