Engine Fire - Distributor Related - Pics Included

[patrickt]

Bob M. (CCX 33239) and I had been emailing each other over an engine fire that he had and how the distributor may have played a role in it. He had some trouble getting a new thread started and asked me if I would do it for him -- so here it is:

Sometime back, I had a significant engine fire that was initiated by a failure in the disributor cap. The carbon center electrode basically "exploded" and sprayed the inside of the cap with carbon dust. I believe this triggered a misfire that resulted in a backfire through the carb. Concurrently, I had a small fuel leak between the fuel pressure guage and the regulator. The result was that I suddenly started dropping cylinders along with smoke exiting from the hood scoop. Thanks to a 2 1/2 lb Halatron extinguisher, the damage was confined to the engine compartment (wiring; fuel lines; and weeks of cleanup). I have had some discussions with PatrickT about this and he suggested that I start a thread that might be of use to some of the members. Attached are some photos of the inside of the cap. Of note are 1) the center electrode is totally gone; 2) almost all of the carbon dust splatter is concentrated between the #4 and #5 plug locations; and 3) the third photo shows the opposite side of the cap has almost no carbon splatter. From the above, I have concluded that the electrode went in one motion, and not over a period of time. Also, this cap had only about 2-3k miles on it. I hope this might be helpful to someone out there.


Bob

[ERA Chas]

Thanks to Pat and Bob M.

There's virtually no way for any of us to foresee a catastrophic part failure like that other than to change many parts every year. But that's still no guarantee.

The REAL lesson of the story is to NEVER leave the driveway with a leak of any kind-especially fuel. Have to be diligent about that to prevent this sort of thing.

[Woodz428]

What did the rotor look like?? If the contact had just broken off, I wouldn't think it would have sprayed the carbon in such fine pieces. Was the center of the rotor offset some and caused it to "whittle" the carbon down. I've pulled rotors that were slightly bent off to one side, never thought about it doing that kind of damage, saw it as more of a "spark inhibitor". Glad to hear that the damage was less than it could have been under the circumstances.

[Blas]

I have seem something similar to this before. It was caused from the contact on the top of the rotor is not making the proper contact with the carbon contact at the center of the cap. With a gap there, arcing will occure between the rotor contact and cap and very quickly destroy the center carbon contact assembly. I mention this because there looks to be a substantial amount of carbon on the caps center contact. Were there any running problems just before the failure? Perhaps a weird operation of the Tach? (a lagging behind or wildly swinging needle) Does the carbon trail inside the cap orient towards the cap vent?

[Bill Wallace]

Who manufactured the cap and rotor?

[Excaliber]

I'm guessing that's an MSD cap. Center carbon going bad is FAR TO COMMON on the MSD caps. It's been a problem for some time. I had one fail in a few thousand miles myself and right here on CC there have been other reports of the same.

This is not some "random event", MSD has a serious problem and frankly it pisses me off. I have to check my cap all the time now to make sure it's still OK and the those dang caps are not cheap. I'll be buying a different brand to replace it soon enough.

Frickin' recall if you ask me is what MSD needs to do, or at least own up to THEIR problem!

[Got the Bug]

Originally Posted by ERA Chas

The REAL lesson of the story is to NEVER leave the driveway with a leak of any kind-especially fuel. Have to be diligent about that to prevent this sort of thing.

Good advice! I always do a walk around the car, take a peak under the car, and open the hood and do a quick scan before taking off.

What are the other options to the MSD cap? I recall someone posting that Summit sold a replacement cap that was better quality and cheaper.

[mickmate]

Interesting we've increased the voltage, control and efficiency of our ignition systems alot over the years but we haven't found a better material than a spring loaded piece of carbon to conduct it all through a swivel contact??

[edwhite7]

I have had the same problem with my MSD, no fire though. After a few hundred miles I thought I had blown a head gasket, the car was undriveable. Attached is a pic of the inside of the cap. I also had huge problems with corrosion of the distributor that MSD replaced under warranty. The new distributor is no better and started to rust right away. I spent a lot of time on the MSD forum and the problem seems to be very wide spread in the FE series. I even cut the side of an old cap to check the alignment of the rotor. MSD's suggestion was to drill two half inch holes in the cap even though it is vented, instead I remove the cap when the car is not being driven.
Get on the MSD forum and do a search for rust or corrosion and see what you find, I gave up on them.
I think there is a thread on this forum also, I am pretty sure that I have posted these photos before.

[Rick Parker]

That looks like a Mallory Cap.

