Originally Posted by JKlad

Obviously there's been dozens of threads & hundreds of posts her regarding the propensity of a good number of these 3.8L V6 motors to consume large quantities of oil, often leading to dry sumps & spun bearings, and a lot of conjecture as to the root cause; rings installed incorrectly, incorrectly assembled cranks, bad drain-back valves in oil filters causing dry starts, the specified low-viscocity 5W20 oil not being up to the job with loss of film strength resulting in damaged bearing surfaces, etc.

There was a discussion about this on one of the local forums where I am & one of the members, who is a mechanic at one of the Chrysler/Jeep/Dodge dealerships here, chimed in about something I had not heard before. Apparently there was a known quantity of motors produced in '07 & early '08 that, due to a fault in the manufacturing processes at the engine plant, resulted in the blocks being bored & honed incorrectly resulting in one or more cylinders in the block being noticably out-of-round.

He stressed that the fault was limited to a small number of production runs and the number of motors affected would be statistically small compared to the total quantity of these blocks produced, however he has personally seen two of them go through his shop since the JK was introduced here 4 years ago. The symptoms of these motors sounded all too familiar; higher than normal oil consumption from new, gradually getting worse and then suddenly without warning increasing at a geometric rate, resulting in dry sumps from full within a short period of time, leading to oil pump starvation and spun bearings. Apparantly the out-of-round cylinders cause the oil expander rings to become clogged and siezed and the compression rings to wear quickly & unevenly and to usually lose tension & fail at around, wait for it, 50-60K km or 31-37K miles which is the familiar mileage for the infamous "40K mile spun bearing club".

Apparantly the instruction to dealers here from Chrysler is that if the cylinders are found to be out of round when the motors are torn down to investigate high oil consumption then they are to quickly and quietly replace the short block (or entire motor if required) without question (free of charge if the motor is still under warranty, otherwise a small contribution of like $500-$1000 from the customer is requested) and the faulty block & components are to be shipped off to Chrysler without fail. So without trying to sound like a conspiracy theorist, it appears that Chrysler knows that there is a problem and is trying to deal with it as quietly as possible to avoid the spectre of recalls and class actions.

So, any other Jeep mechanics out there have similar experience with finding some of these oil burners to have cylinders out-of-round? It would go a long way to explaining an issue that has affected some members here first hand and had others (like myself) paranoid about premature motor failure and going into a panic every time they hear (or think they hear) a new tick or rattle coming from under the hood.

Originally Posted by ronjenx

ProjectJK08,

That is a FANTASTIC story! I'll bet it's the only one like it on the forum.

Originally Posted by Rottweiler Hauler

Found out yesterday, engine is toast! Head is warped, valves won't hold compression, 2 cylinders are all carboned up, compression rings are in bad shape on cylinder 5 with the oil control ring gone! Well, it was in pieces in the oil pan...

They are waiting for the paperwork from the warranty company to show up on Monday to place the order for the new engine. It's been in for 16 days and they hope to be done by this next Friday.

Originally Posted by Rottweiler Hauler

Previous post:

My 09 X with 37k miles,is in the shop right now. Started off with the ticking noise on startup. Oil consumption test showed 1.7 quarts gone in 1000 miles. They started teardown yesterday and found three of the cylinders with heavy carbon and one piston "loose" in the bore! Waiting for inspector to look at it today...