Hello to all,
I just resolved a troublesome issue with the distributor on my car.The following is the failure chain of events.
I had been experiencing a bothersome misfire on cylinder #5 on the last few trips to work and back. The engine was also running erratically in addition to the miss. Adjustments to the timing seemed ineffective.
Today I had the time to do an in depth analysis and found out the following:
Inspection revealed that the "T" shaped end on the rotor had completely broken off. The rotor had somehow climbed up the shaft and began striking one of the contact towers. Amazingly, the Pertronix upgrade kit I had previously installed continued to fire a spark across the 1/4 in gap between the tower pin and what was left of the rotor tip! <<PIC>>
Also, I was uneasy about not being able to locate the missing piece of metal tip. Questions arose - - Would further use cause some damage? Should I try going around the block anyway now that I have the new rotor and cap installed? Answer: YES
It started up nicely running on all six, so I pulled away from the curb confident in the certainty of my fix, - - only to have it stall and quit three doors down.
It would not re-start and did some very strange backfiring. More questions - - Did the little piece somehow mess up my ignition firing sensor ? or had it dropped down and fouled the shaft somehow?
I pulled off the cap and found I was able to quite freely spin the distributor shaft all the way around! - - OH CRAP! Had the shaft sheared? Had the engine thrown the timing chain? Had I just chewed up my sprockets by trying to start it?
Simple answer to this perplexing dilemma: After years of over-tightening, the distributor hold down clamp had lost its ability tightly grip the shank of the housing. <<PIC>> The failure occurred when the upward force of the rotating helical gear drive overcame the ability of the clamp to resist movement, and the distributor climbed 3mm up out of the hole and disengaged the drive keyway! I assume this 3mm was just enough to raise the rotor's swing path high enough to contact the cap and break the end off. (still uncertain about this last part)
One more note for those of us who think we are Hot-Shot mechanics: While troubleshooting this ignition problem I had intentionally backed off the clamp bolt a little so I could more easily tinker with the timing after each lap around the block. SO - - those Kraut-Gremlins then identified this as a perfect opportunity to teach me a thing-or-two.
More Later, - IF - my MB dealer can get me a new distributor clamp from The Classic Center in Los Angeles.
- - Regards, Larry Hemstreet
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Download Attachment: rotor-damage.jpg12.16 KB
