I've never seen this under oil fill cap

[Red Rider]

Yeah... its bad. I had that problem on another truck. What did the oil look like when you drained it out? If it has a real bad smell, or looks milky, clear sign of water/coolant in oil.

Also, what does your exhaust look like?

If oil looks ok, you can have your oil lab tested. I have never done it before, but have been told it is like a blood test. They will tell you of any engine issues.

 

[chevync]

I just replaced both heads due to the castech problem, both were cracked and both passed a pressure test when the engine was cold, once warmed up they wouldn't hold pressure. Do the pressure test and make sure they aren't leaking. Mine didn't show any signs of oil/water in the oil other than the oil fill tube and cap. This is after less than 3k miles on a newly rebuilt engine, last time I checked the oil it showed signs of leakage in the oil. I replaced mine with a set of 862 heads.

 

[opiefavors]

That looks excessive to me. Not your typical moisture under the cap. I'd do the testing the previous posters suggested.

 

[rybern]

Wow, this turned around pretty quick. Ill check the head number tomorrow. The oil was black but definitely not milky. I also didn't notice anything unusual about it. I have a compression tester but have never checked anything with coil packs. I won't have time to mess with it until Sunday. Btw, the Tahoe isn't my daily driver so I don't really have to drive it.

I like the idea of sending the oil off. I guess google is my friend here.

I have an appointment at the stealer to get my seat module reprogrammed, but I might put it off due to the possibility of severe engine damage.

I'll keep you guys posted.

 

[rybern]

I have confirmed that at least the passenger side head is marked 862.

 

[chevync]

I have confirmed that at least the passenger side head is marked 862.

Castech heads came in 706 and 862, but more in the 706. Never hurts to check them though. If it's not a head problem I would at least pick up a catch can, that will help with the build up.

 

[undy]

Don't ingest it but a simple "taste" of the froth will tell if it contains glycol. If it does then it's not condensation and time to pull the engine apart. I've used this method numerous times.

 

[rybern]

Don't ingest it but a simple "taste" of the froth will tell if it contains glycol. If it does then it's not condensation and time to pull the engine apart. I've used this method numerous times.

Hmmm, I don't know what glycol tastes like. Should I use some anti-freeze as a sample?

I've contacted Blackstone Lab for a free test kit. Samples are $25, seems fair enough to me.

 

[undy]

It has a sweet taste to it. That's why it's such a danger to pets. Blackstone will pick it up too. I just like to save $25 and find out now.

 

[OR VietVet]

If you can get to a shop with a gas analyzer then have them check with a cold engine start up and as it warms up. By check I mean have the rad cap off and use the sniffer at the rad neck and check for hydro-carbons. If they are there then that is a sure sign of head/gasket problems. The pic looks excessive. I have seen just a small amount of the white milky foam just under the fill cap but what I see in that pic definitely looks like more than just the short trip/cold start condensation problem. I am leaning toward the heads problem but the gas analyzer should help narrow it down.