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Timing Chain Write-up

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Timing Chain Write-up

Post  CrawlingForward on 4/23/2012, 12:50 pm

Did this a while ago, but figured I'd post it up here.

Additionally, when I pulled off my timing chain, I realized my timing chain was set up incorrectly and I therefore had to individually set my all my timing components. So if anything in this write-up seems incorrect or if a component suddenly changes, let me know and I’ll try and correct or make a note of it.

This was in a ’95 YJ 2.5L, so be aware that if you have a 4.0, there’s less room, and therefore something might be different.

All in all, it’s not that bad so long as you don’t change anything’s position once you have the chain and sprockets off. If I hadn’t had to take all the additional steps, it could have been done in an afternoon. I also replace the chain, sprockets, tensioner and oil seal. You may not need to replace all of those components.

Chock all 4 wheels and put the Jeep in gear with the parking brake on. I did a lot of putting the Jeep in and out of gear depending on how easily I wanted the engine to turn over/not turn over.


Disconnect battery


Remove the 4 nuts that hold on the fan clutch (you’ll most likely need an open ended wrench, as a socket won’t fit)


Once you’ve removed the fan and fan clutch, go ahead and take off the 4 bolts that hold on the radiator shroud. With the fan clutch out of the way, you should be able to wiggle it around the radiator hose without needing to disconnect it.



Next, with the Jeep in gear and the serpentine belt still on, break loose the harmonic balancer bolt. It’ll move a bit, but eventually engine compression will give you the resistance you need.


Once it’s loose, you can remove the serpentine belt by breaking loose the tensioner pulley bolt and then turning out the tensioning bolt on top. Once you’ve got enough slack, you can remove the serpentine belt.




Next step is to find Top Dead Center. It sounds more complicated than it is.

First, remove all your spark plugs, disconnect the wire to the coil, and put the transmission in neutral. Make sure to label your plug boots so you know exactly where they go when it’s time to put them back. (I love WhiteOut for this purpose) This will also make sure you can easily identify the #1 post on your distributor.


Next turn the harmonic balancer bolt (3/4” socket) clockwise until the notch on the harmonic balancer lines up with the zero mark next to it.



Now, the notch can and sometimes does slip, as it can sometime separate from the rubber. If you suspect this may be the case, you can verify the piston is at the top by inserting a long screwdriver into the sparkplug hole and slowly rotating the harmonic balancer until you feel the screwdriver come to the peak of travel. (Be careful, though, that you don’t accidentally get the screwdriver caught. It’s easy to do)


Once you’re certain that the piston is at TDC, you need to make sure that it’s on the combustion stroke (as opposed to exhaust stroke). You do this by verifying distributor rotor position. First, mark a white-out mark on the distributor housing directly underneath the number 1 cylinder plug wire. Remove the two screws holding on the rotor cap and look to see if it’s pointing at the mark you just made.



Mine was pointing 180* off (see the white mark at about 4 o’clock?). If this is the case, you need to rotate the harmonic balancer one more full rotation until the mark is at zero again and your rotor is pointing at your mark.



Congrats! You are now at TDC! Go ahead and reinstall your spark plugs and put the Jeep back in gear.

Next step is to remove the harmonic balancer. Make sure you get the correct tool/adapters for this. I originally used the tapered adapter with the bolts that thread into the balancer, which put pressure on the threads of the central bolt-hole, which needed to be retapped during re-installation.


I ended up using the kind that grabs the balancer that grabs the balancer from behind and pulls it off, mostly because the bolts from the other kit didn’t fit.


Once the balancer is removed, the next step is to prep for taking off the timing chain cover. The idea given to me was to make a representation of it on cardboard and place the bolts in the appropriate spot (there are a number of different types of bolts that need to go back where they came from)



Once all the bolts are off, go ahead and pull the cover off to reveal...TADA! The timing chain!

_________________
95 YJ, 2" BDS w/ 1" shackle lift, 235/85/16 BFG ATs on Cherokee Icon wheels, SYE w/ Tom Woods Driveshaft, 4.88 Ford 8.8, locked/locked
2010 JK Unlimited, Islander Edition

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Re: Timing Chain Write-up

Post  CrawlingForward on 4/23/2012, 12:51 pm

Time to inspect if your chain has extra slack/stretch, is worn, chipped, pitted or has rust or corrosion. It’s recommended the chain be replaced every sixty to hundred thousand miles, but typically they will last the life of the engine without much issue. If you’re this far and have any doubt, you might as well replace it.

