Hello all,

This is only my second post on this forum. It’s a long one. I bought a 97 XJ Sport with 132,000 miles on it. The engine was rebuilt at 113,000 by Hopper’s Automotive in Tempe, AZ. I’m in NC, but the PO was in AZ at the time. He wanted to take it on the trails and not worry about the engine so he had an old school Jeep shop rebuild the engine and go through the Jeep. The PO is very meticulous. I went to his house to get the Jeep and he is about as detailed and organized as anyone I’ve ever met.

So here’s where it gets interesting. He told me that after the rebuild when he picked it up, it wasn’t driiving right, didn’t have power, just wasn’t right. So he took it back. They did some testing. He tested the vacuum and it was way low, but there were no vacuum leaks. They determined that they PUT THE CAM IN BACKWARDS!

So they pulled it apart, put it back together correct, and all was good. Except he kept getting code for cam/crank sensors. He replaced both a couple times. Finally replaced the distributor. Still got the code. Then looking at the old vs the new distributor he noticed it was oriented differently, like 90 or 180 different. So he went and got the correct distributor, reset the code again, and never had any problems again.

This was the story he told me. Seemed like an honest seller to me. Jeep drove great.

So I bought it. Drove it 1,000 miles. Took it on a road trip. Took it on some rough mountain forest service roads. All was good.

Then one day, I got the CEL and sure enough, it was crank/cam sensor again. I almost expected it. But it was running fine. I thought, surely it must be a wiring harness, loose/bent connector issue. Something like that. Checked everything out I could. It would clear with battery cable disconnect and then drive fine, but the code came back. Then one day it started bucking. I thought, ok, finally time to get serious about it. And then it just died. Crank and crank but no start. Went through 2 of each crank and cam sensors. Nothing. I pulled a plug and tested for spark. It has spark, but seems intermittent. I checked for fuel at the shrader valve. Fuel pressure seems good, although I didn’t put a pressure gauge on it.

So I decided to take it to the off road shop just down the road from me. They checked it out and noted also that it had intermittent spark. Replaced the crank sensor with a known good one. Still the same. Then they noticed that the distributor wasn’t actually turning correctly all the time. They pulled it off and voila, look down the hole and the gear that drives the distributor is all chewed up.


The gear on the middle of the camshaft that drives the distrubutor gear is all chewed up.

I said, what about doing a top end on the motor? The shop is wary of trying this because of metal potentially circulated though the motor. A valid concern I think. They said best to do a crate motor.

I’m thinking of gambling to see if we can work through this problem, and I’m interested to hear opinions of experienced 4.0 motor people.

The plan would be:
Pull the old pan and see how much metal is in there and how fine. Pull the screen and inspect.
Pull the oil pump and inspect.
Flush the motor.

If all looks serviceable...

Replace the camshaft.
Replace distributor.
Replace the oil pump (which is turned by the key at the end of the distributor shaft, beyond the gear which is turned by the cam gear).

My theory is that the gear got damaged either when the cam was installed wrong, or when the incorrect distributor was installed; but had just enough meat left on it to run... until now.

Any experienced motor peeps have thoughts on this? The xj is real nice other than that one little gear