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Silverado is making a knocking noise

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Richmond28, Dec 29, 2012.

  1. j cat

    j cat Rockstar 4 Years 1000 Posts

    using sea foam in the carb you think will stop the piston knock ?

    my guess is this is a lubrication issue. the marvel mstery oil is safe and compatible in the oil when used in the amount I previously suggested.

    sea foam is a solvent. this is for rapid cleaning and must be used very carefully to avoid engine damage.
  2. PantheraUncia

    PantheraUncia Active Member 2 Years 1000 Posts

    I know nothing about the 5.7L carb. engines. I know on my 5.3L fuel injected, Engine Knock is typically created by a few things:


    • Low oil (it has to be really low)
    • Bad Spark plug/spark plug cable
    • Knock sensors are bad ( the 5.3L has 2)
    • (Specifically to the 5.3L....) the 5.3L has issues with the lifters getting gummed up bad over the life of the engine and they will create a knocking sound when the engine is cold.

    Sea foam will help clean the gummed up stuff on the lifters to a certain point. and clean some of gunk on the spark plugs. Knock sensors typically just have to be replaced :-(.

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