For the following steps, make sure to stuff a rag in the oilpan opening to make sure no debris fall in.

Now you can go ahead and unbolt the camshaft sprocket bolt, using the engine compression to keep it from moving.



Next remove the timing chain tensioner for inspection. Do this by relieving the tension by turning the un-locking mechanism and removing the c-clip holding it on the peg. Check for excessively deep grooves or the spring being worn enough that it doesn’t create proper tension. Replace if you see the need.



Next you can go ahead and pull off the timing chain and both sprockets as a unit. Take off the oil slinger and you are left with this!


Now set the old timing chain next to the new one and set up the new one to match the old.

(Both timing chains should look like the one on the right. If you’ve noticed, mine wasn’t and that was part of my running issues). When the timing chain is on correctly, when the timing mark on the camshaft sprocket is at 1 o’clock, there should be 20 pins between the marks, as represented in the diagram (1996 and earlier).


Once it’s set up correctly, you can install the new timing chain set and/or chain tensioner.

The camshaft sprocket has a dowel that will only let it be installed one way, and the crankshaft sprocket has a notch that does the same. So if it fits and you can still pass the 20 pin check, then you’re all set!


To reinstall the timing chain tensioner, move the tensioner block forward, lock it in place andslide it on and install the c-clip. Then unlock it to put tension on the chain and pick up the slack.

Next reinstall the oil slinger and the camshaft sprocket bolt, tightening to 80 ft lbs.



Time to prepare the cover for reinstallation!

Go ahead and clean up the old cover by scraping the old gasket off and getting rid of any grit and grime.


Do this on the engine side as well, but make sure to cover the chain and sprockets to make sure you don’t get any grit into it.


If you’ve got everything apart, you may as well replace the oil seal in the cover. Not required, but take a look and decide if you’d like to.

If you do, drive out the old seal. The manual recommends a screwdriver.


This, however, was completely ineffective. I ended up just vice-gripping it and using a mallet to pop it out.


Before putting in the new seal, make sure to coat it with a thin layer of oil.


Then make sure it’s placed evenly and drive it in with a piece of wood.


Now that it’s clean with the new seal in it, it’s time to apply the RTV. Put a thing bead on the sealing surface and around the bolt holes and smooth it out with your finger. Make sure to use a black, oil-safe RTV!


Next throw on your gasket with another thing layer of RTV (I had to use my dental tools to keep the gasket in place while the RTV set.)


While that’s setting, trim off the remaining tabs of the oil pan gasket sticking out and replace them with liberal amounts of RTV.


Next pre-lubricate your new (rubber) oil pan gasket with a thin layer of oil and place it on the lip of the oil pan. (FYI, I had to cut off certain nubs that didn’t correspond with my oilpan. The screwholes were the primary aligning factor for me)


Now reinstall the oil pan, putting the screws back in the appropriate holes using your handy-dandy diagram! Install all bolts hand-tight and then torque to 16ft lbs on the nuts and 7 on the oil pan screws.


Then gently work the harmonic balancer back on (Made sure to line up the notch with the tab, or “wooddruff key”). Try and get it on without bashing on it, as that can damage the bearings. If needed, lightly tap in a circular pattern with a soft mallet to nudge it on, but only until it’s on enough to get the bolt and washer screwed in a few solid threads. At that point you can work the balancer on by screwing the bolt back in. Torque to 80 ft lbs.




Now reinstall the serpentine belt (don’t forget to tension), the fan and fan clutch, and radiator shroud. Reconnect your battery and you’re all set! (You may want to reset your PCM, but that’s up to you).

_________________
95 YJ, 2" BDS w/ 1" shackle lift, 235/85/16 BFG ATs on Cherokee Icon wheels, SYE w/ Tom Woods Driveshaft, 4.88 Ford 8.8, locked/locked
2010 JK Unlimited, Islander Edition

My JeepForum build

Building a Jeep is like masturbating on pain killers. You enjoy the time you put in, but you'll never actually finish.
avatar
CrawlingForward
Moab Dessert

Posts : 822
Join date : 2011-12-09
Age : 31
Location : Flushing, MI

http://www.geoffreymarsh.com

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