Distributor cap burned?

[chaseincats]

Hi guys,

My distributor cap's center connector rubber bit seems to be melting courtesy of the HT wire from my spark coil.  Is this commonplace, or is there something going wrong here?  The car runs perfectly fine and only noticed this by chance...

Edited April 1, 2020 by chaseincats

[Patcon]

I would say a bad connection or corrosion is causing heat which is melting the cap

[chaseincats]

Are you thinking it would be a connection in that vicinity or just somewhere in the loom?

[Patcon]

54 minutes ago, chaseincats said:

Are you thinking it would be a connection in that vicinity or just somewhere in the loom?

I would think specifically that connection to the cap

[AK260]

I would say a bad connection or corrosion is causing heat which is melting the cap

+1 for this reasoning.

I also once found that happen when the boot and connector were not fully pushed home and it was arcing onto the cap/collecting moisture causing corrosion and resistance.

[SteveJ]

To elaborate on what @Patconsaid, if you don't have  the coil wire firmly seated against the contact in the distributor cap, you WILL have arcing between the wire and cap. This arcing will heat up a destroy the center post on the cap.

I actually got a $700 discount on my 260Z because of this. The owner planned on selling it for $3200 but knocked it down to $2500 because it wouldn't run. With a new cap and new plugs, it ran fine. He still sold it to me for $2500.

[chaseincats]

Thanks guys

I just checked and the majority of the terminals in the cap have at least some form of mild corrosion going on (but no melted terminals).  The cap and wires are only about 6 mo nths old - why are they corroding so quickly?

I have a tube of Ox-gard - should I just fill each terminal on the cap up with this and pop the connectors in?

Edited April 1, 2020 by chaseincats

[crayZlair]

Your cap probably has aluminum terminals, and you wires probably have some kind of plated steel terminals. Two dissimilar metals will eventually corrode due to electrolysis. The anti-ox will work, just don't use too much. (Better dizzy caps and wires will have brass-like terminals and not corrode as fast).

[chaseincats]

13 minutes ago, crayZlair said:

Your cap probably has aluminum terminals, and you wires probably have some kind of plated steel terminals. Two dissimilar metals will eventually corrode due to electrolysis. The anti-ox will work, just don't use too much. (Better dizzy caps and wires will have brass-like terminals and not corrode as fast).

You've probably hit the nail on the head - the terminals definitely aren't brass.  I'll put some of that goop in there and hopefully that will be the end of that.

Why would putting a non-trivial amount of that in each terminal be a bad thing btw?

[crayZlair]

5 minutes ago, chaseincats said:

 

Why would putting a non-trivial amount of that in each terminal be a bad thing btw?

The ant-ox is conductive. You want to keep the electrons from "spilling out" from underneath the rubber boot on the wires which could cause arcing, cross firing, etc.

[chaseincats]

2 hours ago, crayZlair said:

The ant-ox is conductive. You want to keep the electrons from "spilling out" from underneath the rubber boot on the wires which could cause arcing, cross firing, etc.

Gotcha - makes sense