I need some thoughts. I have a zz3 (similar to a zz4 crate engine) that’s getting coolant in oil. There is no smoke, all the spark plugs look good, no bubbling in the radiator. I suspected an intake manifold gasket and replaced it last night. Changed oil and filter, fired up and 10 minutes later she had chocolate milk in the oil pan again. What could it be?

 

Welcome aboard thirdgen.org.

Sounds more like coolant in the oil (Topic line say oil in coolant). Cracked block is a pretty common cause of that. Some people say blown head gasket, but I've never seen that actually do it.

When you had the intake off would have been the best time to check for the cracked block. The lifter valley is where they tend to crack.

 

That's what I meant- coolant in oil. I didn't pay very close attention to the condition of the block since I assumed it was an intake gasket. I'll be taking the intake off tonight so what should I look for? I've never seen a cracked block before so I'm not sure what it would look like... If that is what happened how do I fix that?

 

As was mentioned, it could be a blown head gasket. It could also be a cracked head. And the crack may be too small to see with you eyes. Usually, it requires a process called magnafluxing to find the crack. If you didn't notice your engine missing, chances are it's not a gasket. If it's either a head or the block it can be fixed, but usually isn't worth the effort. Plan on new pieces.

 

Pulled one of the heads off and here is what I found. There appears to be a crack in the gasket between a water jacket and the area of the head where oil drains down into the lifter valley. Does that look like something that would cause water to get in the oil? Picture is attached. While I'm at it- I noticed that one of my exhaust valves is not as white as the others, what does that mean?

 

Possibly. What you don't know, and can't tell is whether or not that happened during removal of the head. I'd definitely get that head fluxed, though. Have the shop check it for flatness, too.Not much. It's just deposits that build up over time as the engine runs. Think the Shell Nitrogen Enriched commercials.As long as you've got the heads off, now would be the right time to have a valve job done, though.

 

Pulled the other head and found the same looking crack in the head gasket as the first one. Both heads are at a machine shop getting pressure tested, keeping my fingers crosses. Should I do anything to the lifters while I wait?

 

Look at the side of the lifter valley, between the lifter bores and where the head mounts.

I've had two SBC's cracked there.

 

Any thoughts on cleaning the lifters?

 

Probably not worth the effort.

 

Assuming that the heads check out ok by the machine shop, what head gasket would you folks recommend? 12557236 were the original GM gaskets used on zz3, I wonder if I should stick with GM or a different brand?