FSM mistake?

A question for anyone who may know, a heads up for anyone who doesn't know.

I replaced everything behind the timing case. Crank pulley, sprockets, chain, oil seal.

According to the FSM I was supposed to line up the timing marks before removal. Did that, but than after new one installed I was supposed to turn until they were in certain positions, did that. Than it says there should be 15 pins between the marks, nope. Also says there should be 48 links on the chain, nope, 64 (old and new)

Anyway I put it together once, 15 pins between... ya, that was wrong.

Did it again, timing marks lined up, fired right up.

Other than the fact the FSM has 2 different directions, which is actually correct? Other than the fact lining them up was the only option that worked for me.

Anyway, the FSM is rather confusing, so if anyone is thinking of doing this job, and using the FSM to do it... keep them lined up. I have no idea what the purpose of the 15 pin count was, but it did nothing but waste my time, piss me off, and nearly make me miss the butchers before the big fight night tonight.

beakie said:

A question for anyone who may know, a heads up for anyone who doesn't know.

I replaced everything behind the timing case. Crank pulley, sprockets, chain, oil seal.

According to the FSM I was supposed to line up the timing marks before removal. Did that, but than after new one installed I was supposed to turn until they were in certain positions, did that. Than it says there should be 15 pins between the marks, nope. Also says there should be 48 links on the chain, nope, 64 (old and new)

Anyway I put it together once, 15 pins between... ya, that was wrong.

Did it again, timing marks lined up, fired right up.

Other than the fact the FSM has 2 different directions, which is actually correct? Other than the fact lining them up was the only option that worked for me.

Anyway, the FSM is rather confusing, so if anyone is thinking of doing this job, and using the FSM to do it... keep them lined up. I have no idea what the purpose of the 15 pin count was, but it did nothing but waste my time, piss me off, and nearly make me miss the butchers before the big fight night tonight.

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I know the earlier years (87-94 i think) used a 48 link chain. The later years use a 64 "silent" type chain.. that is actually stronger then the earlier.
IIRC the 15 pin thing was only used for the 48 link chain.
By chance were you reading from an FSM that was from another year than yours?

Did they change the chain design due to excess noise?I ask this because my 89 has alot of timing chain noise and I have replaced the timing set because of that and it is still noisey.

Muad'Dib said:

I know the earlier years (87-94 i think) used a 48 link chain. The later years use a 64 "silent" type chain.. that is actually stronger then the earlier.
IIRC the 15 pin thing was only used for the 48 link chain.
By chance were you reading from an FSM that was from another year than yours?

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This was all straight from my 1997 Jeep Cherokee FSM.
Could have just been something they never thought of changing, or forgot too.

Either way, its done now, but wanted to bring it out for anyone in the future.

If you're not changing the timing chain, you don't need to line up the marks (and it's obviously been working fine.)

No matter the engine, I've lined up the marks to remove, installed the new set, and then turned an even and rechecked the timing marks. Realigned? Alles gut - button it up and finish the job.

You can count links, but the real test is if the timing marks come back into alignment when they're supposed to (every alternator crankshaft turn.) If that works, then you're fine - and it covers various revisions and updates. The camshaft must turn only once for every two revolutions of the crankshaft - if it doesn't, you've got bigger problems than an updated timing set...

So is the newer and older set interchangeable if you change out gears and chain? Will they fit inside the same cover?
Questions are just academic as I don't plan to make the switch but thought someone who minded the timing chain noise might want to go silent. 5-90 do you know?

5-90 said:

(every alternator crankshaft turn.)

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alternator or alternate??? Just playin' with ya-- we know what you meant:conceited

It's been a long week for me, Shorty. Yes, "alternate." Good catch!

I'm not sure whether the timing sets would swap, but I think it likely. The crankshaft didn't change, and I think it unlikely that they would change the nose of the cam (considering most aftermarket cams are listed fitting AMC sixes in general, it probably never changed over the forty-odd-year production life of the engine family.)

If the timing set isn't any wider, it should fit under the same cover. Also, there are (I believe) some rollerised timing sets out there that will also fit under the OEM timing cover. I'm fairly sure there are "single roller" sets (looks like a bicycle chain) available, and I'm wanting to think that there may be a "double roller" set (looks like a pair of bicycle chains) as well.

So what makes one more quiet than the other?My timing chain is loud,I have started a couple threads on here and other places and the only thing everyone ends up doing is scratching their heads.
Like said I even went as far as to replace the timing set to no avail.
I wonder if it's worth a shot?

The timing chains are interchangeable ... yes. Thats what i did on my 90.

What makes it silent.. well i think pictures are worth a thousand words here:

Old Style:


New Style:


The older style looks like an oversized bike chain to me... The newer looks more beefy, and seems to act more like a roller. There are individual peices of "link" that make up each linked section...

FWIW, when i ordered mine, i asked for the set for a '95 .. even though i obviously have a '90.
Did i notice a difference .. no not really, but then again i wasnt having a problem with my timing chain making noise (even though at the time i thought i was).

The "laminated" chains were designed to be "silent" (no chain drive is completely silent, but the laminated chain comes close.)

The roller chains have more longevity, and don't stretch as much or as soon (I've heard of roller chains going 600-700Kmiles before needing replacement. Laminated chains are usually good for 300-400Kmiles.)

