Coolant In Oil

[fatratchevy]

Friend has a '99 Silverado and its been loosing coolant for the past 6-8 weeks. We have been unable to find the source of the coolant leak (none on the ground), and he's just been topping off the radiator every 2 weeks (about 1-1.5 quarts). Truck runs strong, no missing, hesitation, overheating, smoking or anything abnormal.

 

Now he informs me that he had the oil changed and the service guy shows him the cap with a milky film on it. He immediately took it to a mechanic who said it was probably a head gasket, but did not run a compression test to verify (don't ask me why not, I have no idea). Now the truck is at the dealership and the service writer said that it could be the intake manifold gasket, or the water pump.

 

First, has anyone experienced this, and if so, what was the root cause.

 

Second, there is no oil or coolant running through the intake so how could it be the intake manifold gasket?

 

Lastly, how could the water pump leaking cause coolant in the oil? Am I missing something here?

[pennzoil29]

I would lean towards intake manifold gasket. I have a 1999 C2500 with a 5.7 and the same thing happened to me. I was about 50 miles from home on a really cold day and fired it up to go home and wow, the noise she made, sounded like the whole top end was going to come off. The culprit was the inatake manifold gasket. Make sure you get a good felcro to replace it. Hope this helps.

[pennzoil29]

sorry dude, I meant felpro, not felcro

[fatratchevy]

sorry dude, I meant felpro, not felcro

 

 

If memory serves, the old 5.7's had a coolant passage in the intake manifold which (if leaking) could drip down into the lifter valley causing coolant contamination to the oil. The LS series motors have no coolant passage in the intake, plus a lifter valley cover that blocks off the intake to the lifter valley. This is why I am so perplexed, maybe the service writer was unaware of this and is thinking the 5.3 was similar to the old 5.7's. . . . .

 

Thanks for the reply.

 

(notice no coolant passages in the head-to-intake mating surface)

 

 

 

(note the lifter valley cover)

 

[gibbons948]

#1 coolant and oil...bad news.

 

#2 water pump???service writers dont know sh@#$!