2006 Tohatsu 4hp MFS4BD water pump lower case

[DamianJP]

2006 Tohatsu 4HP MFS4BD

Im up to the water pump and have some questions. I have done these before but with other designs.

I have the OEM service manual but still need some stuff cleared up, thank you.

When I goto pop the water pump lower case up do I have to be careful of the bevel gear "B" (Part 11 on diagram) dropping off into the lower unit? If the shaft gets pulled up or moved will the the bevel gear "B" fall off inside?

Or is it being retained by the bevel gears A and C and/or something else?


DIAGRAM

https://www.boats.net/catalog/tohatsu/outboard/2006/4hp/mfs4b/gear-case-drive-shaft

Thank you,
DamianJP

 

[pvanv]

Why pull the lower case? But if you do, yes, the gear will fall off. You can invert the whole thing and the gear will stay on the shaft by gravity.

 

[km1125]

Yea, I'm confused too. You should not have to move the lower case to replace the impeller, or do the 'whole' water pump kit.

 

[DamianJP]

Part 21 pump case (lower) is pitted and owner wants new. Someone left her sitting up with saltwater or something. Got funky.

When I pull part 21 pump case (lower) up and slide it up the shaft I was worried about the part 11 bevel gear "B" coming off the tip of shaft if the shaft got pulled too far up.

I dont want part 11 bevel gear "B" falling off into the lower unit deeper.

Do I need to make sure the shaft stays down the whole time working on the pump case (lower) area to keep the bevel gear "B" from moving or coming off?

Thank you Pvanv and Km1125 for the responses/help.


DIAGRAM
https://www.boats.net/catalog/tohatsu/outboard/2006/4hp/mfs4b/gear-case-drive-shaft




Thank you,
DamianJP

 

[DamianJP]

So if keep the drive shaft down and in place while sliding the old lower pump case up I should be fine?

Just keep drive shaft in place until im done reinstalling new lower pump case?


Thank you for you time and help,
DamianJP

 

[pvanv]

Or just slide the gear back on after you're done.

 

[DamianJP]

Was stuck on pretty good but got the water pump lower case off without disturbing the shaft. The water pump lower case started to come up with the bearing slightly stuck in the case pulling the shaft with it. Once I got the case up abit I held it up with 2 flathead screw drivers and LIGHTLY tapped the top of drive shaft down to slowly start to push bearing down off water pump lower case. Pulled it up again further, set flatheads in place and tapped down again. Making sure not to pull the shaft all the way up off the bevel gear and needle bearing below. Did this 3-4 times slowly. Super LIGHT taps. Worked like a charm.

1 step closer to finishing maintenance on her.

List of stuff being done or done already...
New spark plug gapped .9mm
Engine oil change
Lower unit oil change
Checked coil Ohms and gapped to .5mm
Adjusted valves IN .10mm EX .15mm
Lower unit held 7 PSI for 7 seconds (full 10 min)
Fuel connector on engine side tested at 4 PSI for 7 seconds ( full 10 min)
Compression was 50-52 PSI with decompressor on
Full water pump job w/thermostat
Grease points
Throttle cables adjusted
New fuel lines and filter (Hard and old)
New fuel pump (diaphragm etc... hard and old)
New pet **** (Fitting broke off)
New fuel check valve (sticking)
New tank and cap (cracked around cap area)
New thrust rod (owner lost)


Thank you for your help so far. Every bit helps.

Thank you,
DamianJP