Headlight Vacuum "Manifold" Leakage

Discussion in 'Wrenchin' Secrets' started by Gary Anderson, Jan 3, 2020.

  1. Gary Anderson

    Gary Anderson Well-Known Member

    '68 Riviera

    Question about this piece of the headlight vacuum system. Below is the part that hides next to the battery, and diverts vacuum to either up or down for the headlights. Smaller hose obviously comes from the headlight switch, and pulls diaphragm to direct vacuum to either side of the headlight actuators. This side of the manifold works fine and holds vacuum.

    My question is regarding the other side of the manifold. The large, round center port has continuous vacuum to it, via the vacuum canister (I presume). The other two oval ports go to the headlight actuators - up or down side(s). So with vacuum (using my mouth on the larger hose, as connected in pic) is applied, vacuum goes directly out one of the oval holes, and to the other oval hole when vacuum is applied to the diaphragm side. But I have a very slight vacuum leak, both in each opposite oval port and out the seal end of the internal shaft (on the very end, much like the piston in a brake master cylinder).

    Is this normal, or should I go looking for another complete manifold? It's only a very little leakage, but I don't know how much is too much.

  2. BBBPat

    BBBPat Well-Known Member

    Is the leak internal or external? Can you immerse it in soapy water and see the leak? If its external, put a vacuum source on it ( a few inches) and something to seal it with like JB weld or epoxy, and keep the 1-2 inches of vacuum on it until it sets up. If the diaphragm inside is leaking its time for some microsurgery. Wasnt that BRIZ that made up an electric drive for his? Pat
    Gary Anderson likes this.
  3. Briz

    Briz Platinum Level Contributor

    I did go electric with mine using 67 Riv parts. Planning on redoing that with the Mazda actuators in the future. As to your question I dont think the leak is anything to be concerned about and might even be built that way to keep the light in the retracted position.
    Gary Anderson likes this.
  4. buick64203

    buick64203 Just plum crazy Staff Member

    You can try spraying some wd-40 in it. The internal valve might be stuck or not moving in it's full travel
    Gary Anderson likes this.
  5. Gary Anderson

    Gary Anderson Well-Known Member

    The leak is internal - as if the inside rubber plunger isn't making good enough contact with the barrel anymore. I did depress the plunger by hand and put some silicone grease in the barrel to help it seal better; not sure if it helped or not. Maybe by sitting like that for a day or so... I know there are oil addtives available to seal engines up - products that work by chemically swelling the rubber seals but I think Briz is probably right, that it's no big deal. The little bit of vacuum leak wouldn't affect engine vacuum anyway.
  6. 1969RIVI

    1969RIVI Well-Known Member

    Briz from what year, make, model of mazda were you planning on sourcing the actuators from? I'm embarking down this same path for my Riv and was going to use actuators from Princess Auto (your Habour Freight) but they're $80-90 each and would love to do it cheaper.
  7. Briz

    Briz Platinum Level Contributor

    Believe its from early 2000's Miata . Should be able to get them at any junk yard
  8. 1969RIVI

    1969RIVI Well-Known Member

    Thank you Briz I'll look into it, cheers!

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