I just bought a 01 Xj. The PO said he thought the head had gone. It runs but is REALLY Rough I haven't driven it other than pulling up on the trailer. I have never rebuilt a motor or anything before and don't have much knowledge on this. I took it to a show and they did confirm the head was gone. They say I need to purchase a new motor and gave me some quotes from Jasper, ATK, and 1 other Company. The owner offering all the parts at their cost just to keep his guys working labor just to keep there guys working all said and done was 3700 for the Jasper installed and the other two companies where about the same around 3000 out the door for the motor installed. I asked him if it needed a new engine or can we just replace the head and he said no the motor was shot. He showed me the Compression numbers from 1 to 6 - 110,100,90, 100, 100, 110. I don't mind buying a new motor if it needs one and I know he's giving me their cost because he called and got the quotes with me in the office on speakerphone so I hear the numbers. I just don't want to spend 3000 if I can get a new head and have it running for around a $1000. I don't think the guy is trying to rip me off but I just wanted to see what you guys think? I know its thought to diagnose something over the internet.

 

How did they confirm the head was "gone"? Antifreeze in the oil? Oil in the antifreeze? Y-ray vision?

What do you mean he showed you the numbers? Did you watch them do the test? If not, I'd check the compression myself. Get the loaner tool from Autozone.

Is it a 0331 head?

 

BTW how many miles on the 2001? And check the serial number to make sure it's a 2001.

 

Yes its 0331 Head and yes there was oil in the antifreeze and when I check the oil on the dipstick it was brown and milky. I didn't watch the test compression test but he did offer to show me. I'm going back tomorrow he's going to put it up on the lift so I can look at the undercarriage for rust so I can ask him to show me. It looks totally rust free from everything I can see. I just wanted to get a better look before I decide to dump a few grand into a motor.
I've used the shop for other things for years and everyone in my town uses (really small town) him so he seems pretty trustworthy from what I've ever dealt with him on. I guess before I give him 3000 I just was trying to make sure my ducks are in a row since I really dont know much about motors.

 

112K miles its a 2001 according to the title but ill run the vin just to double-check

 

IIWM I'd get a used engine.

4.0s never ever ever ever ever ever ever ever ever ever ever go bad.

OK sometimes.

 

Serial number of the ENGINE to see if it's original.

112,000? I'd look closely at flushing the engine out and reusing it.

I mean, 112,000 is like new.

 

Thanks, Ill check the number and make sure it the orig. motor. He was saying the Compression numbers were really low so it needs a rebuild or swap in another motor. He said he could find a used motor from a junkyard or we can order a remanufactured one from a company. I'd rather not do a junkyard motor and have to replace it again in a year.

 

Have you changed the oil and run the engine ? and if you have what was the oil pressure at ruuing temp.? you can get a used head from a 2003 or 2004 grand cherokee they have the 0331 tupy head that doesn't crack like the 2002 and earlyer head does .

 

You are far better off finding a local rebuilder than buying a crate engine. Ask at your local NAPA. They usually know who's good.

 

No when I bought it the P.O. said he thought the head went bad. When I started it to pull on the trailer it ran really rough and so I didn't want to hurt it more if it only needed a head. I trailered it right to the shop. I asked them to look at it and they said there was antifreeze in the oil. Which I did know before I took it there. He first thought he could just do the head but then said he ran the compression test and it was too low and he said it needed to be rebuilt or he could swap it out with a remanufactured engine or a used one.

 

I just dont know enough about engines to know what I'm looking for. My uncle was my mechanic and did all my engine work. Unfortunately, he passed away 2 years from cancer but he did like the guy where I took the jeep too. They were not really "friends" so to speak but they both owned shops near each other and my uncle never had anything bad to say about the guy and often said he did good work. They would talk whenever they would run into each other out and about (again small town) I've done some searching for Compression #s and it looks like 100 is low but I really have no idea lol.

 

I would check to see if the head is cracked they all crack it the same place and it is right under the oil cap if you get it warm to see if the coolant is leaking there , it will put coolant in the oil . then the coolant will hurt the engine bearing and give you low oil pressure .

 

120-150 PSI maximum variation 30 PSI.

Again, I'd test it myself with a known good compression tester. I'm just not seeing a 4.0 engine with 112,000 miles and compression that low already.

 

BTW you got any engine codes on that thing?