Hey all... I've been in and out of my 4.0 several times over the last 6 years of owning it and have viewed this site a lot as a guest. However today I'm stumped by my XJ.

First - some light colored foam/sludge on the dipstick when checking the oil before going to see the family. Now I know this can be a vacuum line issue, however they are all new within the last 6 months. Any other thoughts here? PCV valves maybe? Secondly there was some moisture/condensation on the dipstick as well, however I think this might just be due to the extreme cold the last few days (below 15 daytime and well below zero at night) update - pcv valves good, vacuum lines all checked. fearing head gasket

Lastly - the one that I really have no idea on is a 'zinging' sound from the engine bay through the rpm range and occasionally once up to speed. I'm talking like the sound of have a hoard of red eyed cicadas under the hood. It's not heating up so I don't think it's the water pump, doesn't squeal or groan when turning so I don't think it's the power steering pump either. Alternator seems fine as well, no variation in the voltmeter. Still runs great, 50ish oil pressure going down the road and running strong.

Any suggestions would be great and Merry Christmas to everyone!!

 

Probably a good idea to just start with a wet/dry compression test. I could ask how meny miles, how is the oil it's-self, is there foam under the oil cap. No matter what the answers are to those questions, if there is foam on the dipstick a compression test is still a good idea.

Don't forget, just like you see in "cracked 0331" threads, coolant in the oil can eat engine bearings. (you don't have an 0331 head).

Do you drive it regularly, (up to temp), or does it sit allot?

 

Flint... I drive it on a regular basis, it's a daily driver. Trying to find somewhere to get it in today for a compression test, while building my wishlist on summit racing for a replacement engine if I get the worse case news. I know I don't need to jump to that, but it's a used block as it is. I pulled it out of a wrecked 95 about 75k miles ago with no clue how many miles the wrecked Jeep has on it.

My lady is rolling her eyes, she knows I'm only seeing this as a reason to snag a mopar 4.7l. haha.