I'd rather have a roller - but if I wanted a quiet ride, I'd have bought a Caddy. The laminated chains came about because people were kvetching about engine noise, and that's just dumb in a truck...

well here's the deal....The timing set I changed out looked like the first pic.The set I installed from the parts store is the one in the second pic.In my case both styles sound the same.....noisey.


5-90 I know its a jeep and it's not supposed to be quiet like a caddy but this noise embarrases me because I take pride in the mechanicals of my jeep(every thing is new under the hood including the engine).I'm tired of people asking me why my engine sounds the way it does.I have a hard time believing that these motors sounded like this off the show room floor.

If I knew for sure that the sound is indeed normal and just another renix quark I will quit worrying about it.....I have a thread open on this subject and I will be posting a sound clip there.

outlander said:

well here's the deal....The timing set I changed out looked like the first pic.The set I installed from the parts store is the one in the second pic.In my case both styles sound the same.....noisey.


5-90 I know its a jeep and it's not supposed to be quiet like a caddy but this noise embarrases me because I take pride in the mechanicals of my jeep(every thing is new under the hood including the engine).I'm tired of people asking me why my engine sounds the way it does.

If I knew for sure that the sound is indeed normal and just another renix quark I will quit worrying about it.....I have a thread open on this subject and I will be posting a sound clip there.

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As long as it's not too loud, I really wouldn't worry about it. Frankly, I wish I could get a gear drive set (I'll probably end up making one...) and I wouldn't care if the gears were spur cut (nice little "whine" to them) or helical (relatively silent.)

Anytime you've got parts that move in relation to each other, you've got to have operating clearances. Anytime there are operating clearances, there's going to be noise. As long as your cam timing is up to scratch, just pass it off as a "Jeep thing" - I've had five RENIX jeeps so far, and all of them made some variety of engine noise.

I know what you mean about taking pride in your mechanicals - I'm the same way. Just know that there are some things you really can't fix - and accept it. Once you do that, you'll be able to relax a little more (it's not my Jeeps that drive up my blood pressure, it's usually my MIL and/or that jackass from the City...)

so all of your renix motors have had some degree of timing chain noise??I don't understand what jeep did to make the newer motors quieter.....supposedly it was the chain design but as I mentioned above I have had both styles in my engine,noise sounds the same.

I dont hear much of any noise on my RENIX ... FWIW.

I have also always heard that the "silent" chains are stronger then the older roller... but 5-90 you seem to think different.

Muad'Dib said:

I dont hear much of any noise on my RENIX ... FWIW.

I have also always heard that the "silent" chains are stronger then the older roller... but 5-90 you seem to think different.

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There is less flexion and less friction on the roller chain - the bushings act like bearings, and "roll" over the sprocket teeth. This reduces wear on the chain (there's not much difference between a "roller" and a "double roller" chain, from a point of wear, tho.)

If you want "silent," pull on your lacy panties and get a belt drive (yes, I know racers use belt drives. Race teams tend to tear down and inspect their engines just about every week, too.) A belt drive is the closest thing to "silent" I've seen. The need for operating clearance is made up for by the elasticity of the drive belt.) I'm just not a fan of belt drives - they want changing every 60K, and that's just tucking about with a basic operating parameter entirely too much. Gimme a chain, or gimme metal gears.

5-90 said:

There is less flexion and less friction on the roller chain - the bushings act like bearings, and "roll" over the sprocket teeth. This reduces wear on the chain (there's not much difference between a "roller" and a "double roller" chain, from a point of wear, tho.)

If you want "silent," pull on your lacy panties and get a belt drive (yes, I know racers use belt drives. Race teams tend to tear down and inspect their engines just about every week, too.) A belt drive is the closest thing to "silent" I've seen. The need for operating clearance is made up for by the elasticity of the drive belt.) I'm just not a fan of belt drives - they want changing every 60K, and that's just tucking about with a basic operating parameter entirely too much. Gimme a chain, or gimme metal gears.

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Im not particularly interested in making anything "silent" per-sey .. sure it would be nice in some aspects, but not expected in any way. Strength i think is the real question here (at least from me).

This may make for a good read:

http://chain-guide.com/applications/1-6-3-inverted-tooth-chain.html

It just seems to me that each individual plates that make each link of the "silent" chain compared to the single plate and roller pin/bushing of the typical roller chain would make for a stronger overall chain preventing stretching for as long as possible. Also, making the overall strength of the chain stronger .. or for a better explanation... able to cope with more hp/torque similar to a double roller set-up. However, i can see the "silent" chain creating more friction, thus increasing wear...BUT then again, it has less impact\sliding... As the article stated clearly above: "Silent Chains wear rapidly without lubrication." Of course our chains are lubed pretty well... but it still makes the friction point pretty obvious.

I have been searching around, and i yet to have found anything that really covers the comparitive depth between the two. To me though it seems to be pretty obvious that the silent chain is stronger... however over time its possible that it will wear quicker then the typical roller. Now maybe a better question is, how strong is the silent compared to the double roller? It may be a decent and cheaper alternative.

Here is the best comparision i have found so far... its a very good read, however the pdf itself i think was put together poorly:

http://www.boschrexroth.com/business_units/brp/_downloads/chain_a_guide_to_inverted_tooth_chains.pdf

After doing more and more reading, i am definetly getting the feeling that the newer "silent" chain is better then the older "roller".

Interstingly, if you look at the 2.5l instructions, it does show the 64 pin chain.