Tohatsu M8B Lower Unit

[Ducker17]

Hi all,

I have a 20 year old Tohatsu M8b 8 horse outboard. It had a crack in the prop shaft housing and some other issues that were fixed with some JB Weld. It also would grind it reverse so reverse was unusable for the last two years. Today when cruising at full throttle the forward gears stopped working and barely spun the prop. Is this an issue that would be fixed by replacing the entire lower unit? I am not an expert with outboards or anything so I was hoping some of you here at iBoats could help me.

 

[pvanv]

Why mess with the prop housing? They are available new, cheap.

3B2Q601011

HOUSING, PROPELLER SHAFT

$39.80

Yes, you COULD replace the LU. Would need to know shaft length (S, L). But that's a bit expensive:

3B2Q873027

LOWER UNIT ASSY LONG 8B-9.8B

$691.75

Better to drop the LU and disassemble it to see what's wrong. Could be the clutch or a gear issue... or just the linkage.

For that matter, you may just have spun the prop hub. If the prop shaft turns OK, and the motor works OK at slow speed, but seems to not go fast, you probably need a new prop.

 

[Ducker17]

Paul, sorry about the pretty confusing first post, I was in a near delusional state from exhaustion. We messed with the prop housing because it was in the middle of the hunting season and we couldn't wait for the new part to get in.
Today we took of the prop and it looks like a rubber seal in it is absolutely shredded, is this a sign of spinning the prop?

Also, what parts would you think I would need to get the reverse working again? It grinds whenever we shift into the gear, and it is also very hard to find neutral some days when starting the motor, as well as it will occasionally start in forward.

Thanks for your time.

 

[Ducker17]

Paul, by the way it is a short shafted outboard.

 

[pvanv]

Probably need a new prop. Sounds like you are not going all the way into R. Likely bent linkage.