Hi Folks, what is the recommended mileage to replace the timing chain and tensioner? I just bought my 96 Classic 4.0 automatic, with 153,000 miles. It runs perfect, and these engines are well known to last, but I want to keep it running great as well.
My 90 XJ just passed 230K, the chain has never been replaced. I'm replacing the failing harmonic balancer on the 88 MJ and will be assessing the look of that one at 170K. I should probably do the same to the XJ but...no symptoms...so, if it ain't broke...etc.
Just be happy it's a chain and not a belt. Just keep it well lubricated.
1990 XJ Laredo - White & Chrome
1988 MJ Pioneer - Metallic Green and Black
i say that if your engine begins to feel a little under powered but runs fine then why not do it as preventative maintenance? if any of you with higher mileage engines take your oil pan off, you can check the slack in the chain and ill bet youre surprised. about 30k ago i probably had at least 1/2" of slop. i plan on changing mine at 200k just for good measure. i would rather it not break while im driving, or to have it become stretched enough to make my engine run noticeably poorer.
I was considering doing this, because I've replaced alot of stuff on the motor tune up wise, and the entire suspension ect.
However as a mechanic and an avid car buyer, when I see new timing chain, I normally think it must have snapped, because its not something most people do. Timing belts are common to be changed on hondas, thats about it.
IDK how I feel about this, just weird that everytime I start thinking about something to do to the jeep, a thread pops up about it within 24 hrs.
Thats because of the low tolerances. if the valve clearance was like that on some of the newer 4's and 6's... bam! Toast!
Its not close tolerance it is out right interference. The i6 won't contact a valve even at full lift I'd your break the chain. You have to break a valve spring or retainer for contact to happen.
An interference motor doesn't have that kind of open combustion chamber.
'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.
If you DO feel like replacing the timing set, make sure you call around first and verify that local stores have it. I was in the middle of my balancer/front cover problem a few weeks ago and NOBODY in town had a timing set for the 4.0. Out of at least 10 parts stores, it was a "special order" item.
I have 250K on my 92 and the chain is extremely loose. I just said screw it and put it together without a new set. Still runs fine.