Camahaft interchange 4.2/4.0

[Gordon-B]

First of all sorry if this has been beaten to death but I'm not sure what I should do in the situation I've gotten into.

I have a 2002 4.0 engine. Not a stroker. I needed to put a new headgasket on it and at the same time figured why not replace the cam and noisy lifters I had.

Ordered a Comp cam/lifter kit, 4.2 timing kit, and spring pin retainer kit and slammed it all together. It runs mostly good. That was all 2 years ago.

Last week I check my oil and find it a quart low. Put in some oil and suddenly I have a massive oil leak. Turns out the spring pin cam retainer wore a hole in my timing cover and oil is coming out.

Well Shit.



So what do I do from here?


The way I see it I have 3 options

1) Cover the hole with epoxy, and hope the chain and tensioner is enough to keep the cam where it belongs

2) replace the cover with a cover from a 4.2. Hopefully I can do this without removing the grille again because I just had the AC charged a few months ago.

3) tear the whole thing apart and put in a stock cam and new lifters, buy a new cam retainer plate, and 4.0 timing set, hope the head doesn't need to be skimmed again.




Gotta be honest, #3 isn't likely to be happening. I'm leaning towards epoxying ove the hole and hoping for the best, but I'll replace the cover if everyone here is in agreement that it would be a bad idea to just leave it as is.


Help?



Thanks everyone

[Gordon-B]

I assumed that the older covers would be steel, but they appear to all be aluminum as well. What's the difference then? Wouldn't the cam wear out the cover just the same on a 4.2? What's up?

[SilverXJ]

Later 4.0L timing covers lacked the little nub that the cam pin rides against. You didn't provide pics so I assume that the bolt may have rubbed a whole in the cover.

I would replace the cover with an earlier one with the little nub/bump for the cam pin. Also make sure that the cam fully seats in the block and isn't held forward by the cam plug. Being factory that shouldn't be an issue. Inspect the pin to see if the side that touches the timing cover is smooth.

[Gordon-B]

sorry, no pics, but the hole is only the diameter of the pin, not as big as the entire bolt.
If I remember correctly the pin was 3/16" diameter.

I have researched further and found that the older style covers did not have provisions for the "snubber" or whatever you want to call the plastic tensioner type device installed in the timing cover.
Also, the older style isn't compatible with the alternator bracket on newer motors from what I can tell.

Is it really so critical to have the pin?
the spring rate on the pin spring was very weak from what I remember. it couldn't have taken more than 3-5 lb of force to fully compress.

shouldn't the oil pump drive/crank position sensor keep the cam in place too?

as I said, I've daily driven the jeep for around 2 years like this. The cam is fully seated from what I can tell.


I promise i'm not trying to start an argument, but I really don't want to tear the engine apart when it's mid 30's outside if there's no real benefit.

[SilverXJ]

I have researched further and found that the older style covers did not have provisions for the "snubber" or whatever you want to call the plastic tensioner type device installed in the timing cover.

Maybe the 258 cover, but all the 4.0L covers I know of have the provision for the snubber.

Also, the older style isn't compatible with the alternator bracket on newer motors from what I can tell.

I'm not that familiar with the TJ accessory lay out so I can't offer any insight there.

Is it really so critical to have the pin?

Yes!

shouldn't the oil pump drive/crank position sensor keep the cam in place too?

Technically that and taper grind on the cam lobes should. But it doesn't. You have seen that it can wear a hole in the cover so, there is some force acting against it.

I really don't want to tear the engine apart when it's mid 30's outside if there's no real benefit.

Not really tearing the engine apart, just replacing the timing cover.