Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Burnt Valve?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blazerbob, Jun 9, 2000.

  1. Blazerbob

    Blazerbob 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    214
    Likes Received:
    0
    Location:
    Western NY
    First the background; 83 K5 w/ 81 vette 350 w/new timing chain,cam,gaskets and seals.2 days ago it started idling rough then yesterday when wife was going up steep hill it started popping thru right side of the exhaust. Now every time you "get on it" it pops thru right side once or twice. I changed the whole distributor last night except for coil and still the same[​IMG]. Today 2 people said it sounds like a burnt valve. What exactly does burnt valve mean and does that diagnosis sound correct? Thanks for the help.

    <font color=blue>Blazerbob</font color=blue>[​IMG]
     
  2. ken

    ken 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,244
    Likes Received:
    0
    Location:
    Anaheim, CA
    The easiest way to check for a burnt valve is to do a compression check. If it's low (under 100 psi) then you have problems. It almost sounds like a timing problem, or advance prob in the distributor, but is hard to tell not being there!! Try the comp check and see what that tells you.

    ken
     
  3. Eagle86K5

    Eagle86K5 1/2 ton status

    Joined:
    Mar 5, 2000
    Posts:
    974
    Likes Received:
    0
    Location:
    Whitehouse, Ohio
    Do the compression check....worst case scenerio you will have to pull the heads for a valve job...

    <font color=green>[​IMG]Eagle86K5[​IMG]<font color=red>
    Masonry...It's a Good Thing
    2B1ASK1
     
  4. jimmyjack

    jimmyjack 1/2 ton status

    Joined:
    May 11, 2000
    Posts:
    2,290
    Likes Received:
    0
    Location:
    Tucson Az
    Remove your coil wire so when you crank the engine it'll turn, but not start. If you have a burned valve you will hear a change in the pitch or tone of your motor cranking. It will speed up on that cylinder bcos there is no compression.
     
  5. Blazerbob

    Blazerbob 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    214
    Likes Received:
    0
    Location:
    Western NY
    I just checked the compression and 2,4,6,8 were at 140. 1,5,8 were at 150 and 3 was at 160. I checked timing and that is correct also.

    <font color=blue>Blazerbob</font color=blue>[​IMG]
     
  6. Blazerbob

    Blazerbob 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    214
    Likes Received:
    0
    Location:
    Western NY
    Re: Burnt Valve? not!

    Well I replaced the coil and spark plugs and it is running better now thank goodness! The plugs had some carbon buildup on them. Could the carbon buildup be the problem? The motor only has less than 5,000 miles but has alot of carbon buildup. I don't know if this is from the motor never running over 160 degrees or carb problem. I guess I will see how long these plugs last.

    <font color=blue>Blazerbob</font color=blue>[​IMG]
     
  7. DMK

    DMK 1/2 ton status

    Joined:
    Feb 20, 2000
    Posts:
    757
    Likes Received:
    0
    Location:
    CINCINNATI, OH
    Fouled plugs will diffently do this. Make sure settings are right on carb. May have to go one heat range up on plug.EX.ac44 to ac45's. Had to do this on my 66 grand prix not enough highway driving. Usally all plugs will be carboned up if it was the carb. were the plugs carboned up or oil fouled?
     
  8. Blazerbob

    Blazerbob 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    214
    Likes Received:
    0
    Location:
    Western NY
    Yes the plugs were carbon fouled! I think the carb may be screwed up. If someone buys my 80 K5 parts rig I will use some of that money to buy a new carb. I already had AC r45ts plugs in it.
    thanks for all the suggestions guys!

    <font color=blue>Blazerbob</font color=blue>[​IMG]
     

Share This Page