Prop Shaft Housing Replacement

[TheKid]

30 miles off shore last weekend we hit something. I thought it was a furbag but not sure.

10 miles later the prop gives and spins. Luckily had a spare. While removing the spun prop I must have dropped a spacer in the drink because after at the launch ramp you can see the prop gouging into the housing. No, I did not feel a difference in performance, well not a real noticeable one as this prop is a different pitch.

20 miles at 3500rpm did a number on it. The seals are still good but now the prop no longer sits inside the housing and there is a 5 mm gap between the housing and prop. This is not something I want to risk and need to change out the housing.

I'm wondering if anyone has done this. It appears simple, pull the housing, replace and check shims for fit, replace shim if neccesary and bolt up again.

Does that sound right? It's what the manual states.

The manual doesn't state how many "Oh " "WTF" and "God Damits" it takes.

Anyone???

FYI, the housing can also be called a bearing carrier if that clears anything up.

[Boatdood]

What is not clear at all is which engine you have. The procedure you outlined is pretty much it, but it's a lot like riding a bike. Most of us don't get it just right the first try. I've seen what you described quite a few times. What is surprising is that it lasted 20 miles and still held together.

[seabob4]

Possible LU disassembly?

[Blue Agave]

Is it a Mercury?  I have a Mercury "Gearcase" that I'd be willing to sell.  Fyi - it is just the case, no gears or shaft.

[TheKid]

My apologies, its a Tohatsu M140A2.

Possible LU disassembly?

Not sure I understand?

[seabob4]

My apologies, its a Tohatsu M140A2.

Possible LU disassembly?

Not sure I understand?

LU disassembly.  The lower unit.  It depends if the bearing carrier can be removed, as well as any seals and shims, through the gearcase hub.   If there are any retaining screws that have to be accessed from the inner portion of the gearcase, then you have to pull the LU and take it apart.

Sounds like, from what you have described what the service manual tells you, that it can be done exteriorlly...

[TheKid]

OK, so I popped the housing out. Yes Bob, it's a separate assembly. Everything seems straight forward.

The only thing I am worried about now is the shims and how to make sure I have the right ones in. I'm assuming the shims are to take up the slack in tolerances of the housing, bearings and gears. I could just use the same ones, however, that might not be the right way to go. Manual states special tools required to adjust and I just don't have them nor the cash to get them. I figure a little wiggle this way and a little less wiggle the other and I'll be set.

Kidding of course, I'm sure I'll figure something out. It takes me a few reads and actually handling the parts to understand the manual sometimes. Else fails, the local shop will make some cash. I say some cause I've done most the work.

Usually, I need to talk to others about my problems and in the process I end up figuring it out myself or getting great advice. So, I appreciate the help and just plain listening.

Until next time....when the parts arrive...Derby Out!

FYI, the warm water is getting closer. I really need to figure this out quick...with safety in mind of course.

[TheKid]

So, I got everything back together tonight and ready for the pressure test when I noticed something to make me uncomfortable.

In shifting gears, when in neutral the prop spins free in both directions, good. In both forward and reverse it locks in both directions bad. If memory serves is should spin clockwise with a ratcheting sound when in forward and I think both directions is reverse.

Is that right? It's what I'm thinking.

So, with dark and frustrations I decided to put it up for the night before going forward with anything else.

What do you think?

Manual states nothing except to rotate the drive shaft and see which way the prop spins. I didn't take the lower unit off, so this is not an option...yet.

[seabob4]

I'm not going to say this is normal, but after every water pump/impeller replacement I do, I make sure that the shift shaft is aligned properly by doing just what you described.  N, spins freely, F, only CW, R, only CCW.

Can't hurt to fire up the motor on the muffs and see what's going on when you shift...

[TheKid]

So, I'm not crazy. Before I do, I'd like to figure out what could cause this. if nothing comes up, I'll fire it up.

What exactly is the ratcheting? In gear the bevel and pinion gear should be engaged. I don't see how it could slip/ratchet.

[TheKid]

Anyone else with a Tohatsu can confirm whether or not these have a slip clutch, meaning in Fwd gear rotating prop by hand it slips one way and locks the other?

I'm stumped.

[fitz73222]

The ratcheting is caused by the clutch dog face that resembles a saw tooth configuration mating into the forward gear face. The reason it ratchets is that the clutch dog is spring loaded to ensure proper mate up when shifting. When the crankshaft is turning clockwise the clutch dog and forward gear are locked together. If you rotate the propeller in the direction opposite its normal rotation while in forward gear it will ratchet and it is quite normal. Now I am speaking for Mercury geartrains and I would assume the Tohatsu is a similar design. You should not have any ratcheting in reverse gear and the propeller should be locked if you try to spin it in either direction. I hope this makes sense but the intent is to tell you that you dont have a problem assuming you reasembled everything correctly.

[TheKid]

Thanks Fitz. I was assuming the same, that it was similar to a Merc.

However it is not. The dog has square gears.

This was confirmed by a few Tohatsu Techs on the iBoats forum.

We are good to go.

Thanks for listening!!!