Greased Lightning
 

Dudes and dudettes: Does silicon grease conduct electricity? In my local parts store they have tiny tubes of "dielectric grease" which I think may be repackaged silicon grease. Like Dow Corning 111. Is it an conductor, or an insulator?

Its an insulator - dielectric means that it provides higher insulating properties than the reference, which is air. This grease is not formulated as a lubricant - better to use a specific silicone lubricating grease, unless you need the dielectric properties.

So what is the purpose of dialectic grease/what does it do? Isn't this the stuff that one puts on the distributer cam on a points car? TIA. :cool:

dielectric grease is used at least in computers to provide good thermal contact between hot CPU's and the heatsink. I'm not really sure what it's used for in the automotive sense.

A lil dab will do ya

Put a little dab in the spark plug boots, and under the dist boots. The grease wont let the rubber bond with the porcelain or bakelite

i.e. easier to remover plug wires etc.

The <b><i>'ORIGINAL' silicone grease,</i> Dow Corning 4,</b> was developed for use in military aircraft electrical systems around the end of World War II ... it is intended to fill the void around connectors and prevent intrusion of air [Oxygen source] and water or water vapor ... hence, protect against corrosion!

See:

http://forums.pelicanparts.com/showthread.php?s=&threadid=53669&highlight=dielect ric+grease

Thanks, all! I recently had starter trouble that was caused by a poor connection in one of those big rectangular plugs in the engine compartment. So, to avoid a repeat I am considering cleaning and coating those electrical connections. I'm still the 5-year-old who always has to ask "why?"

Dielectric is useful where zener diodes and the like need solid bonding as well for heat sink ability. I use this on Brit bikes that need to bleed off heat to a heat sink.

NAPA seems to sell the best silicon grease though. That stuff is the ticket wherever you must grease a rubber item that would degrade from the caustic/corrosive nature of petroleum-based greases.

Great question.

John

Four Wheelin'
 

I have used it to seal ignition connections on both my truck and car.

Main reasons I use it is to seal out moisture (good for dunking the truck, good for washing the car...). I put a small amount around the spark plug boots, distributor cap seal, anywhere I don't want water to get in.

Works great.

Gordo

Umm, maybe some confusion here:

Silicone grease, which is an insulator [ie has dielectric properties] is the ticket for corrosion protection. Its the familiar clearish stuff that is related by birth to Dow Corning 4.

Silicone heat sink grease is another animal - silicone modified with magnesium powders [and other stuff] to help it conduct heat from semiconductor components [power transistors, diodes etc] to a metal heatsink. Its usually white, and might be the messiest spooge ever to deal with. Don't use this stuff for regular water sealing and anti-corrosion applications. You won't find it in an auto parts store.

Actually our local NAPA has the "loaded" heat sink silicone compund in stock as it is used to "heat sink" various replaceable electronic assemblies used in cars. The "spooge" was used in both my '85 GM vehicles. Jim

Never underestimate NAPA. My bad.
Thanks Jim - I should have been more circumspect.

Re: Four Wheelin'
 

yep.. I use silicone bearing grease that sticks like bubble gum around marine engine compartments.. good stuff............Ron

The best heatsink compound is made by Wakefield.
It's white...sticky...and just nasty to get off your hands....seems to stick forever.
In the case of connections....make sure thet are clean....then coat them with Stabline 22 (expensive but worth it)...then connect...then coat the outside with your choice of silicone grease.
This way the connection is good...and the corrosion is held on the outside.
Bob

The instructions I've seen has been to coat the plug boots to prevent arcing, and that when the other parts (like the spring loaded tab over the rotor) are pressed together they push the grease out of the way to ensure contact.

Still, a non-conductive film doesn't sound right, and the grease doesn't flow into the tight areas. Would WD-40 work better for wire connections?

Jim, I had same starter problem with 14 pin connector in engine compartment. Cleaned connections and packed with dielectric silicon. No problems since. Also spread the male contacts on connector with an exacto knife to tighten the connections.

Hey Bob..
I've been using the electric store grey anti-corrosion grease.. are you talking about the same kind of stuff?..............Ron