Kris smith

Newb here going to look at a 1998 xj guy says it just started knocking after sitting 2 weeks. Says it is only knocking at idle. Speed hot or cold I'd imagine besides catisrophic failure and flex plate or harmonic balancer what could it be and what is he most likely cause ? Talked to a jeep tech said something about piston knock he had one that blew the piston out of the bottom o the pan h said a super rare case any help please guys I did search but nothing matching the same problem

Kris smith

Any one

zkeifer

Low oil, bearings, piston split in half could be alot of different things. Have seen motors shoot the rod right out the pan, put giant holes in the cylinders, split the piston in half, disintergrate the piston to tiney pieces.

Kris smith

Jeez so I guess I should stay away. What do junk yard 4liters go for on average ? I really want a Cherokee This one seems nice execpt the knock I havent heard yet

Kris smith

And z keifer thank you so much for you reply to a stupid newb and not being a jerk like some other forums.

Firestorm500

Offer the guy $500 for the Jeep and a clear title. Figure on spending $2500-3500 for a rebuilt engine.

Kris smith

Ok sounds good I could do that

GrimmJeeper

i'd not worry about it. 90% of the time a knock only at idle is the flex plate being cracked. rod knocks don't go away when the RPMs go up, they get much louder. lowball him and buy it, pull the trans and change out the flex plate.

don't tell the seller that though

could also be a stuck lifter from sitting, a bottle of marvel mystery oil in the crankcase will likely fix that problem.

Firestorm500

"...a bottle of marvel mystery oil... will likely fix that problem"

1. Start engine.

2. Run at high RPM while a helper holds a large sack full of money in front of the air intake.

3. Let the Jeep ingest all the money.

4. That will likely fix the problem.

Kris smith

Sarcasm nice I am trading one of my cars for it possibly