355 - Silicone on paper gaskets | FerrariChat

355 Silicone on paper gaskets

Discussion in '348/355' started by alexanderfitu, Aug 30, 2021.

  1. alexanderfitu

    alexanderfitu Rookie

    May 23, 2020
    Full Name:
    Hi all

    In the middle of doing a Major on my 355. I have the rocker covers off to check timing etc, and have noticed that the previous mechanics have used high temperature silicone on all surfaces that use a paper gasket, in addition to the paper gasket:

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    In my experience (Mercedes workshop) you never use silicone sealant in addition to an existing gasket, and especially not where there is a possibility this sealant can enter the engine oil ways. I have meticulously cleaned all the surfaces, and intend to use just Loctite 3020 spray on the paper gaskets. Can anyone weigh in?
    Much appreciated.
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  3. JoeCab

    JoeCab Rookie

    May 27, 2014
    Full Name:
    Joe C
    I've had very good luck using Permatex Ultra Grey in addition to paper gaskets.

    However I use a specific technique - with a gloved finger I spread it on the gasket as thin as possible (so you can almost see through it) and the let it set up for a few minutes. It should still be semi-tacky but not wet. This insures there isn't any way it can squish out and clog things up, but still does an excellent job of preventing leaks.
  4. 26street

    26street Formula Junior

    Jan 30, 2021
    Westchester New York
    Full Name:
    Mark k
    Yes M/B is correct about having sealer getting in to the engine and M/B like other high cars spec the torque and clearances with a gasket being used , by a lot of top engine builders use “Honda bond” and works the best And have not had anything leaking after using it on several of my vehicles

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  5. John Glen

    John Glen Formula Junior

    Dec 30, 2009
    Victoria, B.C, Can.
    Full Name:
    John Glen Wesanko
    I also used a very thin application of Honda Bond. No problem,no leaks. Any paper gasket will have to be replaced after one use. A very thin addition of sealant will reduce the frequency of removal (because of leaks)
  6. Zamboniman308

    Zamboniman308 Formula Junior

    Feb 2, 2020
    Chicago IL
    There are 2 kinds of mechanics. Those who've resealed an engine for leaks on their own dime.. and those who will have to reseal on their own dime. Usually only takes once to learn the lesson.
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  8. vvassallo

    vvassallo F1 Veteran

    Aug 4, 2006
    Palos Verdes
    Full Name:
    Vince V
    Another vote for Honda bond. Look, your car is over two decades old; stuff warps. Honda bond insures a good seal. Use it everywhere there are gaskets. Everywhere.
    26street likes this.

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