Need to check timing chain or belt on a 4.0?

I've got a '96 XJ w/ 4.0 and I've had it from miles 88k through 177k (now). Far as I know the timing belt/chain has never been looked at. Should I be concerned with changing it out or any kind of maintenance with it?

Well there's nothing to maintain but the tensioner and if you've gone that far I would just replace the timing chain then. Otherwise I wouldn't worry about it unless your seeing something like timing fluctuation!

Nope no need unless you're in there that far and are well over the 200k mark

We pulled the motor in my 96 at 400,000 miles.Using a Snap-On Brick scanner before the pull,the sync between the came and crank signal was still "0".
Timing chain would be least of my worries.

These aren't Japanese motors with overhead cams driven by stretchy rubber bands.

These are old tractor motors.

They may not wind up to 10,000 RPM, but they behave themselves well long term.

Good to know I don't have to worry. Thanks for the info everybody.

When I pulled 4.0 ho timing chains with close to 200 thousand miles it was not stretched enough I though it had to be replaced, still did since it was apart and I had the new parts already.
Most 4.0 guys tend to report the timing chain still looks good on high mile engines, however I have read of other 4.0 owners with a lot of chain stretch after just over 100 thousand miles. Not sure if there is a change in the design at some point or why they'd see excessive wear when others don't.

I would not worry about it unless you have a problem.


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I had a 96 with the 4.0. The motor had 280k on the clock and we never opened it before the swap. She ran another 300k roughly until it had nasty popping and backfiring from the tail pipe. I thought the cracked manifold had finally burnt a valve. Nope. After over half a million miles, the chain had stretched far enough to hold the exhaust valve open longer than anticipated. The only noise you herd from that motor was exauest leak and lifter clatter. Went over 175k on 3 dead lifters. A month after a new timing set, cam and lifters, some b**** rearends it in the driveway hard enough to rip the shocks out of there mounts. Sold it to some high schooler who loved to hit rev limiter. Well one time the almost 600k bottom end didn't wanna take it. Chucked a rod and tried to saw itself in half.


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my 87 has 290,000 miles on it, and the timing chain seems too be the last of my worries. Three 87-89 rigs over 250,000 miles with out TC issues. My 2001 Saturn (also has a real steal timing chain) has 273,000 now on the chain.

Maintenance? Keep plenty of oil in the engine, LOL

Interesting. But how do you know the dizzy has not moved and compensated for TC slop? I just replaced my Dizzy after the helical gear sheer pin finally failed. It was a rebuilt (12 years ago) dizzy.

Second question can the MT-2500 run that test on the Renix? Does it even show the Cam signal on renix? I have one I use, but do not recall seeing that test?

Wayne Sihler said:

We pulled the motor in my 96 at 400,000 miles.Using a Snap-On Brick scanner before the pull,the sync between the came and crank signal was still "0".
Timing chain would be least of my worries.

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