[lookin]

My power connector, from the harness at the coil, keeps melting and falling apart. This is the second time this has happened. This second time with a new coil and new (to me) weather pack connector.

What is causing this?

 

[lookin]

Heavens sake. Over 20 people have read this, and no help for me?

Come on you guys.

Is it more likely that, the weather pack connectors are too sloppy and this allows a tiny bit of arcing, which degrades the connector as carbon traces slowly build up?

Should I just get another harness to coil connector, and then bend the little contacts inside toward each other, so they make a tighter fit on the coil connector post electrodes(?) .... .

How much dielectric grease do you guys usually put in there? Or is the cause something more serious I have no clue about?

Now please you guys. I need some help on this.

Give me a fnB here.

 

[Reaper1]

I honestly have never heard of this happening before. Two things I would check:

1: resistance from the connector to the SBEC and ground

2: primary resistance of the coil

Make sure both are in spec before doing it again. If they are in spec, then my guess is the same as yours. However, the only other thing that comes to mind is if you have the coil in the standard location for a 3.0 above the rear VC that it could just be getting that hot. It does get awfuly warm back there...so...maybe some sort of heat sheild? I've never seen this before as I said, but it couldn't hurt...

 

[jory]

I'm thinking the coil has too much resistance. Maybe try swapping it with a good one and a new connector, see if it happens again.

 

[lookin]

Thanks you guys.

I went through two brand new coils and power connectors already. The first was an MSD 8228, and the second is the Dodge version of that same MSD coil for Dodge 5.9L Dakota engines. It looks like the stock 3.0L coil. It has a male HEI output terminal though, and it is hotter .

Here is a picture of how it is mounted.

I also have the MSD 6A CD unit on there. Could that have anything to do with this? I don't see how it could. Maybe I broke a ground there or something.

I haven't got a clue, how to test for the 'resistance from the connector to the SBEC and ground', and I don't know what the spec on that is either.

I would be grateful for any more help you could offer.

PS

How much dielectric grease should I put into the connector? Tiny bit? Pack it full to the brim? Or what?

 

[roguetrip]

pics would help.

Your talking about the connector with 2 prongs that go to the engine harness are melting the plug or the wires?

If its melting the wires the coil could have lower resistance on the primary coil (since this not the stock coil) which is higher amperage than what the wires are rated for. Maybe your wire splice used too small of wire?

The more dielectric grease the better, just make sure the plug can stay on, if anything squeezes out just wipe it away.

 

[Reaper1]

Crap....you have an MSD. I honestly don't know how it's hooked up, so I don't know how to tell you to test it.

 

[turbokid]

we melted a coil connector on my dads 69 roadrunner with an arcing spark plug wire.

 

[lookin]

pics would help.

Your talking about the connector with 2 prongs that go to the engine harness are melting the plug or the wires?

It's melting the plastic plug case, inside where the contacts are, and not the wire. So now I really think the plug contacts were just sloppy, and I didn't use enough dielectric grease.

Thanks roguetrip, and thank you also Reaper1.



turbokid

That's a good reminder. I really should check all my plug wires too. Thanks.

 

[crazymadbastard]

The 92 fsm lists bad spark pluc-coil to dizzy wire as possible causes of damaged coils.

 

[lookin]

Thanks crazymadbastard. I better get to cutting that new set of MSD 8.5 wires I got a couple of months ago.

 

[c2xejk]

Picture of the melted connector?

 

[lookin]

It is barely noticeable, and so a picture wont show much. I caught it early. Been keeping an eye on it since last time. I will take one when it clears up weather wise though.

 

[c2xejk]

I did some reading last night and I think I understand the problem... You have an MSD6a and a higher energy coil. The MSD (at low RPM) creates multiple sparks. It does this by pumping up the voltage to the coil (via the capacitor discharge.) This is done to quickly saturate the coil (shorten the dwell time needed.) This means more current (peak) will be flowing than normal and more often (multiple discharges.)

With a conventional setup you would have 3 plug firings engine revolution. With the MSD it is fire some multiple of that. Thus there is no time for the wire to cool back down before the next firing.

Combine that with the high energy coil that also draws more current to create a hotter spark. The result is you are melting the wires because they are carrying more current than they are rated for...

You can try:
-thicker wiring and better connectors
-ditch the performance coil
-ditch the MSD6a
-find some way to provide more cooling

 

[Reaper1]

While I agree with the theory stated above, I don't see this melting the connector because we are only talking probably a maximum of 300 milliamps at 12V. The capacitor does not step up voltage, that's not its job. It only stores energy. The capacitor allows there to be multiple discharges becuase it stored enough energy to quickly saturate the coil during that VERY short amount of time.

I DO agree that the coil itself may get hot enough to melt it though....

 

[c2xejk]

How can the coil be saturated any faster without raising the voltage? The stock setup sends in battery voltage. How is the capacitor saturating it faster?

Regardless, if you are firing the plugs more times/cylinder event, you are pumping more current in. More current-> more heat...

 

[kermit]

V=I*R. Voltage could stay the same if current is increasing and there is less resistance in the coil. You need bigger wires that can handle more current.

 

[lookin]

The result is you are melting the wires because they are carrying more current than they are rated for...

I really appreciate you getting involved and helping Ed. Just to be clear though. The harness wires, leading to the connector, are not melting. They aren't even heating up that I have noticed.

The female pin contacts inside the harness coil connector, that the male coil pins slide into, are what is heating up. Then they very slowly melt that plastic harness plug they are inside of.

(A)
|| <- the two male pins on the coil itself

(B)
UU < the two female harness plug pin contacts


So my theory is this.

The female pin contacts were a bit sloppy, leaving some airspace between them and the male coil pins, which allowed some arcing to take place and generate heat.

This heat generation, slowly increases over time, because carbon builds up at the arcing points and decreases current resistance. The lowered resistance then increases the arcing, that degraded the metal pin contact, part of which fell out of the connector upon my inspection of it. .

Is any of that right? Or have I made some wrong assumptions here?

On Edit: ( Clarified the stuff in red, and added forgotten detail about part of the metal contact falling out)

Maybe I can compensate for that, by getting a new harness coil connector and bending the female pin contacts together a bit more, so they fit tighter on the male coil pins, and the arcing will not happen anymore?

Man I am way outa my league here.

Please help.

 

[lookin]

While I agree with the theory stated above, I don't see this melting the connector because we are only talking probably a maximum of 300 milliamps at 12V. The capacitor does not step up voltage, that's not its job. It only stores energy. The capacitor allows there to be multiple discharges becuase it stored enough energy to quickly saturate the coil during that VERY short amount of time.

I DO agree that the coil itself may get hot enough to melt it though....

You are right about what the MSD 6A does Reaper, and MSD doesn't recommend upgrading the harness wires, or the connector itself, when installing their 6A CD unit.

On Edit: ( MSD does say you need a hotter coil with it though.)

Please, take a look at my last post, and tell me if you think my theory is right.

 

[lookin]

With a conventional setup you would have 3 plug firings engine revolution. With the MSD it is fire some multiple of that. Thus there is no time for the wire to cool back down before the next firing.

That sounds very plausible.