Drive shaft to crankcase alignment

Hi. I ran into a problem when
reinstaling a lower unit back to the crankcase... The drive shaft doesnt line up with the hole in the crankcase, its about a half inch out,, I can still
get it in there but have to push it fairly hard.... The drive shaft isnt bent cause wen i spin it, it doesnt wable.. I noticed that the water pump housing
is a little off wich i think is causing the leg to be slightly bent (where it bolts together, one side sits a little higher.. circled in pic) Do you know
if this is allowable, or is it something i need to fix? Im worried about wearing bearings and splines. I think its been running like this for 50 years, cause i dont know what i could have
done to cause it.. I couldnt find anything on the net about it, so i thought i would ask your opinion,

Re: Drive shaft to crankcase alignment

I suggest that you remove the lower unit, then remove the driveshaft. Now, slide the driveshaft by itself into the powerhead, lining up the driveshaft splines with the crankshaft splines. You can then observe the angle of attack so to speak, the alignment of the driveshaft in relation to the center of the long exhaust housing.

The picture I get from what you've said is that as you slide the lower unit assembly up into the crankshaft splines, one side of the top surface of the lower unit is 1/2" away from the surface of the exhaust housing while the other side is touching. This just doesn't sound possible to me.

Really sounds like you're missing the crankshaft splines altogether.

Re: Drive shaft to crankcase alignment

That does sound very odd?
Sounds like a upper/lower motor mount problem?

Re: Drive shaft to crankcase alignment

If your motor is a 70s 6hp, there is a cross-pin in the upper end of the driveshaft that needs to enter into a mating slot below the crankshaft spline. This crosspin pushes the lower crankshaft seal up making the seal function. It sounds like you may not have gotten the crosspin into the slot if this is the motor.

Re: Drive shaft to crankcase alignment

Here are some better pics, in the first picture, if i leave that gap in the housing than the shaft lines up with the crankcase but if i bolt it tight the shaft ends up a bit off from the hole in the crankcase. I am able to install the lower unit to the crankcase and everything else together. But there will be a constant side pressure on the shaft if i leave it the way it is... i think the leg must be bent.. any ideas how to straighten it or could i stick some kind of shim in that gap of the housing. the second pic just shows where the drive shaft is... off to the side instead of centered.

Re: Drive shaft to crankcase alignment

Good picture, explains everything. That is normally caused by a out of line (bent) exhaust housing (hsg between lower unit & powerhead). This is a common problem when a engine is hit hard or dropped.

This happens even on the higher horsepower engines also.

The cure.... replace that housing. Eventually it results in a broken driveshaft. Strange that it's lasted for so many years.

Re: Drive shaft to crankcase alignment

Thanks everybody for the advice,, i will pull the lowere unit apart and see if i can straighten it

Re: Drive shaft to crankcase alignment

I looks like material is missing on the lower flange(upper photo). That makes it pullup at an angle when you tighten the bolts. Would this not need to be welded and remachined? or just replaced? or can you take a fly cut at a machine shop to get this surface back "square"?