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Cashcrazy 05-29-2013 09:57 PM

4.2 timing chain replacement?
Does anyone know of a good write up on how to replace the timing chain on a 4.2 YJ? The seal on the timing cover is leaking and it would be a great time to replace the chain while I have it all apart.

jokerchief462 05-29-2013 11:03 PM

1 Attachment(s)
Here is a little help from the FSM. Pay close attention to the NOTE and count.

Take it all apart so you can see the chain and timing marks and align like the picture. When you have removed the old and installed the new read the note and count. Should be good to go. It will not run right one tooth off.

Cashcrazy 05-30-2013 08:26 AM

Thanks. Not getting everything lined up is my main concern. Do I need to mark the harmonic balancer before I remove it and reassemble in the same position?

jokerchief462 05-30-2013 09:52 AM

The harmonic balancer should have a jetway to reign on install. But it won't hurt to mark it.

jokerchief462 05-30-2013 10:46 AM

Not jetway I meant KEYWAY on the crank to align it.

Cashcrazy 06-01-2013 11:07 PM

I picked up a timing gear/chain set today and started pulling everything off the front end to get to the chain. The set was made by S.A. gear. Has anyone used a set from them? I can find good and bad reviews online about them, mainly from non-jeep V8 users. I went to three part stores and it was the only one in stock and they all claimed their brand was the best so I don't really know what to believe. The engine has 120k and the timing chain cover seal is leaking. The original chain is not giving me any problems, but it is a great time to replace it. Any input on this.

Craigthemann 06-02-2013 10:18 AM

I just completed a timing chain replacement on my 90 Yj 4.2. I was worried about the alignment as well but there really is nothing to it. When you remove the timing chain cover you will quickly notice the timing marks on the crankshaft and cam gears, they each have a little dot. Reinstall the crank bolt and rotate the engine to get the dots to line up. Once lined up, remove the existing and replace with new. To confirm that the new set is properly installed, rotate the engine and do the 1 o'clock/3 o'clock thing and count 15 chain pins. If its correct, you're good. Jokerchief helped me a lot with this by the way.

Cashcrazy 06-02-2013 02:20 PM

Thanks for the info. I have everything out and I am ready to pull the harmonic balancer. I had to make a parts run for some new hose. I hope to get this finished today.

Cashcrazy 06-02-2013 04:28 PM

Neither of my two impacts will break the harmonic balancer bolt loose. Anyone have any tips on how to use a breaker bar and keep it from spinning?

Cashcrazy 06-02-2013 09:06 PM

I finally got it by putting a piece of pipe into the flywheel to hold it in place. Thanks for all the info.

I think it was time for timing gears.

Is the harmonic balancer supposed to have this groove? It looks like this is where the seal on the timing cover touches, but I didnt know if it is supposed to have an actual groove.

Cashcrazy 06-03-2013 01:28 PM

I believe this is my last question that I need answered before I can finish the job. My manual states the cam sproket should be 45-55 ft lbs and the harmonic balancer bolt to be 80 ft. lbs. No problems there. This is what I found for the timing cover torque specs:

Timing Cover to block bolts - 60 INCH lbs. (I converted to 5 ft. lbs.)
Timing Cover to block studs - 16 ft lbs.

The cover uses small bolts (3/8" head I believe) and a few larger bolts. I only had one of what I would call a stud. Two of the bolts are used to support the alternator bracket. Can someone please clarify which bolts need to be torqued to what amount? I usually follow torque specs, but 5ft lbs seems low enough to get an oil leak.

jokerchief462 06-03-2013 06:56 PM

1 Attachment(s)
Here is the info from the FSM

Cashcrazy 06-03-2013 10:43 PM

Thank you for sharing. I found out tonight the harmonic balancer bolt was stripped. That may be why my 1/2" impact wouldn't break the bolt loose. I am guessing it was not threaded properly and then forced in the rest of the way. I was able to clean it out with a tap. I will try that after all the other parts are back on.

Craig was very helpful and let me know the groove should not be on the balancer and told me about a repair sleeve. My next question, the harmonic balancer was rubbing the timing chain cover. What causes this and how can I correct it?

jokerchief462 06-03-2013 10:52 PM

2 Attachment(s)
Never seen that before so something is wrong. Is the outer part of the balancer pushed back for some reason. The rub looks like it is coming from the rubber damper.

If it will still do it when reinstalled you may have to find another one.

Here are the two pages you need.

Cashcrazy 06-04-2013 09:09 PM

I had a little time to work on the Jeep tonight. I was able to get the timing cover cleaned up and install the new oil seal. I also inspected the rub mark. It looks like the rubber is causing the problem. Please correct me if I am wrong, HB appears to be a steel center section, then a rubber layer, and steel on top. I believe the rubber layer is worn out and wobbling/stretching as the engine runs. That means I need another HB. The surprises never stop.

Can anyone tell me if this is the right harmonic balancer. The guy at quadratec said it was but I am hesitant since it does not say 4.2 for the motor.
Original Replacement Parts 33002920 - Vibration Damper for 84-04 Jeep® Vehicles with 4.0L 6 Cylinder Engine - Quadratec

I can't tell everyone how much I appreciate the help.

Cashcrazy 06-04-2013 09:22 PM

If someone knows a better place to buy the harmonic balancer let me know. Unil then, here are a couple of pics of some visible wear.

jokerchief462 06-04-2013 10:20 PM

Here is a link call them on the phone. When you open the page look on the left bar and choose used Jeep parts and just look at the pictures. If anyone has one of these at a decent price they should have one. Let me know if you need more research for the part.

Collins Brothers Jeeps and Jeep Parts

I bought my used parts bell housing and stuff for an external slave cylinder conversion last year. No issues drop shipped as promised the parts were just fine.

mschillingii 08-18-2013 03:32 PM

okay i know this is a little old but i'm in middle of the same exact thing, the local part stores couldn't find it, i went to s&s automotive in st louis and they found it for $89. Part number 102007. yours did the samething as mine the rubber spins and moves the balancer and and it contacts the cover, and it also makes the timing mark off. my problem is the center bolt is stripped and tried to clean the threads but no go so i'm moving up to a 9/16-18 bolt and hopes that fixes mine

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