black crud buildup on driveshaft and inside motor leg - 1968 Sea King 3.5 hp

[69_evinrude]

Hi everyone,

1968 Sea King, 3.5 hp, w​orking on resealing the lower unit...after I pulled out the driveshaft from the motor leg I noticed a bunch of black crispy crud on the top half of the driveshaft and all throughout the motor leg. Is this normal from exhaust buildup from previous years? Or did this thing catch on fire at some point? ha.

This is only my 2nd motor project, so I'm a novice when it comes to this stuff. I was surprised to find all this crud...




Lower unit and driveshaft.







Top half of driveshaft.







Exhaust port/top of motor leg.







Top of motor leg gasket (upside down).












Thanks.

 

[69_evinrude]

I did some research and found this is carbon buildup and there are different techniques to decarbonize. Guess I'll get to work.

Thanks.

 

[jerryjerry05]

YEARS of running did that.