Replacing Timing Chain

Can someone give me the correct procedure for replacing the timing chain? also if i replace the chain do i also have to replace the gears or can i keep the old ones on there? I am just wondering is there a way of getting the chain off without removing the cam sprocket or crank shaft sprocket.

Thanx,

Eric

Anyone?

thanx

Gears are all metal, so you should not need to replace them. However, you cannot get the chain off without removing the sprockets. (Or, if you can, your engine shouldn't be running -- and you definitely cannot get the new chain ON with the sprockets in place).

The short version is, remove front of engine, replace chain, reassemble. To do the job, you really need a tech manual. If you don't have a factory service manual (FSM), head to the auto store and buy Chilton's or Haynes Cherokee repair manual. They should spell out the procedure and give you the necessary torque specs, etc. Too long to try to type out here, and I'd forget something important anyway.

Hi Eric,

To my knowledge you can't remove the chain without removing the sprockets. Even if you could, as long as you've taken the time and energy to even get to the mess you might as well change the sprockets as well.

The absolute most important thing to remember about replacing the chain and sprockets is to make sure the timing marks on the existing sprockets are perfectly aligned. You do this (on a 4L engine anyway) by first rotating the engine (at the crankshat) until the marks are across from each other as closely as possible. My limited eloquence prevents me from describing this as clearly as the pictures in a Haynes or Chilton's would, so I strongly recommend you consult one of these manuals to visualize the sprocket alignment. You know you will have aligned them correctly if the marks fall into a straight line that bisects the crank and camshaft axis. Also, on the 4L engine, I think there will be 14 links (don't hold me to this) between the 12 o'clock and 3 o'clock position of the camshaft sprocket and crankshaft sprocket, respectively. Once you have the sprockets aligned, simply pull them off in unison along with the chain directly from the camshaft and crankshaft stubs. Don't move either shaft as you remove the sprockets and definitely don't move them after you have removed the sprockets.

When replacing, I've found that it helps if I first lay the sprockets on the garage floor with the chain wrapped around them and then position them as if they were on their stubs. Maintain the sprockets' relative positions and take the entire assembly and place them precisely on the stubs. I believe (hmmm) the oil slinger goes on the crankshaft first, so don't forget that.

Erik
88 Comanche

Regarding Erik's post above, the books call for you to count pins rather than links; there should be 15 between the marks. The FSM calls for the gears to be disassembled and reassembled with the marks aligned facing each other, after which you turn the engine so that the marks are now approx. at 2 o'clock for the cam gear and 5 o'clock for the crankshaft. At that point, there should be 15 pins between the marks. For the same procedure, Haynes puts the marks at a little past 12 for the cam, and 3 for the crank, but the pins are still 15. I don't think the exact position matters, as long as the chain is fully wrapped over the marks on both gears.

The oil slinger goes on after the sprocket.

Haynes and the FSM both give pretty good instructions on all this, and it's definitely worth having one of these on hand.

Eric,

Pins. Yes. Not links! Arrgh. At this point you can probably appreciate why all of us recommend you consult a manual.

Erik
88 Comanche

thanx guys, i was just wondering cause mine has over 200k on it and i got a new one laying around.

eric

I am sure the kit comes with new gears. Always replace the timing gears with the chain. Everything wears as well as the chain. While you're in there replace the front crank seal too-

I did this not too long ago to my 4 popper. It isn't too bad for the 4 pooper.

Judd W. VA said:

I am sure the kit comes with new gears. Always replace the timing gears with the chain. Everything wears as well as the chain. While you're in there replace the front crank seal too-

Click to expand...

I replaced mine a week ago when I had the engine on a stand.

You can get just the chain, although for the extra $40, I replaced the sprockets so I wouldn't have to tear into it again.

The sprockets should come off pretty easily. MAKE SURE YOU DON'T LOSE THE PILL OR THE SPRING BEHIND THE CAM SPROCKET BOLT! Assuming your engine has them......I've heard rumors that not all 4.0Ls have them.

And yes, replace the front seal as well.