What's in the water??? (black granules)

While working on my 1973 Evinrude 9.5 sportwin, I noticed an odd substance floating in the water barrel I use when testing the motor. They were black and the size of large grains of sand. When I picked some out of the water, they were somewhat hard and left light black marks on my fingers. I was afraid my impeller was falling apart so I dropped the lower unit and opened the housing. The impeller is fine (i'll replace it anyway as long as I have it open) so what is this stuff and where is it coming from?
Thanks!
E

Re: What's in the water??? (black granules)

Perhaps it is sand that you picked up on your last outing. If it were inside the exhaust housing, it would be covered by the unburnt fuel/oil goo.

Re: What's in the water??? (black granules)

Old carbon buildup that has broken off and gotten blown out the exhaust. Not uncommnon on older motors... Might be telling you it's time to run some Sea Foam Deep Kreep through it to clean out the innards...

Re: What's in the water??? (black granules)

Chinewalker said:

Old carbon buildup that has broken off and gotten blown out the exhaust. Not uncommnon on older motors... Might be telling you it's time to run some Sea Foam Deep Kreep through it to clean out the innards...

Click to expand...

seconded.

Re: What's in the water??? (black granules)

Brief history...I bought this motor on Craigslist and was told that it had'nt been run in 4 years. Under the cowling was FULL of wasp nests and spider webs from being left outside for so long. I checked the compression, rebuilt the fuel pump and carb then replaced the coils, reset the points and replaced the plugs. I added sea foam to the gas and pulled the starter. It started on the third pull but only for 30 seconds or so. Wasp larvae and dead wasps came out of the exhaust. After the third or fourth time starting it and working on getting it to idle, I noticed the black stuff floating in the water. I bet you are right, it is probably old carbon buildup that has broken off and gotten blown out the exhaust. I'll get some Deep Kreep and run it through. Thanks.