Plugs fouling with metal

[svenngali]

My 1977 Merc 150 outboard has an issue at higher revs. Seems fine when idle is low, but when I go fast, high revs, one or two of the plugs will foul with a metal/aluminum material. If I scrape them off, it will run fine again till I get the revs up again. Any ideas of whats happenning? THANKS.

 

[Mi duckdown]

Re: Plugs fouling with metal

NO. but you need to do compression check soon

 

[fishrdan]

Re: Plugs fouling with metal

one or two of the plugs will foul with a metal/aluminum material.

Any ideas of whats happenning? THANKS.

Melted piston....

 

[Mi duckdown]

Re: Plugs fouling with metal

+ 1

 

[dwco5051]

Re: Plugs fouling with metal

A good chance that it has been running too lean due to carburetor problems. All posts are pointing in the right direction. If the compression test still shows equal in all cylinders I would still pull the heads to see how much damage has been done. Unfortunetly it may be too late and a rebuild is in order.

 

[Faztbullet]

Re: Plugs fouling with metal

That is aluminum throwoff(errosion) from the eyebrow of the piston from preignition. If it cylinders 1 & 3 the trigger is failing or the timing is off big time. This engine does not have a "head"...

 

[dwco5051]

Re: Plugs fouling with metal

That is aluminum throwoff(errosion) from the eyebrow of the piston from preignition. If it cylinders 1 & 3 the trigger is failing or the timing is off big time. This engine does not have a "head"...

Oops, read the post fast and and thought it said a different engine, too late at night or I need to get my bifocals calibrated. Peek through the spark plug hole.

 

[Gomer50]

Re: Plugs fouling with metal

This is what happens with bad timing and or cooling problems.I would suggest you look at your timing and make sure you gettin enough cooling when running. I hate to say this but damage has already started in your case. Take a compression test to see what she say's.

 

[svenngali]

Re: Plugs fouling with metal

Thank you for all the posts....doesnt sound too good, guess a compression test first, then check the timing. Hoping it can still be saved. I'm thinking it was #1 and #3 cylinder Faztbullet and excuse me for not understanding your phrases; 'the trigger is failing' and 'it doesnt have a head'? could u please explain, thanks.

 

[Gomer50]

Re: Plugs fouling with metal

trigger on your model is a distributor.Cylinder block and head is all one piece.

]

 

[j_martin]

Re: Plugs fouling with metal

Bottom line is your engine ain't cool.

Cooling system.
Lean, ie plugged up carburetor, fuel pump, etc.
Timing, ie too fast, or cross firing through cracked distributor.
Air intrusion, ie seals. (another version of lean.)

If you haven't already totally wrecked it running it like that, you will soon. Some people don't quit till they can inspect wrist pins though the spark plug hole.

 

[svenngali]

Re: Plugs fouling with metal

Thanks again guys, I'm a newbie here and dont know much about outboards. I'm hoping the damage isnt too severe as I stopped running the boat when I was told I would blow it up if I kept taking it out to the lake. I had it out twice in total when the probs started, so hoping shes salvageable. Starts and idles fine on shore with the muffs on, but maybe I shouldnt even be doing that?