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What does a burned exhaust valve look like?

Discussion in 'The Hokey Ass Message Board' started by Kevin Lee, Jan 22, 2006.

  1. Kevin Lee
    Joined: Nov 12, 2001
    Posts: 7,582

    Kevin Lee
    Super Moderator
    Staff Member

    I know you can read spark plugs. Wondering if there's a similar technique for valves?

    Popped the heads on my flathead and noticed the exhaust valve in #1 looked grey. Basically a sort of "fogged" greyish white around the outside of the valve. I've heard before how the no. 1 cylinder sometimes runs lean and in turn gets hot, causes problems with soft header bolts, etc.

    It doesn't really look like it's in bad shape - but definitiely looks different than the other fifteen.
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 55,934

    squirrel
    Member

    A burned valve has a notch or flat spot at the face (the part that contacts the seat), so it does not contact the seat at the burned part.
     
  3. Any degradation or pitting of the seat area?
     
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 55,934

    squirrel
    Member

    heres one I found with google image search....

    [​IMG]
     

  5. Steve Ray
    Joined: Mar 2, 2001
    Posts: 693

    Steve Ray
    Member

    The valves in my Alfa Romeo motor actually turned black-they had a charred appearance and one was cracked with a chunk missing. Yeah they looked like the picture.

    I did see a set of burnt flathead valves once-similar appearance and the edges were crumbled away. A burned valve will eventually lose big chunks so if you have any doubt replace it.
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 55,934

    squirrel
    Member

    Sounds like no 1 is running properly, and the other 7 cylinders are running a tad rich.

    Normally the exhaust valves will be white, grey, or tan, if the fuel mixture is right and the engine isn't burning a lot of oil.
     
  7. 51 MERC-CT
    Joined: Apr 5, 2005
    Posts: 1,594

    51 MERC-CT
    Member

    Here's a really bad one out of a flathead. :)

    [​IMG]
     
  8. Kevin Lee
    Joined: Nov 12, 2001
    Posts: 7,582

    Kevin Lee
    Super Moderator
    Staff Member

    I can live with this explanation. The rest of the cylinders did have a pretty heavy carbon buildup. I'll try to get pictures later.
     
  9. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    Also might just have lots of pitting on seat without any big area gone.
     

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