Engine Clatter\Tapping Port on 350 Mercruiser??

Greetings! I have a bayliner victoria with a 260hp 350 engine. This boat was only out once last year & this year it is being used. After about 7 hours of use the engine has developed a clatter on the port. It does seem to quiet down after running 30 minutes or more.

I think it is a valve lifter as I'm unable to feel any exhaust leak. The engine uses no oil, does not smoke & runs well over-all. Although, it feels a little sluggish after the clatter started. Might be just my imagination.

Is this engine prone to a lifter problem?? Can pro-long storage cause problems, ie. sticking lifter??

Would appreciate any info. Thanking you in advance, Larry...

[Griff]

Prolonged storage could have caused the lifter to collapse. If you stored it a long time, one valve would have been completely open and the lifter completely compressed for an extended period of time. It could have weakened the internal spring in the lifter.

[ROUGH WATER]

Originally posted by Griff
Prolonged storage could have caused the lifter to collapse. If you stored it a long time, one valve would have been completely open and the lifter completely compressed for an extended period of time. It could have weakened the internal spring in the lifter.

may be able to solve it with a simple valve adjustment, but if Griff is correct which I would agree a lifter change is the only real fix,

If the engine has really sat that long try running some transmission fluid down the carb while the boat is running in neutral.you will need to increase the fuel flow as you add the fluid. it will Smoke really bad burning off the fluid, but in a lot of cases it will free up a sticky valve train.
Greg

Thanks for the tips! I'm hoping for just a sticky lifter & will try a heavier grade oil, then a lifter additive & if no improvement try the ATF in the intake.

If all fails, Pull the valve cover & go from there! larry...