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Thread: 5.7 liter Vortec Problem

  1. #1
    Senior Member MASTER BUILDER
    Join Date
    Sep 2008
    Location
    Red Deer, AB Canada
    Posts
    213

    5.7 liter Vortec Problem

    My son has a 1999 Chev Tahoe with a 5.7 Vortec ehgine. There is a slight tapping / hissing noise coming from the left bank of cylinders. The odd thing is....when it's idling and I remove the oil filler cap the engine stumbles a bit and the idle speed drops slightly. I re-install the cap and the idle picks back up and smooths out. I have never encountered this before and think it's probably related to an intake valve (either the spring, pushrod, valve or seat). Does anyone have any ideas what may be wrong? I will pull the valve cover on Sunday but thought someone on here would know. BTW, the tapping noise is very light - not a knock - just a very light hissing tap.

  2. #2
    Senior Member RACING JUNKIE
    Join Date
    Sep 2007
    Location
    orland pk il
    Posts
    2,429
    POSSIBLE LOWER INTAKE PLENUM(INTAKE MANIFOLD) GASKET LEAK. THIS ENGINE IS KNOWN FOR THIS .BUT MOST OF THE TIME IT STARTS WITH COOLANT LOSS INSTEAD OF A VACUUM LEAK


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