Hey everyone!

I haven't posted on here in a while! I have a 2001 Cherokee Limited with 172k miles on it, rebuilt engine with 70k on it, and have been driving without any issues for the last two years. Now I think I have my first major issue! Earlier this month she started running a bit rough at idle, just sputtering here and there, and when I'd hit the gas she'd go a bit back before going forward and then it would run normally. This went on for a bit, then when I was getting off the highway last week, on the exit ramp and slowing down, my CEL came on and started blinking (from what I've read on here that indicates a cat damaging misfire) so I get home and read the code. It's P0305, misfire on 5. So, I hopped on here did some research and started to go through the steps. I Seafoamed the intake and my gas tank. My plugs were kind of getting old so I replaced those, she is still running rough, still occasionally blinking CEL. The injectors are relatively new, put in last year, and the fuel pressure is good at the valve on the fuel rail. So I decided that, since I don't have the skills or the time to get into an internal issue, I brought it to the shop to have them take a look at it. They did a compression test and came up with this (the guy on the phone didn't give me specific numbers just the ballpark for each one)
#1: 170s
#2: 120s
#3: 160s
#4: 160s
#5: 160s
#6: 160s

He then went on to tell me that they can either clean out #2 and basically run chemicals similar to Seafoam through it to see if it's just sludge keeping the valve open. Or they can take the head off of it and send it out for a valve job.

My questions:

- Why would the misfire show on #5 but the compression be low on #2?
- Are these numbers really high and a cause for concern? I have seen the range as 120-150
- Are valve jobs pretty common with xjs? When I bought this the engine was rebuilt with 40k on it so this just seems premature
- What is a fair price for this kind of job? I was quote at $1350 and that seems so high. He also told me I was already $400 in the hole for the compression test, leakdown test, removing the valve cover, and looking at the brakes (unrelated issue).

I'm curious what you guys would suggest I do? Do I have them pull the head and do the valve job and hope that catches the problem? Or do I sink $120 more into this and have them try to clean everything out?

 

you have a dilemna as 120psi on a cylinder with others 160s is too much variation to be acceptable

personally I would be concerned about piston or rings, ( did they check if the pressure comes up slightly with oil added to cylinder), as I have found in the past bad valves give very low readings

hard to see any way around taking the head off, and yes, I would be concerned about my wallet

 

The valves can usually be visually inspected with a borescope camera (cheap these days on amazon - I got one with a 20ft usb cable and built in lighting for $25 - and works with any android phone). This can help determine if valves aren't seating correctly without removing the head and can also spot any mechanical damage to the valves (missing chunks, etc). It can also show if there truly is a lot of carbon build up in the area. Shops usually have one - you might want to ask them if they could visually inspect the #2 valves with it. If not, you could shop around to get a second opinion on both the compression test while also asking if they can visually inspect the valves without removing the head.

 

Hey guys, thank you for the advice thus far. After doing some more googling and searching on here I realized that I really didn't have a choice, and since I was already $500 in the hole, I decided to have my shop pull the head on the jeep.

The bad news:

Heard from them that the head (which is a TUPY remanufactured head) is so badly machined that the exhaust valve on #2 was actually stuck in place, and most of the valves do not sit properly and some of the holes don't line up correctly... and that led to all the problems I've been having recently. Curious about your thoughts on this. The shop is telling me the machine guys are saying to put a brand new head on there, but that I'll be looking at a new total of over $1700 for the head job with the same valves, springs, etc. from the old head.

How could this have happened so suddenly? Wouldn't the jeep run rough more consistently? When it's under load on the highway I have no problems with it. Any advice would be greatly appreciated! My total cost for all of the stuff going into this as of now would be $3200 with the new head. The shop will have it for so long that I just had them replace the diff oil, and they had a few other issues that they are fixing as well including the rear brakes. I'm mostly focused on the head/valve issue though. Again, any feedback on this? The frame is in such good condition and the bottom of the engine is solid. Also curious what is the best head for a 2001? I don't want to end up with a 0331 and have it crack in 2 or 4 years.

 

Hello again all!

For those of you that are still following this or are running into similar problems, I started a new thread here: https://www.cherokeeforum.com/f2/mul...ciated-254368/

I'm still learning how to work this whole thread and forum thing so if I am breaking any rules I'm sorry!