Thoughts on what caused this?

[Warren99]

The part on the distributor cap that touches the rotor looked burnt, and either smashed or melted. I did a little bit of playing in the mud a few nights ago and drove home (maybe 30 min on the road) with no issues. The next day I went to fire it up and it had no spark. After chasing the other parts of the ignition system I finally noticed the strange part on the cap. It also left a little black spot on the rotor but nothing bad looking. I got a new cap from the junkyard and it just had a spring loaded cylinder( might be an aftermarket cap). It fixed the issue, all I'm wondering now is what happened to the old one. The old one wasn't oem, I got it from Oreily's with the rotor, wires and plugs maybe a year ago. My only thought is it somehow got dirty and started getting hot bc of it until it burnt itself out. Any thoughts?

(Black cap is burnt out one, grey is junkyard one)

[watchamakalit]

Did changing the cap fix the no spark issue? The issue see inn the old cap shouldn't effect all spark.  Maybe one cylinder but not all 6. I suspect a different issue.

[Warren99]

Yeah the grey cap from the junkyard fixed it right away, went right back to running fine

[Warren99]

I also forgot to mention, maybe about a month ago it was down on power while driving. It seemed kinda random and sparatic, not like certain gears or rpms mattered but it was more noticeable when it happened in a taller gear. It almost felt like all the spark plugs were still firing, but at like half spark if that makes sense. And it would sorta toggle on and off sometimes within seconds other times it would be fine for 5 min. I ignored it and after some time it either went away or got worse and I just didn't notice it anymore. This never seemed to come back up and everything was fine when I parked it until the next morning when I went to fire it up. Its fixed now but if it happens again I'm gonna have to investigate more, at least I know where to start now.

[cruiser54]

I'll bet that distributor shaft is pretty wobbly.

[Warren99]

That might be it, but when I bought a rotor, cap, wires and plugs they have a year warranty and it I went and got a new cap and rotor. Found out the warranty literally expires on Wednesday

[cruiser54]

Shoulda maybe picked up a spare set.

[Warren99]

As of right now I have a spare cap at least

[cruiser54]

It would be prudent to check the shaft for slop.

[Warren99]

ok thanks

[JMO413]

I would also recommend brass inserts on the cap and rotor of you ever buy again. They tend to last longer.

[Warren99]

Welp I'm getting the same symptoms all of a sudden again. I'll see if the cap contact points look any good, and then I'll check the shaft for slop, which I never did.

[AZJeff]

4 hours ago, Warren99 said:

Welp I'm getting the same symptoms all of a sudden again. I'll see if the cap contact points look any good, and then I'll check the shaft for slop, which I never did.

A shaft that wobbles is going to do bad things to that carbon "button" in the top of the dist. cap.   The carbon button is chosen because it is strong in compression (the rotor spring pushing up on the button), and the carbon is conductive.

 

However, the carbon is NOT designed to deal with "scrubbing" forces that would happen with a side to side motion of the dist. shaft.

[Warren99]

Very useful explanation thanks. In that case its gotta be a loose shaft.

[cruiser54]

easily checked. 

[Warren99]

Already have a replacement distributor, gonna put it on when I get time off of school, but in the meantime, when I checked for slop, there was barely any side to side, but plenty of rotational, and some up and down. Are those any problem, or is just side to side the problem? Btw, the rotor and cap had the same black carbon starting to form.

[motownXJdad]

On 11/29/2021 at 9:39 PM, JMO413 said:

I would also recommend brass inserts on the cap and rotor of you ever buy again. They tend to last longer.

agreed👍