4.0....froze dizzy, now jumps time?

Long story made really short......Dizzy locked up on the highway, sheared off the mounting ears and spun the housing 180*. Spare dizzy goes in, drive it rest of the way home backfiring and bucking. (it was dark, late, and raining, and I was just happy to make it run.)

A new dizzy went in yesterday, timed perfectly and everything. My test drive went perfectly. After an hour, it wouldn't start. I re-set the new distributor (20* out), and ran my errands....came out of the store 20 minutes later to find out that the timing was 20* out again.

Any ideas what's causing this? Why would it be jumping time like this?


BTW....89 XJ, 4.0L, 250k miles. Original dizzy, original timing chain, etc....

Uh, oh.......I'd start by checking the gear on the camshaft. Sounds like you've taken a tooth off.

I saw no signs of damage on the old, broken distributor shaft. Only normal-ish wear on the shaft gears, and no damage on the oil pump tab. Only damage was that the mounting ears were broken off, and for whatever reason, the shaft was froze up.

I think he ment the gear teeth on the camshaft that engage the gear on the distributor shaft. Did you have someone bump the engine while you watched down the hole?

Did you shear the wrist-pin in the new dist.?

Edit: I guess that would be pretty obvious, but have you tried to spin the rotor with the dist. engaged in the motor?

anodyne33 said:

Did you shear the wrist-pin in the new dist.?

Edit: I guess that would be pretty obvious, but have you tried to spin the rotor with the dist. engaged in the motor?

Click to expand...

The new distributor is fine, this is actually one of the 1st things I thought of....

sjkimmel99: I did not check the gears on the camshaft, that's one of the first things I'm going to do this weekend (working out of town, left the Jeep at home). I would think that if the cam gears were stripped, I would see damage to the gears on the distributor shaft.