I have the opportunity (?) to purchase a 98 Olds Bravada for around $500. Seller says it's got a blown gasket, but not sure if it's the LIM or a head gasket. He says it started producing a lot of white smoke suddenly but did not run hot, so he parked it and sure enough there was coolant in the oil. The intake is off and theres a spot toward the rear where it looks like the gasket failed. I'm just afraid it could still be a head gasket. How can I tell for sure?
When the LIM failed on my 02, it didn't smoke or run hot. It just stopped running. And my plugs were clean. This lead me to believe it wasn't a head gasket so I took the chance and did the LIM job. Turns out I was right. So I guess my question is, how can I tell what failed?

 

The LIM gaskets fail in multiple ways. I've seen them just seep oil down the front or back of the block, coolant into oil, coolant into an intake port, and often coolant into the oil and intake port at the same time. When that happens it'll give all the tell tails of a head gasket; burning antifreeze and antifreeze mixed into the oil. So you may very well be lucky and it only be the intake gasket leaking into both the oil and intake port.


At this point with the intake off and coolant system open, the only thing you can really do is a compression test across all cylinders and see if one is drastically low or won't hold the compression as long as the other cylinders.


The only other test for a head gasket failure is a leak-down test, but this is performed on the coolant system and with it being open with the lower intake being off, it's not possible to perform the test, unless you could find a way to block and seal off the coolant passages on the head surfaces, like putting the intake back on :P




I would say just replace the intake gaskets, change the oil, top off the coolant, and see what happens. Worse case scenario, you have to pull it all back apart and replace the head gaskets and intake gaskets again...

 

This is pretty much what I figured.
Also found a nice blue 4 door blazer for $500, disassembled, needs heads. Might go for that one instead, as the job is halfway done. Thanks!!