The saga continues:
Strange coincidence; I'd put this aside for the last 20 days (took awhile to get the parts), and only just this morning decided to put it all back together and lo and behold there are a couple new posts from yesterday. Here’s some feedback.
(The part reference numbers below refer to the thumbnail in my original post. They are different than what some parts
sellers use! i.e. Iboats bearing part reference number may be 13 but Mercury Marine
may have it as 11. Same picture, different number. So if you are following this closely you should use my thumbnail in the original post.)
On the 10th you described how to get the top bearing, #13, off the drive shaft. That is not the problem. My issue is that the bearing is stuck in the carrier portion of the water pump base, #17. I think (and the shop manual says) that I will likely destroy the bearing and or seal when this bearing and seal are removed. The manual says this even with their assumption that one uses the special tools.
Once out of the carrier, I'm sure I would have gotten the bearing off the shaft in the manner you describe. However, upon a second look at the shop manual with fresh eyes, and seeing how the sketches of the procedures are portrayed I now realize that they expect that the bearing just comes/pulls/drops out of the carrier easily with out having to hammer on it. No way on mine! On my unit I think corrosion
has siezed the two together where the bearing is seated into the female bearing carrier area of the water pump base, (#17). The bearing is stainless steel
and pump base is aluminum
. This was the same problem for me getting the water pump base out of the lower unit casting. Took me several hours of carefully warming, wd40, tapping, cajoling, cussing to get it out, and yes there was just a small amount of that white aluminum
oxide & corrosion
in that interface too. (you don't need to do this to change the impeller or gear oil. I just wanted to see and fix why my gear oil vent hole was plugged.)
One cannot hammer the bearing, #13, out of the carrier with a correct size socket (or what ever mandrel you can devise). The diameter of the hole in the water pump base that the drive shaft goes through is only a few 64ths" larger than the actual shaft diameter. There is no visible lip of the bearing to hammer on. It needs a special "expanding shaft" puller from below to pull (or slide hammer) it out. You might be able to hammer it out with a screw driver at an angle thru the drive shaft hole but you will definitely ruin the bearing and seal doing that, (and run the risk of breaking the $85 cast aluminum pump base). Ages ago I removed a few bad wheel bearings and seals in this manner so I have an idea how it goes.
I found changing the impeller pretty obvious. The big caveat is to not completely unscrew the shift link clamp (and lose it) in the little hole in the exhaust
housing. And though I haven’t got there yet I read that its a pain to get the shift linkage, drive shaft and water pump tube lined up to reinstall. A trick was to use some small wire to hold stuff as you slid it together. I found some threads or posts that discussed this, sorry no link though. If you need it here is a shop manual I found online. Boatinfo - Mercury Service Manual for 2,2-2,5-3,0-3,3 hp
I don’t think you can download it or print from it but I have it on my laptop
next to me in my shop. And I have printed some pages as screen
shots but the illustrations and text are hardly useful. Maybe someone more techy can do this but that ain’t me
My impeller was really shot, just stub arms where the vanes used to be, and there was a thin layer of black rubber goo smeared inside the stainless steel cup insert that the impeller spins in. I took all the parts to the merc mechanic to answer a few questions, (he was very nice). He commented that when impellers look that burned up it is likely that the stainless steel cup insert (#23) that the impeller spins in has also, itself, spun inside the upper water pump housing (#24). There is a tang protruding from the bottom of this cup insert and it keys into the upper water pump housing. The tang normally prevents the insert from spinning inside the housing. But the friction of the melting impeller against the insert cup heats up the cup and housing and eventually the tang starts plowing its way thru that area of the melting/gooey plastic housing thus allowing the insert cup to spin, or at least rotate out of alignment. This creates a misalignment of the impeller/cup insert/housing assembly with the drive shaft. They are mounted a bit out of line in that the hole for the drive shaft through the cup insert is not exactly in the center of the cup itself. This is what makes the pump pump; the impeller kind of wobbles around in there in an eccentric motion as it spins with the drive shaft. (remember this is a new used motor to me, I never run my motors dry) So if they are out of alignment then it won’t pump as well and may create excessive heat and wear in a newly replaced impeller. It may also crack the plastic housing itself or put a side ways pressure on the drive shaft. It looks like mine might be ok, the mechanic said when they look like mine he not only installs a new impeller but replaces the whole pump housing. Of course we all understand why; a half hour of his labor is more than the cost of a complete rebuild
kit and pump housing. Me, my labor is free and I like “taking apart stuff” and parts cost retail $$$ to me. I will use it as is and monitor
the water pump flow. Having done this disassemble once I know i can do it again in less than an hour.
I heard/read somewhere of a guy that had an aluminum prop and was always breaking shear pins. A plastic prop solved
the problem. I think he said there was an improvement in performance as the prop blades flexed to give more bite out of the hole and then as top end was reached it seemed to go faster, but don’t hold me to this. My prop is plastic but i’ve only run it 15 minutes before deciding to do some preventative maintenance
and change the gear oil,,……. leading to this thread. Another guy with the same problem wrote, (maybe it was Donradcliffe) that he made SS ones to solve his shear pin breakage. I have a plastic prop and brass pins but just in case I made some extras out of same diameter brass bolts I had lying around. I’d be a bit nervous about subbing ss for brass pins. They are there for a reason…… but if it works……
I’ve spent so much time writing that I don’t know if I can finish the reassembly today. But will report back when I do.