gunk in oil filler cap

[JimW1999]

I've noticed some gunk on the filler tube and cap when I do an oil change. Looks like water in the oil but I'm not loosing any coolant and the oil seems fine and dandy when I drain it. Could this just be condensation in the filler tube? I've read of the cracked heads and hope that's not the case, I'd think there would be some coolant loss if it's leaking into the oil - unless the oil leaks into the coolant as well????

2000 JGC 4.7L

[bringselpup]

You would definately have coolant loss. But don't just go by the level in the overflow reservoir. Because a problem like yours would mean the system wasn't sealed and as the engine cooled it wouldn't have a vacuum seal to draw in the coolant from the overflow tank. Pop the radiator cap when cool and make sure you haven't lost coolant level there.

But if this is over several oil changes, and you're not losing coolant it probably is some kind of condensation.

Is it a DD with a short commute maybe?

[JimW1999]

Thanks that's somewhat reassuring.

Is it a DD with a short commute maybe?

Not sure what the DD stands for?

[Bob D.]

Originally Posted by JimW1999

Not sure what the DD stands for?

"Daily Driver"
You can pressure test the radiator for leaks, but it's most likely just condensation.
Chrysler has addressed this in earlier 4.7L motors with redesigned parts that prevent the build up:
Part # 53032126AA - Baffle, Oil Fill Housing
Part # 53032389AC - Cap, Oil Fill Housing

An oil change or a switch to a different brand oil may also help.

[JimW1999]

Thanks for the info on the Jeep and decoding the DD for me. I'll look into the parts you mentioned and give it a compression test, seems to be running fine and it's good to know there's a known issue with condensation.

FWIW - I am the DD and it's a 30 mile commute 25 miles on the highway smooth sailing @75mph.

[fredjacksonsan]

What kind of oil are you using? I had a couple vehicles that got a waxy substance on the bottom side of the filler cap when using Quaker State several years ago. Try changing brands of oil (or even going synthetic) and see if the problem clears up.

[JimW1999]

Castrol GTX 5W-30. 6 Quarts in my 4.7L
Is there anything special required when changing over to synthetic or just the same old drain it, changed the filter, add new oil?

[fredjacksonsan]

If you're under about 60K miles, I would just change it as normal.