Servicing Water Pump - Pulled Shaft out...MB5 2 stroke...

...or as Paul calls them "the Flintstone outboard...:>

Following the official manuals i am having trouble getting pump lower case off the gearcase - finally got it off - it prob hasn't been serviced in 10-15 years other than a new impeller...

Problem is two-fold.

1) Go the lower case loosened from the gearcase,but i may have sligtly dinged the case
2) when i pulled up on the lower case to remove it off the shaft...the damn shaft pulled out too i cant get the lower pump case off the shaft..

ALSO - i didnt think this model had ball bearings in lower case:

s2,

As long as you haven't damaged the gasket surfaces, you should be OK to reassemble. If the lower housing is too damaged (looks serviceable in the photo), you will need to replace it. Yes, that bearing belongs there... the same basic design is still in current production in the MFS 4/5/6. The bearing fits closely into the lower housing. If you want to change the drive shaft seal above it (recommended), You can rest the housing in a bench vise, and drive the shaft and bearing down so the bearing pops out of the housing; then the drive shaft (with the bearing still pressed to the shaft) slides out of the housing. Keep an eye on any bearing shims, as you want to keep them in place for correct gear lash. Seeing the rust on the bearing, I would suggest that you verify that the balls and race are OK. They may be fine; if not, you will need to press the bearing off of the shaft, or get a replacement shaft (the shafts come with the bearing already pressed onto them). See the diagram:

Paul, thx. I was able to drive it out. Upon closer inspection it looks like the lower housing has deteriorated and appears to be the reason why water was leaking into the gearcase.

So will order a new upper/lower case

BTW can I order Mercury parts? I was told some of the Merc parts would fit, and might be more available.

It's possible that the sealing areas of your lower pump housing have corrosion, but the photos don't show it to be that bad. Much more likely is that your seals and o-rings are old and brittle and leaking. It's critical is that your drive shaft bearing not be deteriorated. Some rust on the retainer will not be a problem, but the race and balls are very hard, and rust easily. Confirm that the bearing appears and operates perfectly. If there is serious pitting, that will deteriorate under load, spewing metal dust and fragments into the LU lube, effectively acting like valve grinding compound, destroying the LU as it runs.

Tohatsu makes many OEM motors. Yes, Mercury parts will interchange, but they are significantly more expensive, and there isn't any part number cross list. You can locate your nearest Tohatsu parts dealer at http://tohatsu.com/dealersearch/index.html for that matter, the shop where I used to turn wrenches, www.obersheimers.com, can ship parts to you, so they are as close as your mailbox. You can speak with Dale or Eric there, and they will be happy to help you.

Do a complete seal kit (don't overlook the 2 o-rings for the cam rod bushing), and do a complete water pump kit. The stainless cup can sometimes be stuck in the upper wp housing, so if in doubt as to whether you can get the old cup out without damaging the housing, get a new one when you order the wp kit.

Paul, thanks for your help. I have all the parts I need and the factory and 3rd party manual.

the only issue I have (so far....) is the correct orientation of the oil seal. on your parts diagram, and in both manuals there is something that seems to show the correct configuration, but the image doesn't make sense to me...

Actually, the seal would work in either orientation. To clarify, the diagrams show you which side the lip of the seal should face. In your case the diagram shows a seal with 2 lips -- one in each direction. Assuming the seal in your kit has 2 lips, press it in either way, depending on your tooling.

Paul, thanks again for all your guidance. I completed the waterpump and carb rebuild, after 4 pulls on the starter it started right up, runs great, and pumps strong after sitting for 6 months. It still hunts a little bit at idle, but sounds great.