Jeff in VA
<---respect
- Location
- Richmond, VA
Thought I’d throw up a little old-school tech for the group. Although most of the component removal I did wasn’t absolutely necessary, I was doing some other maintenance and mods at the same time, and the pics are a lot better to see what I’m describing.
After listening to my timing chain slapping around for the last 30K miles, I decided to replace it over the weekend. Special thanks to Chuck (cmcolfax) for giving me half of his garage to work in :cheers: If anyone’s thinking about doing this who hasn’t done it before, I’ll try to make this as all-inclusive as I can. Feel free to ask any questions if I don’t cover everything (or if I left anything out….I was working solo and taking pics as I thought I should for a good writeup). My MJ is a 2.5L, but both the 2.5 and the 4.0 share the same bottom end, so the procedure is identical for either engine. Your alternator bracket will be a bit different than mine, and I don’t have AC so I didn’t have to work around AC lines or a condenser, either. YMMV
OK, here we go…here’s the patient, my 87 MJ 2.5L with 174K miles on it, and a slapping timing chain:
Start by removing the battery, drain the cooling system and remove the radiator (and if you have AC, deal with the condenser somehow):
With the radiator out of the way, you can see the harmonic balancer bolt that needs to be loosened. At this point, leave the serpentine belt intact (the tension will help hold the balancer stationary while you loosen the bolt):
There’s a couple different ways to break that bolt loose (which I won’t mention), but I prefer this for a quick-and-easy method:
Break the bolt loose, but do not remove it yet. Now you can remove the serp belt. First, loosen the tension in the belt via the power steering pump (all bolts are ½” hex head, FYI). There are 2 bolts to loosen that hold the pump, one trunion nut that holds the tensioner bolt, and one tensioner bolt you turn counter-clockwise to move the pump toward the engine. Remove the airbox for complete, hassle-free access to these. The two bolts in the back of the pump are these:
The trunion nut is in the front, at about 7 o’clock:
And the tensioner bolt is under the pump, pointing toward the driverside fender. Turn it counterclockwise to loosen the pump (you may have to persuade the pump to move if it hasn’t in a while):
Remove the belt. At this point, I also removed the radiator shroud, fan, and water pump pulley for better access to the timing cover. Next step (if you haven’t already) is to set the engine to TDC, using the harmonic balancer bolt that you loosened above. Rotate the engine clockwise with a ¾” socket until the timing mark on the balancer lines up with the “0” mark on the timing tab on the cover:
Verify TDC by rotor position. The rotor tip should be pointing directly at the #1 tower on the distributor cap:
Once you are at TDC, remove the harmonic balancer. Use a balancer puller, like this…
It attaches to the HB and pulls it off the crank snout cleanly and easily. Do not redneck engineer this process, and do not rotate the engine.
With the HB off, you can see what they are famous for….they are a two piece construction, with rubber sandwiched inbetween the inner and outer parts, and the rubber starts to migrate out, and start gringing away on the front of the timing cover (not a good thing). Here’s what mine looked like:
After listening to my timing chain slapping around for the last 30K miles, I decided to replace it over the weekend. Special thanks to Chuck (cmcolfax) for giving me half of his garage to work in :cheers: If anyone’s thinking about doing this who hasn’t done it before, I’ll try to make this as all-inclusive as I can. Feel free to ask any questions if I don’t cover everything (or if I left anything out….I was working solo and taking pics as I thought I should for a good writeup). My MJ is a 2.5L, but both the 2.5 and the 4.0 share the same bottom end, so the procedure is identical for either engine. Your alternator bracket will be a bit different than mine, and I don’t have AC so I didn’t have to work around AC lines or a condenser, either. YMMV
OK, here we go…here’s the patient, my 87 MJ 2.5L with 174K miles on it, and a slapping timing chain:
Start by removing the battery, drain the cooling system and remove the radiator (and if you have AC, deal with the condenser somehow):
With the radiator out of the way, you can see the harmonic balancer bolt that needs to be loosened. At this point, leave the serpentine belt intact (the tension will help hold the balancer stationary while you loosen the bolt):
There’s a couple different ways to break that bolt loose (which I won’t mention), but I prefer this for a quick-and-easy method:
Break the bolt loose, but do not remove it yet. Now you can remove the serp belt. First, loosen the tension in the belt via the power steering pump (all bolts are ½” hex head, FYI). There are 2 bolts to loosen that hold the pump, one trunion nut that holds the tensioner bolt, and one tensioner bolt you turn counter-clockwise to move the pump toward the engine. Remove the airbox for complete, hassle-free access to these. The two bolts in the back of the pump are these:
The trunion nut is in the front, at about 7 o’clock:
And the tensioner bolt is under the pump, pointing toward the driverside fender. Turn it counterclockwise to loosen the pump (you may have to persuade the pump to move if it hasn’t in a while):
Remove the belt. At this point, I also removed the radiator shroud, fan, and water pump pulley for better access to the timing cover. Next step (if you haven’t already) is to set the engine to TDC, using the harmonic balancer bolt that you loosened above. Rotate the engine clockwise with a ¾” socket until the timing mark on the balancer lines up with the “0” mark on the timing tab on the cover:
Verify TDC by rotor position. The rotor tip should be pointing directly at the #1 tower on the distributor cap:
Once you are at TDC, remove the harmonic balancer. Use a balancer puller, like this…
It attaches to the HB and pulls it off the crank snout cleanly and easily. Do not redneck engineer this process, and do not rotate the engine.
With the HB off, you can see what they are famous for….they are a two piece construction, with rubber sandwiched inbetween the inner and outer parts, and the rubber starts to migrate out, and start gringing away on the front of the timing cover (not a good thing). Here’s what mine looked like: