Mercruiser 350 Exhaust manifolds blocked

Discussion in 'Gas Engines' started by sbarton661, Apr 14, 2010.

  1. sbarton661
    Joined: Mar 2010
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: texas

    sbarton661 New Member

    My engine continues to overheat. I blew air through the exhaust manifolds and there seems to be blockage. What would cause this and why would both be blocked?
  2. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Open the drain cocks at the bottom of the manifolds. There probably will escape no water. With a thin object punch through the sludge: the black goo coming out used to be part of the manifold walls. Removal may take a lot of flushing.
  3. gonzo
    Joined: Aug 2002
    Posts: 15,818
    Likes: 1,221, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    They are probably corroded. It is time for new manifolds.

  4. Jango
    Joined: Aug 2005
    Posts: 519
    Likes: 7, Points: 0, Legacy Rep: 63
    Location: Mid Atlantic

    Jango Senior Enthusiast

    Your Problem may go beyond rust, sludge. If the motor has been repeatedly overheated, the interior of the rubber exhaust hose could be blistered to the point of causing a plug. This has happened to me
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