Timing chain on the outs?

Could some kind soul give me an idea of what a timing chain sounds like when it's about to give up the ghost. For a few months now I've been hearing this metallic scraping noise when I accelerate from a dead stop. At first I thought it may have been my mechanical fan touching the shroud because the new aftermarket fan clutch does seem to be a tad taller than OEM. I pulled the shroud and still get the noise.

Not sure if this is related but sometimes when I start it there is a loud thunking noise from the front of the engine and then nothing. Usually starts up on the second attempt though...except tonight. It has finally pooped out. I got the loud thunking noise but now it won't start at all.

Will a broken timing chain cause a no start?

Here's a quick check - take off the distributor cap, turn the main pully (use a 3/4" socket and breaker bar) and watch the rotor. Turn the crank at least 1/2-turn both ways, and make sure the rotor moves almost immediately. If it doesn't, chain stretch is certain.

How many miles? It's not uncommon for the 4.0 to do a quarter million or better on a chain - I've got 236Kmiles on my 88 with nearly no noticeable stretch (not enough to make me want to change the chain) and my 89 is running about 185Kmiles with the same condition - nearly none. You'd have to work pretty hard to stretch that chain in anything less than 300K or so, I'd guess.

Try turning the crank while watching the rotor and see what you get. If you have more than 15* or so turn at the crank pully before you see the rotor move, change the chain (and the front main, you've got it torn to bits anyhow. Probably the water pump as well, since you've got it taken apart anyhow...)

I give you such a high figure simply because the timing chain and camshaft don't do much for ignition beyond spin the rotor - I've turned the distributor 180* with the engine running with no noticeable effect (not even a stumble...) However, it WILL effect the timing of valvetrain events, and that is a problem. Also, if the chain has broken or slipped, the distributor won't turn, and that is also a problem...

5-90

Thanks for the heads up. I will check what you mentioned tomorrow morning.

I am the second owner of this XJ. This is a new rebuilt engine (from Checker Auto) I had a friend put in a couple years ago. The previous owner ran the old engine to death literally. He neglected the **** out of this poor Jeep. I guess he liked having an "inline 5"!

That thunking noise at startup kind of concerns me. If a timing chain is loose and skips a tooth will it cause a reaction with that drastic of a noise?

XJade said:

That thunking noise at startup kind of concerns me. If a timing chain is loose and skips a tooth will it cause a reaction with that drastic of a noise?

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Yes. It seems that your timing chain was stretched and causing the noise, but later jumped a tooth or two and threw off the valve timing (and distributor timing) causing the no start.
Just hope that the valve timing didn't get thrown off so much that the pistons hit the valves. If the engine runs like crap after you've installed a new chain & tensioner, you might wanna do a compression check to make sure you don't have bent valves.

Good morning everyone. Thank you for your responses. Looks like I'm looking at a timing chain job. My first! Ah well. What can you do? Gotta be done. I'm waiting for the sun to come up so I can verify that it is the chain.

I've been comparing prices and surprisingly, it looks like the dealership may have the cheapest parts. Questions:

1) Besides oil seal should I also change out both sprockets? Anything else while I'm in there? Should I get a new damper/pulley?
2) Is the tensioner also called a "bumper"? I see that in the parts diagram but nothing called a tensioner.

You sohould be able to get the timing chain as part of a "set" - chain and both sprockets. That's how I always get it, so I think it slipped my mind.

If you were changing the chain fairly early, you wouldn't worry too much about the "bumper." However, if it's a bad as it sounds from your posts, get the bumper anyhow and do it all. I think the one from the AMC2.46 will work, and the one from the 258 may as well (if you have the old part out already, take it with you. Oddly, one of the others may be on the shelf while the 4.0 part isn't for some reason...)

Expect this one to take an afternoon, and you may as well do your hoses and belt while you're at is, since you'll be taking them down anyhow to get to the timing chain. Whenever you dig in for major surgery, it's usually a good idea to tackle any "maintenance items" that are between you and the main job...

5-90

The 4.0L and the 2.5L can share the same timing chain and sprockets, but the 2.5L uses a tensioner and the 4.0L does not.

This past month I replaced, in my '89 XJ I-6, the fuel injectors; waterpump, thermostat; harmonic balancer aka dampener; all heating/cooling hoses and last but not least the timing chain and gears.

