Timing Chain Time - JeepForum.com
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post #1 of 7 Old 06-19-2011, 03:31 PM Thread Starter
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Timing Chain Time

So I've got about 165k on the 4.0 and I know I have a few issues to tackle.

The first thing I know needs to be corrected is the rubber on the harmonic balancer is coming out. As long as I'm in there, I'm thinking I should go ahead and replace the timing chain.

So here are the questions:

1. If I'm replacing the timing chain, should I go ahead and replace the sprockets as well? That is, should I purchase the whole set or just the chain.

2. I've read where you don't have to remove the oil pan in order to to do the timing chain - however, as long as I'm messy, should I go ahead and do the seal on the pan?

2a. If I'm going to do the oil pan, should I just go ahead and do the oil pump?

2b. If I'm going to do the oil pan, should I just go ahead and attempt the rear main seal? It might be leaking, but it might be the oil pan/valve cover.

3. Lastly, if I'm going to have the bottom off the motor, obviously going to inspect everything... Should I go ahead and re-do the gasket on the valve cover and inspect the topside. (btw, I'm a noob so I'll probably just say "wow, looks cool" and put everything back together...)

Any suggestions on parts sourcing and part numbers will be helpful. Also, beside the harmonic balancer puller and the pullers for the timing chain, are there any other special tools I'll need to rent?

FYI, I've got O'Reilly and Napa local.

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post #2 of 7 Old 06-19-2011, 03:36 PM
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I get the sprockets too, its only a little extra and you already have it apart. I did mine on my 2.5 and I didn't have to take the oil pan off just had to loosen the front 4(?) bolts.
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post #3 of 7 Old 06-19-2011, 05:10 PM
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Get the timing chain SET. This will include new sprockets along with the chain.
As far as everything else goes, it's up to you. If it is leaking oil etc, then by all means fix it.


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post #4 of 7 Old 06-20-2011, 08:21 AM
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Pan gasket replacement will depend on the condition of the gasket where it meets the timing cover. I had already replaced mine with the one piece Fel-pro one so there was no need. Had it been the original, I would have just replaced the pan one too since it just crumbled when I removed it the first time. If you do drop the pan, I would definitely replace the rear main seal as it is easy to do and you already have the pan out of the way. I did not replace my oil pump as it is still putting out 35-40 at idle. Make sure you get the one piece pan gasket. I would also do the valve cover as they are notorious leakers and the crank ventilation orifice likely needs to be cleaned.

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post #5 of 7 Old 06-20-2011, 08:30 AM
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I did my 2.5l timing set not long ago. Got all parts from rockauto. The gasket that comes with it is junk. DONT use it. Its supposed to mate w ur stock oil pan gasket but it don't. Get a new oil pan gasket (so its all 1 pc) n drop the pan w the timing cover. As far as the rest I've always been told don't touch the rear main unless its leaking. Just fyi its a 2pc seal n not as easy as u may think to replace.

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post #6 of 7 Old 06-20-2011, 11:15 AM
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like 1tuffyj says the rear main seal can turn into a goatrope. if it ain't broke don't fix it.
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post #7 of 7 Old 06-20-2011, 04:11 PM
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Always replace the chain and the sprockets. Chances are your original cam gear is toast, anyway: you'll see.

Absolutely replace the rear main seal while you are in there. It is not hard, and you are going to have to to it eventually anyway. Pulling the pan is the hardest part, and you have to do that anyway if you are changing the timing chain.

Don't lose or forget the spacers on the timing cover and don't lose or forget to reinstall the cam tensioner spring and plunger.
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