Rotor Gouging Cap

Are you sure that what you are seeing is the rotor "gouging" the cap contacts? Every cap that I've ever seen with some miles on it, will have indents in the contact area....this is normal wear from the spark. Same thing happens with spark plugs, the metal electrode gets worn.

Time for a new cap and rotor if this is all that is happening.

Ian

It's happening with a new cap and rotor and I even went out and got a different brand cap and rotor to make certain. Also if you put your hand on top of the cap while the car is running, you can actually feel it.

Can you see anything that might be keeping the rotor from being fully seated?

I assume that you have checked to ensure that the locating tab on the cap is in the slot for it?

Everything looks pretty good. After 340,000 on the motor I've become quite good at it :)

It's really very strange as I would expect to see some play in the shaft and I do not.

I just replaced the cap and rotor today with the same brand I have always been using. When I started the car I heard whatt sounded like a ticking valve, or an injector making noise. I put my hand on the cap and I could feel a slight knock which corrosponded to the noise. I turned off the engine, removed the cap and rotor and sure enough I could see a very, very light scape mark on the caps electrodes. A little more on one side of the cap than the other.

Thinking I didn't have the rotor/cap seated I tried again with same results. Just for kicks I tried a different brand cap and rotor I had laying around and had the same thing.

If I put my hand on top of the cap and gently flexed it to one side or the other (you can barely feel it move at all), witht he car running I could make the sound change.

I took a look at the old cap and the electrodes had deep grooves in them, yet I don't recall hearing any sound.

Hmmm.... That's odd...

Turns out, I play with the wires on the cap, just twisting them a little while the car is running and the SOUND GOES AWAY!!!

Possible arcing noise due to positioning of the wires?

Even if so, why the mark which to me looks like a slight scrape not the normal mark?

It's all very strange but I think it is fixed.

Went back and reread your original post. It's hard for me to envision how a distributor shaft could get bent, but would that not cause the problem you are experiencing (or were experiencing)? If the shaft is bent the end of the rotor would have a slight orbit and likely contact all of the high voltage contacts inside the cap. You should also see a circular wear patter on the rotor button as well assuming that it has had enough action to show wear.

Yea, that's what had me confused as well. In addition, if the thing was hitting, even on the old cap and rotor, it would have destroyed itself in short order.

I finally found the problem and it was indeed arcing of the wires. I ran the car last night with the hood open and sprayed a mist of water on the cap, the new cap, and I could clearly see arcing between some wires.

I replaced the wires and all is well.

I gues the *marks* on the inside of the new caps electrodes were just normal, although they sure as hell looked like physical contact had been made to me!

Bottom line, wires fixed the problem.