Bad Lifter or Something Worse?

This thread is about a friend's 2000 XJ, 2WD 4.0L AW-4. He bought it with 78K in Sept '09 and, while a bit neglected, everything seemed to function ok. First off it looses about 1 qt coolant/week (200 miles of driving). I discovered this when he brought it over and it was 1.5 gal low on coolant!! I'm guessing that's a small crack in the head (0331 casting on a 2000, correct?).
Anyway he called this weekend and it started making a thud/thunk noise when cold. It goes away when the engine gets hot enough and, once warmed up seems to run fine. Since the oil hasn't been changed since Sept '09 I'm guessing he managed to plug up a lifter, espec if there's some coolant residue in the oil. The oil itself is filthy but not chocolate milkshake indicative of a cracked head/blown head gasket. It sounds like a bad lifter to me...any thoughts???

The sound could be coolant that has pooled in a cylinder. If so, it won't take much more of it.

When it has sat overnight and is cold, pull all the plugs then crank the engine and see if one of the cylinders tries to "spit in your eye".

Check the oil fill cap inside for the milky residue from the cracked head. Bad lifter just clatters, not thud/thunk.

Underside of the oil filler cap looks ok. Good call on spitting coolant through the plug holes. #3 & 4 would be most likely to do this, correct?

I have read that # 3&4 cyl's are affected the most. But try them all 1 at a time, and do a cold and hot compression test while your at it.

JumpinXJ said:

I have read that # 3&4 cyl's are affected the most. But try them all 1 at a time, and do a cold and hot compression test while your at it.

Click to expand...

Yes, 3/4 are most suspect.