LB7: oil in coolant

1chevy02

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Jun 23, 2009
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A friend of mine is getting oil in his coolant, but no coolant in his oil on his 04 lb7. Besides headgasket what can cause this? I don't think its the hg, but we are gonna do a compression check to be sure. I know the oil cooler can cause this, but how would I go about checking it.
 

LBZ

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Jul 2, 2007
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Oil Cooler. Had it happen in my LBZ back when it was almost new.
 

LBZ

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It's a bit of a giant cup of suck to do in the truck. Going off memory here but I believe you will need a couple o-rings for the filter base and gaskets for the coolant tube and on either side of the cooler. And it's tricky to get it all together and not have either a coolant or oil leak after. Take a good look at the coolant pipe too. These things do rust and leak-usually after the cooler gets changed from what a GM mech told me once.
 

wikdlmm

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Jun 27, 2008
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Oil cooler is not that hard to change as we had to do it on our lb7. But I believe ppe makes a oil cooler delete still..
 

Slick

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Jan 9, 2007
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Just had this happen to my truck. We started it for the first time about a week ago, and it was getting oil in the coolant BIG time. Took the one off my old engine and resealed it with the gray sealant from GM. The dealer doesn't sell the two metal gaskets on the inside, or the larger metal one to seal the two halves, so I'm hopin it will stay sealed. A new one is around
350$ so I'll be doing that if this one starts leaking. I installed it last night, and I think it solved it.

Also, the cooler for the LMM and Lb7 are slightly different. The LMM cooler I took off uses an O-ring to seal the two halves, and the LB7 uses a metal gasket. They will both bolt up the same on the block, however.
 

Slick

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Jan 9, 2007
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It seems to be. Haven't got to mess with it too much the last couple nights, but the night I put the cooler back on I drove it up the road a few times, and the oil seems to be stayin in the right place this time. Sorry man, I thought I text you about it...
 
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