Spark Plug Trouble

[cstanfield]

I have been having a reoccuring problem with my spark plugs.

After considerable trouble last summer preparing for a 5-week cruise, low power in forward was cured by simply replacing my spark plugs which were not black, oily or sooty. The plugs seemed to have a shiney, whitish coating.

This spring, I tried the new Autolite plugs that Don is selling hoping that the hotter plug would be better.

Yesterday on my way home from Oyster Bay, the low power in forward came back (I had been motoring with out incident for 4 days). We pulled into Bushwick inlet on the East River and dropped the hook. I removed the plugs, scraped and sanded the tips shiney, regapped and reinstalled. Problem solved! We were back underway and home an hour later.

My plug wires are installed in the correct order.

Any thoughts? Timing, points, plug wires?

[Don Moyer]

Very interesting! I don't know of any historical precedence for this problem. Is it possible you're using some kind of fuel additive that may produce this condition as an unintended consequence?

Did the problem start after something had been done to the engine? And are all plugs uniformly white and shiny?

Don

[cstanfield]

spark plug problems

Hi Don,

Thanks for answering. You were very helpful last year ruling out a fuel starvation prognosis for the bogging in forward (the yard was convinced that my problems were fuel related).

With this present incarnation of the problem, the only thing that gives me pause is that i'll experience intermitent over heating from time to time. Taking the boat out of gear, and revving in neutral usually brings the temperature down. It then stays put after putting back into gear and easing into cruising speed.

Yesterday I compared the condition of the plug tips to Spark Plug trouble shooting pictures found online. They most resemble those that are overly hot. A "glazed" appearance. None of the plugs seem appreciably more fouled than the other.

I haven't replaced the wires or the points in a couple of seasons, but the engine is working so well most of the time, I figured leave well enough alone.

Funny that new plugs would get fouled after a relatively short amount of motoring (probably 20 hrs when the most recent faultering took place) and then fixed so completely with new (or in this case cleaned) plugs.

Colin