1980 80hp Merc carbon build up in exhaust

[rookie456]

I have been rebuilding a 1980 80 hp 4 cylinder Merc. Serial #5773499. I bought it used. Low compression on cylinder 3. The previous owner was able to start the motor when I went to pick it up. A lot of the wiring was corroded and exposed. I could see sparks all over the motor from exposed wiring. When I got it home I tore the whole thing apart. Low compression in cylinder 3 was from stuck rings. I was very surprised at the amount of carbon when I opened the exhaust cover. This is the first outboard I have torn apart. Is the amount of carbon in the picture typical?

 

[GA_Boater]

Did the PO do a lot of low speed trolling? That is a lot of carbon build up. Two strokes are especially sensitive to exhaust tuning and the carbon could be causing running issues. I would check the exhaust tube in the midsection for build up too. The carbs may be running rich as well.

When you get her running again, do the Seafoam mosquito fogging trick and continue with the recommended Seafoam treatment in the fuel. 50:1 fuel pre-mix with 1 oz. Seafoam per gallon.

 

[rookie456]

Thanks GA Boater. I bought it off craigs list, so I am not sure what the PO used it for. I checked the exhaust tube, there wasnt any build up in there. I have rebuilt the carbs and the fuel pump, and I will be using seafoam in the fuel. Hopefully I will have it all put back together in the next few weeks.

 

[1nebel0]

Once a year fogging with Sea Foam or the Mercury Product....That motor has never been foamed.....

 

[Texasmark]

Look in the archives for the word "Decarb". Do the process then keep Sea Foam in your fuel/fuel mix per the recommended ratio on the can. It works!

Mark