HELP - '96 XJ 4.0 distributor making noise.

Hi Guys,

First time poster - I try to read posts as time allows.

I am getting a whirring/howling (insert your own sound effects here) sound from the distributor of my '96 XJ with the 4.0 HO. I first noticed it this morning and it went away after a minute or so. I drove to work and didn't notice the noise and all seemed to be
behaving as expected. The noise could have been there but I did not notice it over the road/wind noise. I went outside after work tonight and started it up - same noise again. The noise is similar to that of a bearing in a pulley going bad. I can feel the distributor vibrating if I put my hand on top of the distributor cap. I let it idle a minute or two and the noise would come and go. Once the noise stopped, if I would bring the revs up just a bit for a couple seconds and let it return down to idle, the noise would return. I pulled the dist cap before I left work tonight and both the cap and rotor look brand new still (I changed the plugs/cap/rotor/wires @ around 87K miles and it currently has 93.8K on it). There was no visible sign that anything is wrong from what can be seen by just pulling the cap and rotor.

Any thoughts on what would cause such behavior? Distributor need replacing? Oil pump? Note that the oil pressure has been fine and has not changed at all from normal. I would fix it myself if I was positive what the exact problem was..

Thanks in advance,
Rich
96 Jeep Cherokee 4x4 - Auto w/ 4.0 HO
3" lift w/ 31x10.50
North of Boston.

Did you notice if the screws holding the cap were loose? I had one loosen up and had a thumping noise,Tightened them up and all was well.
Wayne

I had thought the same thing when I first realized where the noise was coming from. Both of the screws holding down the cap seemed tight when I lossened them to take a peak under. And they are definitely tight now after putting it back on. Thanks for the suggestion.

Bad bushing

There is a bushing or bearing where the distributor shaft comes up through the distributor housing. I haven't seen one go bad on an XJ but what you describe fits the symptoms on other cars. Take the distributor cap and rotor off and look for metal particles. Then shake the shaft around and look for looseness, runout. If it's loose at all then replace the bushings or the whole distributor ($59.99 NAPA). Hope this helps.

check on that worn bushing ASAP, we had a chevy pickup come in to our shop a while back with this problem, it had actually ate all the teeth off the drive gear and all that metal is now floating around somewhere in that poor truck's engine. you definetly don't want that.

if you are going to get new parts

Rich,
The dealership in Medford (Grava) is usually 20% cheaper than most other stealerships in our area. Also, there's an AutoZone right down the street if you need something that the dealership doesn't have.
Also, the young guy at the parts counter is a mustang guy...
-Tom

Thanks again for the heads up Tom. I'll let you know how it works out.

Update!

Just wanted to update the forum on my issue. The distributor was pulled and sure enough it turned out to be the problem. You could barely spin it by hand - it really took a lot of effort just to get it moving. No other wear was evident which was nice. A new distributor was put in and all seems well again.

Next is to get rid of the clunk when taking off from a stand still...driveshaft is my guess.

Thanks to all who responded with your input and suggestions.

clunk

check your motor mounts first!