grey discharge from Merc 15 long shaft

[ont_123]

Hi - have a 1995 Merc 15hp Long Shaft 2 stroke - have tested it in a tank, and runs well but quite smokey. After removal from tank, there was a grey/beige discharge from the prop/exhaust and also from the venting just above the cavitation plate - is this anything to be concerned about? Lower lube looked clean - yellow/gold colour, no obvious signs of milky discharge..
If its normal - anything I can do to reduce it? don't want this running into our lake..
PS - there was an oily residue left in the test tank (garbage can) at the water line - dark oily colour.

I also have a jpeg photo if that would help!
Thanks

S

 

[tashasdaddy]

Re: grey discharge from Merc 15 long shaft

welcome to iboats. read this. http://forums.iboats.com/showthread.php?t=207285

 

[ont_123]

Re: grey discharge from Merc 15 long shaft

Thanks!
That was very helpful link.. so it sounds like its more likely just unburnt oil....one of the undesireable aspects of 2 strokes...

Does anyone know whether there is any advantage to using synthetic 2-stroke oil to reduce this? or if there is excess ring wear/loss of compression.. would that increase the amount of this entering the water?

Any other hints to reduce...?

Thanks all
Steve

 

[tashasdaddy]

Re: grey discharge from Merc 15 long shaft

synthetic cuts it down also doing a decarb will help get the build up out of the motor.

 

[ont_123]

Re: grey discharge from Merc 15 long shaft

Thanks for the advice - will try it this weekend, then pull it out of the water and re-check the lower lube for water infiltration - if none - then its simply the discharge - maybe a good run at full speed will help too..,.

Do you have an opinion about adding a cup of white gas ( coleman fuel - naptha)? A number of years ago someone told me that helped keep combustion chamber clean... but not sure if it harms at all.

S