This particular cap does not have the significant series of ridges and vanes to prevent crossfire like many OEM caps and many of those from MSD do. Mallory caps are also generally shallower.

[patrickt]

Originally Posted by Rick Parker

That looks like a Mallory Cap.

This particular cap does not have the significant series of ridges and vanes to prevent crossfire like many OEM caps and many of those from MSD do. Mallory caps are also generally shallower.

Good eye, Rick. That is indeed the cap off of a Mallory dual point distributor.

[Ron61]

That was a mess but fortunately it wasn't as bad as it could have been. I check my distributor cap quite often as I to have had some misfires and it would be the center electrode starting to wear. I decided that since my car in no way resembled an original anyway to just change the distributor and I put in a Mallory magnetic one and it has been in there since 1998 with no problems. But I still check it along with all of the other connections pretty often.

Ron

[DougD]

Originally Posted by edwhite7

I have had the same problem with my MSD, no fire though. After a few hundred miles I thought I had blown a head gasket, the car was undriveable. Attached is a pic of the inside of the cap. I also had huge problems with corrosion of the distributor that MSD replaced under warranty. The new distributor is no better and started to rust right away. I spent a lot of time on the MSD forum and the problem seems to be very wide spread in the FE series. I even cut the side of an old cap to check the alignment of the rotor. MSD's suggestion was to drill two half inch holes in the cap even though it is vented, instead I remove the cap when the car is not being driven.
Get on the MSD forum and do a search for rust or corrosion and see what you find, I gave up on them.
I think there is a thread on this forum also, I am pretty sure that I have posted these photos before.

Where is all the moisture coming from?

Is this limited to FE applications?

What about the small block guys - are you seeing similar corrosion?

[CCX 33239]

Rick and Pat are right about it being a Mallory dual point. I have subsequently changed it to an electronic unit.
The car had been running flawlessly up until this startup. No misses, stumbling or anything and it had never backfired thru the carb before. I had worked on the carb the day before and didn't get one fitting completely tightened.....my screwup.
The rotor looked fine to me. No noticable damage or signs of arcing.

Bob

[RedBarchetta]

Originally Posted by Rick Parker

That looks like a Mallory Cap.

Originally Posted by DougD

Where is all the moisture coming from?

In pic #2 I see rust on other components ahead of the dizzy (neck to the expansion tank, etc.). I think there is something else here going on that is leading to excessive moisture beyond just the cap.

-Dean

[Double Venom]

NEW "MSD" cap!

At least the first time I had seen this, CptEddie has a new MSD system and we thought we had a bad cap??? The center contact 'normally spring loaded" was NOT, it was fixed! Now how they expect this to work when the carbon center starts to wear down I have no idea! (I have seen no difference on the FE's and the SB's.)

[Excaliber]

All though I personally haven't had corrosion or moisture problems I have heard about it across the board for all the various parts manufacturers, small block or large, no difference.

The primary solution does seem to be venting the dist cap, some of them come vented and so do not. If not, yeah, drill a hole or two in it.

I don't know if Mallory has a consistent center carbon problem, but MSD sure does!

[Blas]

I think it's actually the Ozone created from the small electrical discharges (arching) inside the cap that causes the corrosion. MSD now has a small capped vent (black) in most if not all of their caps. They also changed the cap material to something called Rinite I believe and made them red. Another interesting thing here too, the Rinite cap material seems to not block some of the energy emissions wavelengths generated inside the cap the way the older black caps did...Immediately upon replacing my older black distributer cap my Lasar radar detector went crazy...Put the old black one back on, all false alarms went away...put the new one on...crazy again.

[CJ428CJ]

Where is all the moisture coming from?

I don't think it's necessarily moisture that's causing all the rust although there is probably some moisture present. Any time you have arcing, you'll be creating ozone (O3). Ozone is very corrosive.

Chris

[edwhite7]

In pic #2 I see rust on other components ahead of the dizzy (neck to the expansion tank, etc.). I think there is something else here going on that is leading to excessive moisture beyond just the cap.

The other rust is local to those parts and lots of miles. MSD said the dist problem was due to an unvented cap and sent me a new center shaft and vented cap. These started to rust within a few weeks as can be seen in pic #1 with the cut away cap installed. They blame it on the MSD 6AL box with the hall effect ignition. They say it creates a large amount of Ozone that can't be vented through their vented cap. This is why they suggested that I drill additional holes in the cap. I think that the problem is made worse from the rotor being lower than the perimeter posts, seen in the cutaway. Does anybody else have dist shaft rusting problems?