Mercury Thunderbolt 110 9.8HP Hissing

Discussion in 'Boats and Motors' started by duckhound, Jul 8, 2008.

  1. I have recently bought a boat with a 1978 Mercury Model 110. It takes a few pulls to get it started, and does not want to run in gear for long while idleing. One note is while pulling the cord when starting it, a hissing noise can be heard coming form under the if pressure has built up where it should not be.
    I have looked the motor over and do not see any signs of ripped gaskets or the like. Wold this be a sign of a blown head gasket? I have also heard of a valve (reed valve??) that keeps the fuel/air mixture going in one direction, and that could be failing.
    Anyone heard of this issue? Suggestions? Take it in for service??
  2. sure sounds like a head gasket , pull the cover off ,have some body crank it over while you keep your head and ears closer to the motor , find that leak , not a hard job to repair , just make sure you clean all the old gasket off , real clean. p/s those were realy great motors.