First a big thanks to all the members at - I couldn't haven't done it without you guys! That's no lie! You guys saved me a few thousand in labor and double markup in parts.

Yes change the harmonic balancer with the timing chain and gears. My balancer had the rubber not only coming out the front but after I pulled it off I noticed rubber was coming out the back and was making a groove into the timing change cover...I caught it in time for sure.

I purchased the waterpump, timing set and harmonic balancer all at NAPA - all were about $50.00 each. The dealer wanted about twice the price for everything. And the dealer only had refurbed water pumps...NAPA's are new with lifetime warranty.

Regarding the harmonic balancer (hb). To loosen the bolt use a 3/4 inch socket with a breaker bar jammed underneath the passenger side frame. Goose the ignition for a millisecond...the bolt will be loose.

Use only a hb puller only - a gear or wheel puller will pull off the outer ring of the hp. A hb puller costs about $13.00.

My timing chain had 5/8 inch play - the max should be 1/2 inch.

For your book 5-90:
A new timing chain installed has 1/4 inch play. I would say if you can measure your timing chain and it has 1/2 inch play you might as well change it, as the hard part is over!

Installing harmonic balancer was the tricky part as the book mentions "Just tap it on" or something like that. Fo-get-it! Never happen in a million years! I used a wide fender washer with the original bolt to slowly move the balancer on to the shaft. The stock washer is too thick.

My '89 XJ has over 190,000 miles on it. And I will say installing new fuel injectors and a new timing chain set has really brought the XJ back to life. Smooth, smooth acceleration, it's more responsive and has more power for sure.

Thanks to all again!

John V.

Hey guys. Just wanted to post an update. I've spent about two days on this epic task. Oh joy. Of course it doesn't help that I'm doing it during a work week and have to put up the tools in order to get some sleep.
It went like this: wrench, give up in frustration, wrench, take a nap, wrench, give up in frustration, wrench...

And I am only half way done. Everything is off. Tomorrow I piece everything back together again.

All in all it went well. A good learning experience for this beginner. Trying to get that damn harmonic balancer off was a PAIN and that took up most of my time. I've decided to replace it. The rubber looks a little sketchy.

Finally got to look inside the timing case today. The chain had about 3/4 inch of slack. Not good I assume.

I'm putting in all OEM parts. It cost me $50 for a timing set and the gaskets and seal. Not bad.

Question: Should I do away with the oil slinger seeing as I'm putting in a dealer harmonic balancer? I read the thread about a superceded part. Is the slinger vital to the function in that timing case?

Congrats...yeah it takes more than an afternoon...don't know what 5-90 was thinking! *-} it's a lot of work.

I can't answer the oil slinger part as I purchased my harmonic balancer from Napa and it looked just like the stock timing chain and gears. So I kept the slinger in.

What problems did you have pulling of the harmonic balancer? Did you use a harmonic balancer puller? That's the key and the breaker bar trick in my above post.

The most play in the chain should be 1/2 inch...it's time to change yours. Mine had 5/8 inch play.

Before you put on the timing chain cover make sure the shaft for the harmonic balancer has the key facing up for easy alignment...I learned the hard way!

Also install the bottom oil pan bolts first to get the cover alignment going - I did the front bolts first then tried to do the bottoms but the rubber gasket moved to block the bolt holes. Had to take out all the bolts and start again - twice!

The book says to install the timing chain cover with the old front seal for alignment, then pull it out and install a new one. But I just installed a new one while on the bench as there really is nothing to align since the harmonic balancer needs to be in anyway. I used a galvanized pipe joint - with 2 inch diameter to seat the new seal. Don't know if that was the proper thing to do...but it's not leaking...maybe 5-90 will give me hell!

Johnny V said:

What problems did you have pulling of the harmonic balancer? Did you use a harmonic balancer puller? That's the key and the breaker bar trick in my above post.

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Thanks for the suggestions. It's friggin' raining out. Gotta wait out the rain to piece it back together.

I did use a puller. But I used it improperly the first day. I bought the puller ages ago. And so I forgot there was a pointy metal cup that goes on the end of that large center turnscrew. Once I found that and put it on the puller I was able to torque it properly. Thank goodness I didn't strip out that crankshaft bolt hole in the process. That pointy cup is wider than the end of the turnscrew for a reason! To keep idiots like me from "screwing" things up.