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There's a lot of chatter about the use of dielectric grease.  Permatex suggests that Dielectric Tune-Up Grease is a good barrier to oxidation at plugs, connectors and terminals.  There are some online comments at forums that say not to place dielectric grease on connector pins. 

 

I've gone to the Permatex site, and the information is vague: 

 

"Protects electrical connections and wiring from salt, dirt and corrosion. Extends the life of bulb sockets. Prevents voltage leakage around any electrical connection. Also prevents spark plugs from fusing to boots. Required for modern high energy ignition systems."

 

Another quote from the Permatex site:

 

Directions for Connectors: 1. Make sure ignition system is off. 2. Clean surface with Permatex® Contact Cleaner. 3. Coat both parts of terminal contact with Dielectric Grease. 4. Reassemble, maintaining metal-to-metal contact. - See more at: http://www.permatex....h.mSLOFJcy.dpuf

 

Also, here's the PDF product information download from Permatex:  pdf.gif  Permatex Dielectric Tune-Up Grease PDF.pdf   69.55KB   0 downloads

 

In the PDF, Permatex cites uses for the Permatex Dielectric Tune-Up Grease:

 

TYPICAL APPLICATIONS

• Spark plug boots

• Distributor cap nipples

• Battery terminals

• Ignition coil connectors

• Headlamp connectors

• Trailer electrical connectors

 

The "metal-to-metal contact" reference may create suspicion for some about "Dielectric Tune-Up Grease".  I've used this product for years around tune-up work without reservation.  I searched around and found an engineer's assessment of dielectric grease that suggests Permatex Dielectric Tune-Up Grease should work well on a variety of pin connector materials without creating any kind of resistance or barrier to current flow.  This commentary is worth reading: http://www.w8ji.com/...tive_grease.htm, the author seems well informed, experienced, and he uses a scientific approach.  According to the engineer, metal-to-metal pin contact should result if pins are clean and not tarnished, with or without dielectric grease on the pins. 

 

It's realistic to presume that the degree of conductivity is governed by the tension of the pin and socket fit, not whether we use dielectric grease.  Whether or not you use the dielectric grease, I would use a quality electrical contact cleaner to get rid of the oozing material at your PCM plug and terminals.  Make sure you flush out all residue and allow complete evaporation to prevent dilution of remaining grease or any issues with spark arc hazards.  I would at least place dielectric grease on connector lips to act as an effective moisture and oxidation barrier.  

 

Personally, I'm good with the use of dielectric grease, others can use their own judgment.  For me, the engineer at the www.w8ji.com site confirms and clarifies its intended uses.

 

Moses

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Moses, im not sure how much of a difference it makes in the dryer areas out west, and even some parts of the southern states, but, in the northeast, dielectric grease is pretty much a have to have item if you want to keep corrosion out of electrical connections. As you know, i work on a lot of imports, Subaru being the main one, and some of the electrical connections are underneath the rear, especially evap canisters, and if those connections, as well as almost every electrical connection there is, arent coated in dieelectric grease, after they are properly cleaned, they will rot and cause all kinds of issues. Another reason i have found to use it though, fits very well here. Quite a few people in my area have off road, lifted, purpose built mud trucks, and i have seen many times where things like exterior lights, horns, and even misfires can occur after running a truck in mud, simply because the connections werent greased well enough, or not at all.

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Good points, one and all, Biggman! There's a lot of controversy online about the use of dielectric grease. My most recent encounter with a supportive reference was the test of the Enerpulse Pulstar® spark plugs, which was publicized at the magazine and posted at the forums.

 

Enerpulse emphasizes the use of dielectric grease on the terminal end of the spark plug. This is clearly a conductive and critical part of the plug. I also add dielectric grease to the insulator between the shell and terminal to create a moisture barrier for the spark cable boot.

Thanks for sharing your experience here...Always great to see your posts!

Moses
 

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I'll just add that in my over decade of modifying military aircraft with new electrical systems we never used any form of "electrical" grease on any connectors. Now that doesn't quite relate to Jeeps in the context of the thread. Nor is that to say you shouldn't use corrosion control type purpose greases with electrical connections. I am sure it has its place and I even use them in areas that I know will create an environment of corrosion. BUT, and my big but is to look into connector styles, and placement. All connectors in aviation that are critical and can be exposed to weather elements are designed to prevent that and equally in a aircraft you will have connectors that have no protections at all. This same mentality is evident in modern vehicle design. I am sure we all have come across those pain in the butt connectors that seem to be over engineered, but really they are not. If you know anything about cost benefit per cost per unit you will know it is mostly taken into account. This may not be true with aftermarket products or your own personal modifications. So keep metallic similarity (disimilar metals love to interact), connector seals and placement into account when working on or adding electrical systems to your Jeep. 

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Did my spark plug connectors and distributor on my 97 Volvo and its all good. Still unsure of the connectors associated with trailers or other multi-pin configurations as I have read that the grease could allow electrical transfer between pins, which in my limited experience sounds like a potential short, witch would suck.

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I use dielectric grease sparingly.  You bring up a good point, and this could be tested with a sensitive volt-ohmmeter.  On non-weather tight plug connectors, with face-to-face connections and no seal around the joining points (like the common flat 4 or 7-pin trailer connectors), road debris is often conductive

OEMs often use dielectric grease on the pins inside weather-tight connectors.  These kinds of sealed connections seldom give trouble:

  150 Series Metri-Pack

I could see an issue with trailer connections (like the example below), though the issue could be conductive debris and not the dielectric grease itself.  Again, this could be tested with a quality volt-ohmmeter.

Although Permatex actually recommends its Permatex Dielectric Tune-Up Grease for trailer connectors (see excerpt from the Permatex PDF above), I do not use dielectric grease on trailer connectors.  Most often these connections are only temporary.  I do, however, make sure that contacts and pins are clean and free of debris and corrosion:

Reese Towpower 74682 - Reese Towpower Vehicle Towing Wiring Harness Connectors

Has anyone had an actual experience with voltage leaks and dielectric grease on trailer plug connectors or anywhere else?  Please share your findings...

Moses 

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