2008 Suburban 5.3L - does this sound like a head gasket problem?

[Rich_J]

Hello.  I have a 2008 Suburban 5.3L with the tow package that runs normally with no smoke, no coolant loss, no coolant on the dipstick, no bubbling in the overflow tank when cold, no oil mixing in the coolant in the overflow tank, no overheating symptoms and no change in idle or drivability.  When I drained the oil for the last oil change, the last 1/2 qt or so was milky and watery.  The rest of the oil that came out first looked normal.  Since the intake manifold on these is dry, I'm thinking it has to be a head gasket going. I've only had the car for 6,000 miles, so I don't know if it had an overheating issue in the past.  Is there anything else it could be other than a head gasket?  Is there an oil cooler in the radiator that could cause coolant to get into the oil?  Please help me figure this out.  I'm thinking of getting a block tester and seeing if there is exhaust in the coolant.  After that I plan to start compression testing the cylinders.  Any other advice or diagnostic ideas welcome.  

 

Thank you!

Rich

 

p.s.  Sorry, I just realized that posted this in the Silverado/Sierra forum.  Same engine though I think?

[Mikebtte]

Does sound of water in oil. You could have the oil tested and see what it was or you could check your oil on the next oil change.

I have heard of engine that run very little can build up moisture as they never run hot enough to evaporate any water.

Second, I would guess a head gasket or cylinder head issue. Gaskets are not bad to change on a 5.3

[Bikeman]

I think it was earlier years (99-2005ish) but recall from my chevy days seeing cylinder heads crack and leak coolant into the oil, had to remove the valve cover and we would see coolant on the heads. Could be that issue.

[Rich_J]

Thanks for the thoughts so far.  I bought the truck with 114k miles and first changed the oil at 118k (most recent change was at 120k)..  At that point, I got a similar oil drain.  All normal oil at first and then a bunch of milkshake oil at the end of the drain.  It surprised me but I knew that the truck had sat a lot at the end of the original owner’s ownership.  But I bought it from a Chevy dealer and assumed that they has changed the oil, especially since they changed the oil pan gasket right before I bought it due to a leak.  After the first change and all of that milky oil at the end of the drain (more than twice as much as the recent drain after 2,000 miles), I planned to keep an eye on it and do the next change early.  This last change was after 2,000 miles.  

 

I’m wondering now if there may have been condensation left in the oil from the first change that was not in the pan (maybe in the oil cooler?) and I just didn’t get it all on the first change.  I know this is wishful thinking, but now I’m thinking of doing another change after just a few hundred miles to see.  

[Rich_J]

Oh, one other thing.  The coolant level in the overflow tank is not dropping between changes.  That also makes me wonder since coolant would have to come from somewhere, right?  Maybe its fluid from my washer fluid reservoir...haha.