Sealing fresh water tank lid

Discussion in 'Motorhome Chat' started by joggerman, Feb 18, 2010.

  1. joggerman

    joggerman Read Only Funster

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    The large access lid to my watertank has a O ring to seal it.
    In addition it seems to have a type of white grease on the ring.
    The lid obviously needs to be a tight seal to avoid water seeping out the lid.

    What type of grease do you think I would need to use?
     
  2. scotjimland

    scotjimland Funster Life Member

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    There is proprietary food grade 'O' ring grease on the market but not commonly sold in high street stores..

    I use petroleum jelly on tank 'O' rings and seals .. 'Vaseline'
     
    Last edited: Feb 18, 2010
  3. JeanLuc

    JeanLuc Funster

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    If the O-ring is in good condition, I would not have thought you would need any grease. Ours certainly has none and it is opened / closed frequently. I open it after every trip to remove the drain plug, then leave it propped across the screw collar to allow air-flow until closing it before the next trip.

    Philip
     
  4. joggerman

    joggerman Read Only Funster

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    I presume the grease is to seal it well, but also to make it easier to turn and prevent wear to the O-ring?
     
  5. hilldweller

    hilldweller Funster Life Member

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    Gets my vote.

    I'd use silicon grease. I believe petroleum based grease does nasty things to rubber. It might not be rubber.

    But there is a negative - depending on the contours, grease can make it too slippy and the pressure squeezes the ring out. I've made that mistake with a flat rubber washer.

    Our tank seal is dry but it is hard to turn, I might grease it.
     
  6. scotjimland

    scotjimland Funster Life Member

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    Unless you know what the ring is made of it's hard to say what is best..

    Petroleum jelly can affect some types of materials and silicone grease will swell silicone O rings ..

    Personally I've never has a problem using Vasaline on tank cap O rings, but if it were a critical O ring in a fuel or brake system I would use as recommended by the makers ..

    but heh, this is a tank cap, better it lubricated than left dry, and if the ring was affected by the grease it's no big deal.. cheap as chips to replace..
     
  7. steles

    steles Read Only Funster

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    The only grease to use is Silicone, available from plumbers merchants, on line or RS .
    The seal is probably EPDM. so be careful if using any thing else.
    Steles.
     
  8. bigfoot

    bigfoot Funster

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    Lard or olive oil
     
  9. joggerman

    joggerman Read Only Funster

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    Thanks for all the suggestions..........
     
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