Thread: What the hell happened inside my distributor? Pictures inside

Tweet

So I thought I had a carbuerator issue because the it didnt sound like a miss, and it drove fine at a higher RPM. Then I pull the distributor cap and find this. This is a Mallory 2092M distributor with vacuum advance.


So what I found was the center point underneath the where the coil wire comes in was completely burnt off, and the one side of the distributor cap has a giant gash in the side of it. Im guessing maybe an arc from a shorted wire? I have new wires that were just put on, and new plugs as well. Do you think it could have possibly taken anything else out in the ignition?

I need to add, when this problem started I found a plug wire had vibrated loose and was not connected to the plug. Upon pulling the wires i found the boots to be resting against the exhaust because they are incorrect wires, it could have possibly arced.

Im hoping this solves the issue. I had another post in the forum elsewhere but I took a break from the truck so that I didnt go spending money on something that wasnt an issue. Its good I did take that fresh look.

And the new one for reference.


So upon tracing the plug wire it leads right to where the gash in the side of the cap starts. So is this what burnt off that coil lead inside the cap as well? What all should I replace?

Cap was loose, or the rotor came apart?????

Cap was pretty tight and the rotor is as well, I don't think that this is an old mark. It's almost too much of a coincidence that the scorch mark starts right where the point is that leads out to the plug wire that came loose. I'm just hoping it didn't damage anything else

Are the shaft bearings still tight? If so, could just be from the bad wire, pretty radical for just that, though???

I'd start with a new cap & rotor to go with your new plugs & wires and see how it does with them. Wouldn't think anything else would be hurt.

Yea the shaft bearings seem tight, there definitely is not enough play for that to happen in my opinion. I do have a new cap and rotor along with the proper plugs and wires now. Thanks! I'll be checking up on the cap that's for sure. I think if the bearings were bad it would have destroyed that cap instead of just one spot.

So that short could just burn that coil lead inside the cap that bad? Someone told me its an infamous Chevy thing. I can't see how it's " a Chevy thing "

I've seen that from flashing when the plug cannot "fire".. I haven't seen it when a wire or plug has shorted. I'd replace the cap and rotor for sure!

Well the wire did basically come unhooked from the plug while driving so it really didn't fire it. Not sure if that's what ya mean by not being able to fire, or if your referring to a combustion problem.

i do not think it.s bearing ...looks like the cap was not flat with the dist body rotor knock it back ...on track .. thats the mark ... the center contack carbon was burn off when it first fired up cap off center .you can see the burn track .like to see the old rotor .. if this mallory has spring clips it just pop on .i seen were the fire wall is to close car moves alot of frame flex /engine movement on engine mounts under a hard load and will knock the cap off center or a wire gets clip under the cap and dist body see this to .with the flex deal two cars come to mine one i own

Hmmm ok so maybe this isn't my whole problem. As of right now the truck dies at idle, and can barely get it started. As I said though I first thought it was my carb. Guess I'll see, I was told to fix the ignition issue first and go from there. I should know by the end of the day today.

I'm guessing two different 'things' happened. One was a cap that was installed cockeyed and the rotor tip gouged the side of the cap.

The second was that arcing at the center electrode. I have seen this happen when the condenser was of the wrong capacity in the old point system, which I'm thinking you do not have and secondly, when the coil is reverse installed. Also, if there is a starting resistor that is supposed to be in the system and was either left out or gone bad. Then there is that old bugaboo - just one of those mysteries. Happens once and not a dang thing that happened before or ever will again

well maybe but carbon looks like it broke off ? two things did happen first was the cocked cap . funny the burn track is the same side as the rotor cut . burn mark may happen when the contack was missing open up the gap.then you had a arc welder in the cap as juice is not going to want to run threw the wires to fire plugs very good . it ran fine before this ?...... photo of old rotor would help .... if no resistor in line to drop the 12 volts frys the points in the mallorys points will not take it full time . i had a YL many years ago changed many points before i learned that resistor was bad and 12volts full time did not make them happy. that was 30years ago start at the ign side of switch track every thing down check with volt meter . try another coil . new point. condenser .new rotor . make sure cap is seated .air gap is righ on points i think .016to 018 gets close . plug gap is right 0.35. it should run fine

Originally Posted by 1923tbucket

Well the wire did basically come unhooked from the plug while driving so it really didn't fire it. Not sure if that's what ya mean by not being able to fire, or if your referring to a combustion problem.

Nope, that's what I mean. The electricity had nowhere to go so it found the easiest way to ground (or on it's way to it.)

You still need to replace some parts and as mentioned check voltages going into the ignition system. If it is battery voltage and it's a 12 volt system, you'll need a resistor to lower it in half. (or there abouts)..

Just a personal preference but, on a 6 volt ignition system, I like to set the plugs around .030".. small difference but I think it helps cold starting..

I agree with Pat those are mechanical related and not arcing. Distributer rubbing the fire wall is a good thought, any external marks on the outside of the cap you could have overlooked? Your sure the cap was on correctly, you said the unit itself is in good shape. I to would also like to see the rotor that would be a key shot to put up as Dave Severson pointed out. The button to me shows mechanical or rubbing damage looks like the collar it lives in is chipped . How about those contacts under the scratched area, anything going on there, can not tell from the angle of the photo what the condition of them could be.