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355 valve seal issue

Discussion in 'Technical Q&A' started by 308GTS, Feb 21, 2006.

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  1. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,223
    TN
    #1 308GTS, Feb 21, 2006
    A friend of mine has a 95 355. He was told the valve guides and seals are in need of replacement. It is now consuming oil. I am not very familiar with 355s so I thought I would ask the ?. I remember reading about this problem however they were replaced 4 years ago at a dealership. It is common for them to leak again like this? What causes this? Is there an updated seal or will it eventually happen again to all of them? Thanks.
     
  2. Dr_ferrari

    Dr_ferrari Formula 3
    Consultant Professional Ferrari Technician

    Nov 2, 2003
    1,071
    Pocono Sportscar
    Full Name:
    Jim McGee
    #2 Dr_ferrari, Feb 21, 2006
    the early 355 used bronze valve guides. the problem was they would quickly wear out.

    the new valve guide is made of sintered steel and lasts much longer.

    If the guides were replaced four years ago, they should have been the steel type. are you sure they replaced all the guides? maybe one of the valve seals is broken or leaking.

    regards, Jim
     
  3. Nick

    Nick Formula Junior
    Sponsor Professional Ferrari Technician

    Oct 31, 2003
    506
    Full Name:
    Nick Scianna
    #3 Nick, Feb 22, 2006
    Last edited by a moderator: Sep 7, 2017
    We have done a fair amount of 355 heads, we have new valve guides & valve seals for the 355's. Below is a few pictures of the valve guides that we are using on 355 heads now. We also use a custom viton seal for our clients.


    In the photo below, the copper colored valve guide on the far left is the original guide and is made of a copper alloy material. This is a soft material that causes the guide to wear quickly and fail prematurely. The guide in the center is made of iron and comes standard in the head that Ferrari uses to replace heads with failed copper alloy guides. Notice how it is straight with no flange, in our opinion this could allow the guide to "walk" down into the heads and cause severe damage. On the far right is the silicon bronze guide we use to replace the original flanged guide.

    The next photo below are the guides we have custom build to replace the non-flanged iron guides. Notice the small round "bump" we leave to insure the guide can not walk down into the head.
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    Image Unavailable, Please Login
     
  4. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,223
    TN
    #4 308GTS, Feb 23, 2006
    Thanks Nick. Superb detail as always. The info is greatly appreciated. I will tell him to sent the heads to you once he gets them off. Hopefully they won't leak for a long long time after that. Thanks Again.
     

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