Improper Use of Dielectric Grease?

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Model T Ford Forum: Forum 2014: Improper Use of Dielectric Grease?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Thursday, April 17, 2014 - 12:53 pm:

Hello all, I am trying to track down an intermittent (but getting increasingly worse) ignition misfire on my 1923 touring/pickup conversion (no magneto, currently running a Truefire unit on 6V). I have pulled the coil box out of the car and pulled the Truefire unit out of the box. I noticed that the previous owner had slathered dielectric grease on all the internal coil box contacts, and on several of the contacts there was a black residue mixed in with the grease.

Is this an appropriate use for dielectric grease? I have read elsewhere online that arcing can cause the grease to break down.

While I have the coil box out I am going to install a Fun Projects wood replacement kit and new bronze contact strips. My terminal bolts and ceramic insulators are fairly new (the previous owner replaced them in 2008). Currently, I do not intend to re-apply any dielectric grease.

Any other testimonials for/against dielectric grease?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Thursday, April 17, 2014 - 01:11 pm:

As a professional amateur, here's my $.02 worth:

I always thought the purpose of dielectric grease was to seal moisture out of electrical connections. Therefore, I believe using it as you describe would, over time, actually interfere with connections made by "spring force", like those in a coil box. That's probably why you're seeing black residue, caused by arcing which scorched the dielectric grease.

Perhaps a better choice would be conductive grease, but I'd recommend against that too. Eventually, I imagine it would short things out since it is a liquid conductor and could travel around a little.

In my humble opinion the best thing to use in the coil box is nothing, just good, tight, and clean contacts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By G.R.Cheshire on Thursday, April 17, 2014 - 01:13 pm:

Mark I would think Di-Electric grease is great in areas where the contacts are prone to be contaminated with moisture or oils that could cause problems such as the quick disconnect going from the engine compartment to the passenger compartment in modern cars and tail light assemblies. But in a protected area like the coil box I don't see the purpose.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Vancouver, WA on Thursday, April 17, 2014 - 01:38 pm:

I can't imagine the dielctric grease is the problem. It may not be doing much good, but I wouldn't think it is the issue. I do bet the issue will be resolved after you rebuild that box with the F.P. kit (REALLY recommend the non-wood version) as all connections will be new and clean with no carbon tracking in any of the wood.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan B on Thursday, April 17, 2014 - 02:26 pm:

Dielectric grease is good for eliminating problems due to leakage current. This is why it is often used on spark plug terminals before installing spark plug boots. It relies on enough of the grease being displaced during the mechanical connection so that an electrical connection can be made.

Like any grease, it will prevent oxidation of what it is applied to. Again, the advantage here is that it is non-conductive.

All that said, I do not see any advantages to using it in the coil box. I would not reapply it after you rebuild it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Thursday, April 17, 2014 - 03:17 pm:

Thanks for the input, I wasn't suggesting that the dielectric grease was the cause of my problem, just looking for input on whether to re-apply it or not.

I will not be using it in the re-built coil box.

Thanks again! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Thursday, April 17, 2014 - 03:35 pm:

Dielectric Grease should not be used on contacts. A Conductive Electrical Grease would be better to make a good connection and prevent corrosion.
Something like:
http://www.landscapelightingworld.com/Conductive-Electrical-Grease-p/9elecgrease .htm?gclid=CMqWjr2h6L0CFQqEfgoddRoASw&utm_source=google&utm_medium=cpc_feed&utm_ campaign=comparison_shopping_feeds

Jim


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