Oil and coolant mixed - How to diagnose

A co-worker has an issue with a 2002 Chevy Blazer where the oil is mixed with the coolant. My understanding is the usual causes of this are blown head gasket, cracked cylinder head, or cracked engine block. The car belongs to a high school student who has to pay for this out of his summer job earnings. (Meaning mostly broke) If the cause is a head gasket, they’ll probably fix it. Cracked cylinder head makes fixing it iffy. A cracked engine block probably means junking the vehicle. Is there a fairly inexpensive way of determining the cause?

On this engine the most likely cause is a failed lower intake manifold gasket. As long as the engine has not been driven too far with coolant in the oil this can be fixed for $600-$800, depending on where you are.

99% chance it’s the intake manifold. This is a know problem with many GM engines of that era.

I fixed one of those GM intake manifold gaskets for less than $300. Some shops have done so many of these that it’s routine.

Is he going to have this done or do it himself? Also, do you know if the engine was badly overheated?

@“MY 2 CENTS” Backstory on this situation. The owner is a 16 year old high school student using the vehicle to get to part time job. He was given the vehicle by a relative who took mercy on a good kid who needed transportation for his job. Don’t know much about the maintenance history other than the new owner has spent all his savings into putting brakes and new tires on it. Don’t think the engine overheated in recent history, but have no clue about what the prior owner did.

The parents are trying to decide if it’s going to be a money pit and cut their losses, or if it’s worth fixing.

The car was given to the kid with no strings attached. Needless to say, the first expenditure should have been a mechanical inspection, but parents didn’t think it necessary.

The kid is amazingly responsible and level headed, but isn’t experienced in making these kinds of decisions. He’s probably going to have to have the work done. He has access to a great area to do the work, but no knowledge of how to do the work. Another relative has helped him out by doing some of the simpler work, but not the bigger jobs.

Thanks to everyone for the information. I’ll pass it along.


Drain The Chocolate Milk in your oil pan…and replace those INTAKE MANIFOLD GASKETS

A great project to do on your own… Its actually a little fun. Ive done so many its silly…very common failure.

BEWARE the bolts in the 4 corners however… I spent a ridiculous amount of time trying to drill out a broken intake bolt before. As if that werent bad enuf…The EZ OUT SNAPPED OFF In there as well…
Ever try to grind out or drill TOOL STEEL? NOT FUN

But otherwise…EZ job to do



Actually it was asemaster who first pointed it out…I was just confirming what he said.

ASE HAS NAILED IT… LOL I second and Third that vote