CrawlOver

Hi all, I just got the dreaded p0304 code and took it in to find out that the valve guides may be the culprit for lost compression during a ride on the #4 cylinder. Estimate is ~$5,000. It's a 2012 JKU.. what are some good options here? an engine swap would be way too pricey.. i was thinking of an engine rebuild? but what would that cost and would it help the performance at all?? thanks for your thoughts.

JFish'n

Didn't the 2012 have a known issue related to the cylinder heads or valve seats or something like that?
IIRC the fix is a new cylinder head.

CrawlOver

It seems so from what ive read on the forums but i called fca and they said my vin doesnt show it as qualifying.
what would be a beefier engine that is as direct fit as possible?

Sixty4x4

Valve guides being worn will not reduce compression as they are on the opposite side of the valve head from the combustion chamber. Lost compression is a result of faulty/broken compression rings, excessive bore wear, hole in the piston or a burnt exhaust valve. To check the rings for loss of compression remove the spark plug on a warm (not hot) engine and squirt some engine oil in there and repeat the compression test. If it comes up likely culprit is the rings. But seeing as it is only on #4 then I would also suspect broken compression ring(s). Biggest telltale of worn valve guides/seals is that puff of smoke when reaccelerating after a long compression slowdown with foot off the throttle. Engine swaps are really limited to other V6's (waste of time) or Chrysler V8 Hemi (really complicated and expensive). Chev V8's are popular but also fit in the expensive category. I believe you are stuck with a rebuild and if the damage is confined to one cylinder then it can be done with the engine in the Jeep and one cylinder head and oil pan removed. Tedious but less labour as you can dismantle some yourself and hopefully find a good mechanic who will come to you. If it is a daily driver then you are in a dead end for options. Sorry cannot help anymore.