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TJ 4.0L Timing Chain Replacement


Step 15:  Remove the large sprocket and chain being careful not to turn anything.  Not likely as the engine is hard to turn.

Step 16:  Remove the key from the crankshaft and remove the lower gear.  Note: I could not get the small sprocket off.  I realized I had not removed the key in the crankshaft.  But since my near disaster with the crankshaft threads I was not excited to screw something else up.  I had read the gears were hardened steel so I replaced the top one only on the camshaft.  The lower crankshaft gear looked fine anyways.  I will be doing this on our TJ in the near future and will do both gears. I will provide an update if anything changes.

Step 17:  Replace the chain and gears in the same position making sure the timing marks align.  This is critical!!! Reinsert the key into the crankshaft with some RTV.

Step 18:  Reinstall camshaft bolt and washer tighten the bolt to 68 Nm (50 ft. lbs.) torque.  Useful to put the jeep back into gear at this point.


Step 19:  Remove the seal from the cover with a seal puller.


Step 20:  Install a new seal while supporting the cover.  The FSM states to put some rtv on the outside of the seal before tapping in and to lubricate the seal with oil before installing.  I recommend the mopar tool but you could just use a socket.  I found the tool on e-bay for 24 bucks.

Step 21:  Clean the surface of the timing chain cover and engine block

Step 22:  RTV the timing cover gasket on both sides as my friend says jeeps like to leak.

Step 23:  RTV the bottom of the timing cover where it has the sharp corners.


Step 24: Reinstall cover using the seal installer as a guide on the crankshaft. Be careful not to lose the chain guide.

Step 25:  Tighten the 1/4 inch cover-to-block bolts to 7Nm (60 in. lbs.).  Tighten the 5/16 inch front cover-to-block bolts to 22 Nm (192 in. lbs.).  Tighten the oil pan-to-cover 1/4 inch bolts to 9.5 Nm (84 in. lbs.)


Step 26:  Using the harmonic balancer installer reinstall the vibration damper.  This tool is great, it threads into the crankshaft and has a larger bolt that goes over that one allowing you to put a nut on the outbound side of the damper.  You just crank it on.

Step 27:  Install the crankshaft bolt and washer and Tighten the bolt to 108 Nm (80 ft. lbs.) torque.  I put some RTV under the washer, not sure if that is needed but it looked like there was some there previously.

Step 28:  You are done, reinstall in the reverse, alternator, water pump, thermostat, radiator, fan and shroud.

The FSM said there was a oil slinger on the crankshaft. I did not see one and maybe that has something to do with the missing bolt on the timing cover and previous maintenance. I will update if the TJ has one, if it does I will have to reopen this up and correct it. It helps to deflect oil from the front crankshaft seal.

Things I have learned from this install is to have lots of degreaser on hand to clean things up.  You will notice that timing cover wasn't as clean as I would have liked.  The bolt I found caused a leak and greased up the entire front.  Not sure why someone would not put all the bolts back in a timing cover?  Next time lots more cleaner!



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