Can't get lower unit back on Tohatsu 6hp - Help!

I took off the lower unit on a Tohatsu MFS6 to inspect the impeller, and now I can't get the drive shaft spline to go back in. I read many other threads where people had this problem, and I have the service manual including diagrams and instructions, but nothing has helped.

I can get the lower unit to within about 1 1/2 inches and then the drive shaft hits something with a clunk. It's not the shift linkage hitting, and it's not the water uptake tube (that's about 1/2" away from the water pump housing gasket). I've tried wiggling the lower unit every which way, turning the flywheel, turning the prop with gear in reverse, and in fwd, and have tried the engine shift linkage in reverse, neutral and fwd.

Very frustrating and now my engine is out of commission while cruising! Checking the impeller should be a simple thing. Anything else I can try to get the drive shaft in? If it matters, I have the engine in the inclined position so that I can work on it. I don't really have enough room to have the shaft vertical while inserting the lower unit.

Vertical is always better. But, you are clearly hitting the head of the block. It's a "feel" thing; no way to describe it; this is with any brand of outboard. Have a cuppa and try again. Always works for me.

pvanv said:

But, you are clearly hitting the head of the block. It's a "feel" thing; ....

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Yeah, that's what I figured. If I'm hitting the head of the block, you mean that I'm missing the black metal guide tube below the spline teeth in the engine body right? I just don't see how I could be missing that every time, because I've tried 30+ times over the course of 3 hours, with the drive shaft at every possible angle.

I'm going to try to get a mirror and flashlight in there, but I think I really need to invest in one of those fiber optic scope camera thingies.

Again, it's a "feel" thing. Works best with the motor vertical.

Good news, my wife managed to do it! She tried for 20 minutes with no luck and was about to give up, and then suddenly it just worked. No idea what was different (other than having a different person try it!).
Two things that *might* have helped were rotating the engine so that the port side of the leg was down, and the other was pulling out the rubber gasket that seals the top end of the shift rod (this gasket might have been getting in the way before - there's only about 1/4" difference in movement between the point where the drive shaft was hitting and where the shift rod hits after that).

I'm having the same issue. 2 hours, and still can't get the lower unit back on. If it's a 'feel' thing, I just don't feel it. Will try again tomorrow.

Just had same problem yesterday. Took two of us to get in after 5-6 trys , first make sure that shift shaft is turned to hole opening on starboard side, you have to hold shackle down with flat screwdriver, then shiftshaft has to go through little hole up above . little 10mm bolt has to be facing hole on starboard side. When you get shift shaft through small hole , you'll be about 2 1/2 in.from then pull hand crank slow and it should move up. It a pain in you know what .but those motors are quite and start rite up.

And now you know why OB mechanics charge $100 an hour.

We got another 1 , came in on Friday don't know what's wrong with it yet.

Little edy bidy had 70 psi compression.