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Thread: Should I use dielectric grease on cap, rotor, & plugs?

  1. #1

    Default Should I use dielectric grease on cap, rotor, & plugs?

    I thought dielectric grease was an insulator, but the hanes manual I have says to put some on the inside terminals of the distributor cap when I replace it. And, I thought I read somewhere to use it on the plugs and cap terminals where the wires connect. Search didn't come up with much. What should I do? I understand it helps prevent corrosion, but wouldn't this insulating grease decrease the current flow?

    Thanks.
    1998 Jeep Grand Cherokee TSI

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    It is an insulator (dielectric). Its main purpose is to help the rubber caps slip off easier. You could put it on the contact and still have spark through the remaining metal-to-metal, but the only benefit would be to keep out water. Toss-up, and I suggest not.

    I wouldn't put any stock in Haynes, regardless.

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    Registered Jim Hef's Avatar
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    It's a good grease for keeping moisture out, and it makes disassembling easier in the future. Smear it on the inside of the spark plug boots, and around the lip of the distributor cap.

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    HEY LOOK AT ME!! BobKWJ's Avatar
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    To answer your question, do not use it on the metal to metal electrical connections. It will inhibit the conductivity of the connection.
    If you're not living on the edge...
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  5. #5

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    Quote Originally Posted by BobKWJ
    To answer your question, do not use it on the metal to metal electrical connections. It will inhibit the conductivity of the connection.
    That's what I wanted to know....Thank you.
    1998 Jeep Grand Cherokee TSI

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    Registered oldgeezer's Avatar
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    It can be useful in preventing moisture and air and other corrosive stuff away from the uninsulated metal (blades, pins, sockets, etc.) in metal-to-metal contacts of separable electrical connectors. When the connectors are pushed together, the metal-to-metal contact is made by the blades, pins, etc. pushing the soft grease away from the areas of contact.

    I differ from BobKWJ and will say that the grease will not hinder electrical conduction in a metal-to-metal contact any more that any other insulator, like air or plastic if the contact is potted, surrounding the contact.

    However, in a distributor, the rotor does not actually come in physical contact with the electrodes in the cap. There is a very small gap between them. Grease on the rotor tip and the electrodes could fill up the gap and make it a little harder for current to jump that gap. Current through the grease could also cause chemical reactions that would degrade the tip of the rotor and the electrodes. Don't use dielectric grease in those places.
    2001 WJ Limited, 4.7L, Quadra-Drive -- Kenne Bell Supercharger, Stillen Rotors with MM pads (F/R), Addcos (F/R), Kolak 3 inch exhaust with large case MagnaFlow, Rogue Chrome wheels, DRL activated, and Blaupunkt 3.5" dash speakers.

  7. #7

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    I use it on all of my engine electricals.

    Sam

  8. #8

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    Well, since it doesn't seem to be absolutely necessary, I'm not going to use it.
    1998 Jeep Grand Cherokee TSI

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    Registered Taggart's Avatar
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    I agree with oldgeezer's write-up, and used to use dielectric grease in spark plug wire boots and around the lip of the distributor cap to keep out moisture when I had that type of ignition. Now, the only place I use it is to coat the battery terminals and cable clamps to help prevent corrosion.

  10. #10
    HEY LOOK AT ME!! BobKWJ's Avatar
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    If everyone had agreed on the use of dielectric grease in this thread it would have made JU history! Like every other topic I've seen here there are at least three differing opinions.
    I was advised by my friend who is a biotech engineer. He services and repairs ll the electrical equipment in the hospital. If I'm going to trust my life with his work I'm going to trust my Jeep with his advice. Applying DG to electrical connections will probably not noticably decrease performance. The proper use is to seal moisture away from the connection. If you are having significant corrosion issues DG on the connection may be a good idea, also on connections that slide against each other like potentiometers. Bottom line it's probably not necessary to apply to the connection and will inhibit the conductivity more than it will enhance it. That's my story and I'm sticking to it!
    If you're not living on the edge...
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    A dielectric is not an insulator, it's only a partial insulator. IOW, it acts as an insulator up to the breakdown voltage, at which point it will conduct.

    It will not affect the metal terminals since these will be in contact with each other. If they weren't, the grease would be the least of your worries. The purpose of the grease, as previsouly stated, is twofold: One is to keep moisture away from the connections (moisture, or condensate, is also a dielectric, only with a much lower breakdown voltage, obviously) to prevent corrosion and the like, plus it prevents or at least reduces the likelyhood of plug boots from seizing the plug. This is something you'll be grateful for later...

    In short, use it.
    Doug

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  12. #12

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    Interesting.....I didn't realize there would be such differing opinions. Seems like a good idea to use it on the inside of the rubber boots but not on the metal itself.
    1998 Jeep Grand Cherokee TSI

  13. #13
    muchacho largo longboy's Avatar
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    Ever check out what the manufacturer says about it?

    http://www.permatex.com/products/pro...&item_no=22058

    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.

    Suggested Applications:
    Marine and automotive electrical connections, spark plug boots, trailer hitches, battery terminals


    Use it.
    2006 WK 5.7 Hemi

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    the logical one fixer5000's Avatar
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    Icon313

    old school...i been using it for years
    99 grand cherokee...mine...gone... now its a 2011 toyota tacoma sport... double cab longbed 4.0 and the are cap to match... im loving it !

    98 grand cherokee...wifes
    nothing special just jeeps.....

    "GET THERE FAST BUT ARRIVE ALIVE "

    automation is the future of manufacturing in the USA... if youre a box packer youre screwed. get educated now


    my jeeps gone. two engines were just too much to handle. now i got me a toyota lets see how long that lasts

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    Quote Originally Posted by boxcab
    A dielectric is not an insulator, it's only a partial insulator.
    Eh?

    A perfect dielectric is a perfect insulator. It should separate two electrical domains, by definition, and the less conductance the better. Of course nothing is going to insulate past breakdown voltage, but we're not talking 200KV here.

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    Registered Jim Hef's Avatar
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    Talking

    Let's hijack this thread and talk about what grease to use in sealed bearings!!!

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    No, I'd rather talk about politics, for the good of all...

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    Senior Moderator Virgil's Avatar
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    Years ago, the thing to use for keeping moisture out was a mixture of Krylon Clear Ignition Sealer and Permatex Spray-a-Gasket.... apply the Permatex immediately after the Krylon and it made a shiny red coating that worked really well. My last Jeep had no distributor, so I didn't use anything on its ignition wiring. before that, I also used nothing.
    "I donít know the key to success, but the key to failure is to try to please everyone." - Bill Cosby


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