C2 Bulkhead connector: apply dielectric grease or not?

[Gary B.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

Phil,

Your multimeter test might have had the probes too far apart. Maybe the conductive paste is conductive on the micro-asperity scale, as in the image that Joe posted.

Gary

[Phillip M.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

Phil,

Your multimeter test might have had the probes too far apart. Maybe the conductive paste is conductive on the micro-asperity scale, as in the image that Joe posted.

Gary

Gary,
Yes, I believe that is the case. I have two auto-ranging multimeters where the probe resistance reading is between 0.4 to 0.6 ohms (dry, cleaned probes touching each other). With a generous coating of Kopr-Shield applied, I can actually rest one probe on the other with their own weight as the force and get no reading. When I apply more force to the probes I will get the expected reading of 0.5 ohms. Both multimeters show the same results.
Phil

[Gary B.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

[Mike T.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

I've been working on my 65 NOM L78 Roadster since it got here in late 2019 and when I pulled the engine and light harness connectors away from the firewall, I found one of the fuse box terminals had moved back a bit. Went inside to pull the fuse box apart and along with resetting the tangs on all the connectors, I noticed some corrosion on various metal parts inside the fuse box which wasn't much of a surprise due to this Roadster having been originally sold in Portland Oregon and had spent nearly it's total life in that area. I cleaned and wire brushed all the connectors inside the fuse box and wanted to apply some sort of coating to prevent further corrosion, not that it was totally necessary since I live in North Central Arizona and yesterdays humidity was only 11 percent but did some looking around for something other than di-electric grease and found a product called NO-OX-ID made by Sanchem Inc. It's a thick dark brown grease that comes in a small plastic tub with a couple small acid brushes and the manufacturer's website says:
NO-OX-ID electrical contact lubricant (electrical contact grease) is an electrically conductive grease that keeps metals free from rust and corrosion.
Mike T - Prescott AZ

[Gary B.]

Falicy of adding metals to increase conductivity:

Many electrical contact greases have copper, zinc or other metals blended into a grease to increase conductivity. In a study for an aerospace company in 1985 it was concluded that putting metal into grease does not help conductivity. In many cases it reduces conductivity. The United States Department of the Interior Bureau of Reclamation states in their Facilities instruction Journal Volume 3-3 Electrical Connections for Power Circuits

[John D.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

Here's some info from the current GM service procedures on the use of dielectric grease:


Testing for Terminal Fretting

Some intermittent conditions can be caused by wire terminal fretting corrosion. Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is a small motion between electrical contacts. The oxidized wear debris can pile up enough at the electrical contact spots that the electrical resistance across the connection increases. Movement between the contacting surfaces as small as 10 to 100 microns can cause fretting. To put this in perspective, a sheet of paper is about 100 microns thick, so fretting motion is small and hard to see. Vibration and thermal expansion/contraction are the main sources that create fretting motion. Since vehicles vibrate and can experience large temperature swings, they are a good source for fretting motion. Tin, copper, nickel, and iron surfaces are all susceptible to fretting corrosion. Fretting corrosion can be difficult to see but it looks like small, dark smudges on the terminals contact surface.
To correct a fretting condition disconnect the suspect connector and add dielectric grease / lubricant (Nyogel 760G or equivalent, meeting GM specification 9986087) to both sides of the connector terminals. Then reconnect the connector and wipe away any excess lubricant. This will correct the additional terminal contact resistance due to the terminal fretting corrosion.

[Mark H.]

https://www.corrosionx.com/collectio...30930717966432

[Phillip M.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

Open circuit, no conductivity. So far, I have no complaints in using this product for about 4 years for the intended purposes mentioned in this thread. Are there better products intended strictly to improve conduction? Yes, definitely. Several years ago I was doing some research for one of my company's products on conductive coatings to dissipate electrostatic discharges. One product that proved 100% reliable was a conductive grease containing a high loading of silver particles. However, I had to rule it out due to (high), cost. As I recall it was sold by the gram (something like $10/gram - do the math!).
Phil

[Joe R.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

A few facts!

The military has been using silicone dielectric since the fifty's!

It is used to keep the moisture from the connectors and nothing else. It protects the contacts from oxidizing and therefore allows the connectors to conduct the signal!
Using it would be advised after the connectors are new or have been cleaned.

JR

[Gary B.]

[Joe R.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

The purpose of the grease (any grease) is to inhibit corrosion! The military studied this very carefully years ago and still use the dielectric to keep million dollar aircraft in the air! Good enough for me and some cheap Corvettes! At least cheap compared to multi million dollar aircraft!

JR

[Duke W.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

A few facts!

The military has been using silicone dielectric since the fifty's!

It is used to keep the moisture from the connectors and nothing else. It protects the contacts from oxidizing and therefore allows the connectors to conduct the signal!
Using it would be advised after the connectors are new or have been cleaned.

JR

As with oil changes and many other maintenance issues we need to consider the type of service when deciding how to maintain electrical connectors. Clearly vintage car service is much less severe than a military vehicle, so military practice is not necessarily a model.

Since my current modest fleet (all bought new by me) contains cars ranging from 30 to 58 years old, I have some experience with electrical connector problems. The first was with my SWC when the TI (that I installed from the '67 12-mile L-88) failed circa 1976. This was the second failure that turned out to be simple exfoliation corrosion in the amp connector, but by that time I was fed up with the TI and had figured out how to make the single point distributor work flawlessly to 7000 revs, so I removed the TI system, cleaned off the corrosion, bench tested the system as good, and put it in a box until I sold it to David Burroghs in 1988 when he owned that L-88.

In the mid nineties my Cosworth Vega began occasionally exhibiting intermittent "gliches" like the ignition or fuel was cut off for a fraction of a second. The Bendix/Bosch D-Jetronic EFI system has dozens of low voltage (as little as 5V) connections with very small connectors. I decided to remove each one, carefully inspect with a magnifying glass, and scrape off any corrosion with a dental currette. Then I gave each one a shot of electrical contact cleaner and when that dried a quick shot of WD-40. It probably took a couple of hours and I didn't find anything obvious, but that "glich" never reoccured.

I knew from experience that WD-40 leaves a long lasting film that is excellent at repelling water, and since the car was not driven in the rain and rarely if ever even exposed to condensing humidity, the WD-40 would be more than adequate. It wasn't going to be driven by a grunt through a swamp.

The other problem I have with packing electrical connectors with any kind of grease it that it makes a bloody mess.

As far as conductive grease is concerned I wouldn't pack a multipin connector with that stuff because it could cause shorts between the various circuits.

So if you think your service is severe enough that you need to pack connectors with grease, that's your choice, but in my experience, a film of WD-40 is more than adequate to provide decades of electrical connector corrosion protection for the light duty service that most vintage cars see.

Duke

[Larry M.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

CRC makes an electrical protectant and lubricant called #2-26. I have used it over 30-40 years on various electrical connectors in house and car for protection. It would offer similar protection to WD40, but perhaps is a bit better or more suited for electrical.

FWIW.

Larry

EDIT: https://www.ideadigitalcontent.com/f...RSPE/45338.pdf

[William F.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

You wouldn't wnat anything with copper in it to possibly accidentially go across 2 or more connections. This would cause shorting. I'd be afraif to use Kopr-Shield on bulkhead conectors.

[John P.]

Re: C2 Bulkhead connector: apply dielectric grease or not?

Another consideration would be the use of DeOxit-sprayed onto the connectors. Works well in stereo connection issues- I have removed the corrosion manually with tiny file to bare metal added the DeOxit. It is quite thin, dry easy to apply