Took the boat out yesterday for a run up and down the lake... I noticed a large amount of white flakes discharging from the prop. I have only had this boat and motor for less than a year and this is only the second time I have had it out. I drained and replaced the lower unit gear oil the day before I ran it. I drained it last night to see if there was any water in it after the run. I saw no water, the oil was sorta coffee colored but certainly not white. I have read that the gears infuse air into the oil and that explains the color change but I am still baffled as to where all the white flakes are coming from. One suggestion was unburned oil in the exhaust (two stroke)... I can't believe there was that much. Any ideas?

As far as I know, coffee colored gear oil means water, not air. The gears emulsify the water and oil together. What state was the lube the first time you drained it?

Not sure about the white flakes. Possibly some mineral build up flaking off?

As far as I know, coffee colored gear oil means water, not air. The gears emulsify the water and oil together. What state was the lube the first time you drained it?

Not sure about the white flakes. Possibly some mineral build up flaking off, or the water pump impeller coming apart?

The gear lube looked fine to me, both times that I drained it. No signs of water running out before the oil. The coffee color, to me, wasn't as dark as black coffee, more of a dark cinnamon color (I am not a coffee drinker so perhaps that analogy wasn't appropriate, LOL). The white flakes are like jelly, not a mineral build up. If you look in around the prop nut you can see the stuff all around. The amount of gear oil didn't seem to change either time that I changed it either... wouldn't a leaky seal let it drip out all winter in the basement?

My old sail-drive had a flaw in the casting that allowed water in, but lube didn't leak out.

If it wasn't "milky" looking, it's probably not water in the gears.

The jell-like substance is probably from the fuel/oil mix. I have seen that.

How does it run?

There are several good forums on the popular Merc engines

Just a side question, what lake do you use for the boat, Conneaut, Pymatuning or one in the Meadville area(I can't recall its name right now)? I have fished all of these lakes.

The motor ran great... just an AWFUL lot of of white flakes in the water. Lookin at buying a new prop though. The one that's on it seems a little chewed to me. Hoping a new one will add a little more zip... can't expect a police interceptor 454 ride from a 7.5 hp... but one can still aspire to go a little faster, LOL! I grew up on Conneaut Lake and plan to do most of my fishing there in the Spring and then the Summer early mornings. Pymatuning will be another lake I plan to fish, once I become more comfortable with my boating abilities (need GPS). Wilhelm is just south of me and they have great Crappie fishing there as well, another planned trip. Tamarack is right here in town but no motors. I asked about trolling motors the other night... had a chat with the local Fish Commission Officer, he didn't know, not his lake he said. LOL! Then there is always Woodcock Dam. Gotta be a BIG spawn this year as almost no fish caught by anyone this past winter round here... not really any ice to speak of. I am getting ramped up, waiting for the new trolling motor to be delivered and then I will hit the shallows looking for the Crappie!

As a real young kid, my family would always vacation at Conneaut Lake. My dad and I would go out in a canoe to fish, lots of fun. Don't know if I would want to be out in a canoe now though, to many high powered boats on the lake. Ahh Woodcock Dam was the one I couldn't think of before. A couple of years ago my nephew and I went there to fish. Was a cool morning but the water was quite warm so a heavy fog covered the lake. Took almost until noon before we could see the shoreline from the boat. Everyone that was on the water was giving short bursts of their horn so you had an idea where other boats were located. Fished Wilhelm many years ago when it was over populated with Northern Pike, problem was there were so many it was rare to catch one at or above legal size. Pymatuning is supposed to be good for Walleyes this year as prior stockings seem to have worked quite well. If you used Pymatuning you will need to get a Launch Permit as it is a State Park, the same may be true for Wilhelm. Sorry I can't help with the white flakes, have never seen anything like that. And good luck fishing this year.

Added: A current PA(or any other state) Boat Registration sticker will take the place of a Launch Permit requirement. It is one or the other.

pulled the plugs today and replaced them. From what I can find, the gap for a 1981 Merc 7.5 hp outboard is .040 of an inch. The plugs that were already in were gapped at about .025 of an inch. Could this be why some of the fuel/oil mix isn't burning completely and discharging out the exhaust and turning into this white gel flakes?

What did the plugs look like? A clean burning tan/brown, or sooty looking black? What about the wear on the electrodes?