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Signs of a collapsed lifter?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by mountainexplorer, Jun 6, 2003.

  1. mountainexplorer

    mountainexplorer 1/2 ton status

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    What are the signs of a collapsed lifter?

    How about a sticking valve or a valve starting to go bad?

    My symptoms I have in a '77 350 include backfiring back through the carb when there's a load put on the motor and I give it gas (just to the point before opening the secondaries on the carb).

    It idles kind of rough, but seems smooth at higher rpm and is fine without much of a load on the motor.
     
  2. MousePowrd

    MousePowrd 1/2 ton status

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    Usually a collapsed lifter or flat lobe will idle fine but as rpms and load climb, backfiring can occur (if it is an exhaust lobe) and intake lobe will just lose power.

    Do you have any ticking noises? A collapsed lifter or flat lobe may take the preload off the rocker and cause it to come loose or bang around

    I would guess your problems are ignition related if you dont have the above symptoms
     
  3. R72K5

    R72K5 Banned

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    everytime ive seen an engine popping out intake its been a worn off cam lobe /forums/images/graemlins/frown.gif
     
  4. mountainexplorer

    mountainexplorer 1/2 ton status

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    It idles ok, and revs fine when in park or neutral. Regular driving, it does ok. Just when I really get on the throttle or for example when I was trying to tow my car trailer with it, it will backfire.

    It has a constant ticking noise that seems to come from the right bank (pass side). I pulled the valve cover and saw nothing visually wrong. Seems to me from holding a long wooden stick up to the head, that the noise is loudest around #6. That also probably explains why they had #6 plug wire disconnected when I got it.
     
  5. mountainexplorer

    mountainexplorer 1/2 ton status

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    It wouldnt surprise me if it was a cam lobe going flat.
     

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