Merc 50 Impeller Problems

Okay, dropped the lower unit in order to change out the impeller (pump kit should be here wednesday). I thought maybe I had a bit of a seal leak as there was a bit of gear oil on the skeg...or I thought maybe it was just unburnt two stroke (here's to good dreams). Well when I dropped the lower unit there was a tonne of goo there (gear oil mixed with water I guess). It appears to have come up around the water pump. I assume there's some seals there that need replacing, but for the life of me I can't get the bottom half of the pump out. Any tips? Do I have to pull the prop shaft to get it out? It doesn't budge at all....I'll break it if I have to...my dealer says I can get the housing cheap...but I don't have the tool to remove the prop shaft...and would prefer not to purchase one.

Also, I noticed that if I pull the vertical drive shaft up, there is a tonne of free play there...but none if I push it down..is this normal? Or should I just break down and rebuild the whole thing.

This is an 86 merc 50 3cyl two stroke. I forget the ser# but that info is correct.

Ian

Re: Merc 50 Impeller Problems

i just had the same trouble with an 86 merc 60hp. i soaked the thing in penetrating lube, and let it sit a day, then carefully pryed back and forth from each side with a slotted screwdriver, after about 15 tries, she came loose. i also replaced the entire pump housing and seals, and impeller, cost 80 bucks canadian. takes a lot of patience to finally get it to wiggle loose, then it slides right up off the drive shaft like nothing, had it together in 20minutes, and was on my way to the bay. just push it from the front, then the back, then the side, then the back then the front then the side, etc... it will wiggle free after you feel like giving up.

Re: Merc 50 Impeller Problems

Thanks, they should be the same lower unit, so I will work on it tomorrow...since I have most of the day to get 'er done. Did you have the same grease problem as me? There was quite a bit of it in the leg...about a cup full.

Ian

Re: Merc 50 Impeller Problems

i was prying on mine, then put it back on since i couldnt get it off, then took it off again after running it, and there was a bunch of goo, crap, oil everywhere, all over the pump housing. it took me a long time to finally pry that bottom peice off, and then there is 1 seal, and 1 rubber o-ring, if i remember correctly. they both fit onto the new water pump base, one goes around the area the drive shaft fits through, the other is a o-ring that seals between the water pump base and the lower leg housing. i was worried when i saw all that gunk as well. but im too stubborm to pay someone to fix it, i will likely blow it up before i pay someone else to repair anything, lol

Re: Merc 50 Impeller Problems

Yeah, it seems the gear oil was getting through the shaft seal, although the pump housing is discolored around the sides too, so both seals may have been leaking. I'm going to replace the housing, hopefully it is already included in the kit I ordered, if not, I'll order the housing on Monday. Makes sense though, I changed the gear oil just before the end of the season last year, and noticed the old oil was very very old (black) and there was very little of it. So I drained it for a few days, filled, let sit for another day to get any bubbles out, topped up and screwed the caps in. After a very long day in rough water I noticed gear oil dripping down the skeg from the prop. I figured I blew the prop seal (I didn't thankfully) so just packed it in for the season. After removing the lower unit this weekend I found the source of the oil. It must gel up quite a bit when forced through the water pump, because it was the consistancy of very thin grease...and mostly blackish brown. I've got it all apart and cleaned ready for the new parts, and it's currently draining out as well. I will fill with fresh..and maybe not be so aggressive about making sure its full this time. This may have been the root of the problem...overfilling it causing it to force past the seals when the oil heated up....that's my theory anyhow.

Ian