Topic: Spark arcing from spark plug cap

[papi_sosaa]

These new caps never touched the old plugs. There is no grease on any of these parts.

[scottly]

I'm sorry, I can't offer any more than what I already have. Please let us know when you find a fix for your problem.

[papi_sosaa]

Just out of curiosity, why no dielectric grease?

It's a common practice to apply some to the sides of the spark plug cap/boot as it's non conductive and acts like an insulator, wouldn't that be a good thing?

[Deltarider]

I'm curious. This dielectric grease... (I don't even know the Dutch word for it). I have never heard of any mechanic here using it and personally I never needed it. What good is it and what are the no-no's?

[newday777]

No, there's no grease on the plugs or inside the caps at this moment.

Are you sure about that? The use of grease is a smoking gun for your quite unusual problem. I was wondering about it before, but since the problem then only involved the one cylinder I dismissed it. Now the problem has moved to two other cylinders, and the common denominator is the grease.

New plugs, new coils, new cords, new caps. No grease was applied yet and now, never will be.

Were the old coils and caps also from 4Into1?

[papi_sosaa]

No, there's no grease on the plugs or inside the caps at this moment.

Are you sure about that? The use of grease is a smoking gun for your quite unusual problem. I was wondering about it before, but since the problem then only involved the one cylinder I dismissed it. Now the problem has moved to two other cylinders, and the common denominator is the grease.

New plugs, new coils, new cords, new caps. No grease was applied yet and now, never will be.

Were the old coils and caps also from 4Into1?

So originally....

Caps, HT cords, and coils were OEM. Then I noticed the arcing on #4.

Cap #4 was broken and the rubber boots on either side of the #1 caps were cracking so I replaced caps #1 and #4 with resistor caps from Vintage750. Cap #4 was still arcing.

Now, I replaced all caps, HT cords, coils, and spark plugs (No grease!). Based off the condition of the electrode on the old spark plugs, the engine has been operating fine. Cap #4 looks fine but now #2 and #3 is arcing. I measured the Ohms of the caps and spark plugs and the range was between 4.7K Ohms to 5.3K Ohms.

When I have a chance, I'm going to take it all apart again, re-measure all my Ohms and then report back.

I'm curious. This dielectric grease... (I don't even know the Dutch word for it). I have never heard of any mechanic here using it and personally I never needed it. What good is it and what are the no-no's?

The point of the dielectric grease is to help keep water away from the spark plug. It's also supposed to make it easier to remove the cap from the spark plug. You're not supposed to put grease onto the spark plug terminal as the grease also acts as an insulator and can cause another set of issues. You're only supposed to apply a thin layer of grease to the cap boot so that it applies it to the ceramic section when you slot it onto the spark plug.

[MauiK3]

What about your engine block ground? Could it be affecting this?

[scottly]

Just out of curiosity, why no dielectric grease?

What is the dielectric (insulating) rating of the grease you used? The ignition system puts out thousands of volts.

[papi_sosaa]

What about your engine block ground? Could it be affecting this?

In this situation, no.

Just out of curiosity, why no dielectric grease?

What is the dielectric (insulating) rating of the grease you used? The ignition system puts out thousands of volts.

Not sure what its rating is but the primary purpose of dielectric grease is to prevent moisture and corrosion from reaching the electrical contact(s) that it is protecting. Dielectric means insulating or non-conductivity. It's supposed to prevent arcing without interfering with electrical current if applied correctly.

One of the biggest uses of dielectric grease is for spark plugs.

I have a suspicion that I might not be screwing these HT cords in as far as I think I am and it could be causing extra resistance that is leading to the arcing. The broken OEM cap was one thing but this is obviously something else that is a symptom to that fault. This is why I'm going to measure the HT cords and caps separately and then measure them once they're connected.

I think I'm also going to put the OEM coils back in. I don't like how the contacts in the coils from 4into1 also screw into the HT cords like the caps do. The OEM coils have like a nail or spike that the HT cord just presses onto.

[Don R]

 It sounds like plenty of spark is getting to the plug, it's enough to overcome the plug caps somehow. I wish I was close, I'd love to see it myself.

[scottly]

Are the 4into1 caps NGK brand?

[papi_sosaa]

Are the 4into1 caps NGK brand?

No, they're some Chinese knockoffs. I believe the NGK resistor caps are discontinued.

[Don R]

 When the plug caps go on, can you feel the threads on the sparks plug engage the springy latch in the inside of the caps?

[papi_sosaa]

When the plug caps go on, can you feel the threads on the sparks plug engage the springy latch in the inside of the caps?

Yeah it feels pretty solid going on. Even taking them off takes a bit of force.

[scottly]

What was the brand of the grease?

[papi_sosaa]

Permatex Dielectric Grease.
https://www.amazon.ca/Permatex-22066-Dielectric-Tune-up-Grease/dp/B07NQP339F?th=1

[dave500]

ngk resistor caps are still available.

[bryanj]

If you can find them Dave, apparently NGK have stopped making them

[dave500]

I see lots available here in Australia from many places,I guess until stocks last?

[MauiK3]

Something doesn't add up. Good caps, wires, coils and yet spark still gets out. Maybe something in the wire itself? Has to be a "leak point" somewhere.