Unidentified motor noise

[Bratcher4079]

I have an 89 OMC Valiant VIP with a GM V-6 motor. The motor is making a strange tapping sound. The sound seams like it is metal on metal. From what I can tell it's most prevalent in the distributor area of the intake manifold. Or at least it seams the loudest there while trying to listen with a stethescope but it very hard to tell. When I bought the boat it wasnt making this sound. The boat sat in my driveway and when I cleaned it up two weeks later and started the engine the tapping sound was present upon the motor starting. The noise speeds up and slows down as the rpm increases or decreases. The sound is present with the drive in nuetral or in gear. I disconnected all of the belts to ensure it wasnt the water pump, alternator ar power steering pump. You cannot hear the noise in back of the boat at the outdrive. New plugs and oil change was just completed and that didn't help. Any ideas???

 

[86 century]

Re: Unidentified motor noise

I my nearly useless opinion the place to start would be the lifters.
If your eng is the 4.3 with adjustable rocker arms it is possible to play with the lash a bit to get the lifter to pump up if that is the problem.

Next on the list would be the distributor its self if it has gotten sloppy the rotor can be hitting the cap.

 

[tpenfield]

Re: Unidentified motor noise

I have an 89 OMC Valiant VIP with a GM V-6 motor. The motor is making a strange tapping sound. The sound seams like it is metal on metal. From what I can tell it's most prevalent in the distributor area of the intake manifold. Or at least it seams the loudest there while trying to listen with a stethescope but it very hard to tell. When I bought the boat it wasnt making this sound. The boat sat in my driveway and when I cleaned it up two weeks later and started the engine the tapping sound was present upon the motor starting. The noise speeds up and slows down as the rpm increases or decreases. The sound is present with the drive in nuetral or in gear. I disconnected all of the belts to ensure it wasnt the water pump, alternator ar power steering pump. You cannot hear the noise in back of the boat at the outdrive. New plugs and oil change was just completed and that didn't help. Any ideas???

Valve lifter and/or valve adjustment.