Cannot reinstall lower unit on 1990 150 blackmax

[karnage]

I'm hoping people of the internet can save me from this one. My buddy and I changed the water impeller on my Mercury outboard today. Once we went to reinstall the lower unit, we struggled to get everything lined up. We kept trying and got to where there was maybe an inch or two gap between the bolts and assumed the splines weren't lining up. We turned the shift shaft one notch to put it into gear and allow us to move the prop and align the splines. That got us a little bit farther, but not all the way. There is resistance to the prop, so we know something is lining up. The flywheel even turns, but there is still a half inch gap or so. We used a ratchet strap to hold the lower unit and save our backs, and if I try to force it up there with it, there is a lot of pressure and something feels wrong. We can just about start the nuts onto the bolts. We even took the water pipe off with no different outcome, so it's not that. We can take the whole unit out and retry inserting it completely evenly, turning the prop, sliding it in there but it still wont go all the way in. Any response will be greatly appreciated, please and thank you!​

 

[Dukedog]

first thing ta check is gearcase if your not sure its original.. could be an earlier pre-load case that got put on somewhere down tha line.........

 

[stresspoint]

don't force anything , it should just slide into place if everything is correctly in place , ? is the motor trimmed full up ,this will make life easier

 

[Chris1956]

They do fit tight. Tilt the motor up and wiggle it. Tighten the bolts with fingers only, and you will not ruin anything. I would not think the strap is a good idea.

If she won't go, try dropping the gearcase and re-aligning the driveshaft splines. The exhaust gasket is on correctly?

However, use a needle nose plier to align the shift shaft. You can get to it just above the yoke, and they usually need some movement to fit right. The shift shafts can "ride" up in their bushings. The linkage is the only thing holding them down. Make sure motor and shifter are in neutral.

 

[karnage]

no

don't force anything , it should just slide into place if everything is correctly in place , ? is the motor trimmed full up ,this will make life easier

We tried with the motor trimmed up and down.

 

[stresspoint]

i have what i call a clicker to click the starter to help align the drive spines , usually , as i posted the Mercury gearboxes go up easy if everything set up right , ok , some need a wiggle but for the most part Mercury and Yamaha are easy , so you have an issue somewhere.

as posted above ,make sure everything is in neutral or it will not slide together ,
check that the crankshaft hole is not full of grease , if it is there is no way the shaft will push up .
make sure that the shift rod is located directly onto the shaft , the rod can miss as you locate the gearbox and drive spline ,hence motor trimmed full up.
there is not much more i can think that will stop the gearbox going home.

once it is up far enough ,the nut and washer toward the front should go onto the stud first and only about 3 or 4 threads , then a slight lift (enough to take the weight ) and push inward toward the power head whilst finger tightening the nut should locate the dowel pins to position "but not home ", when the gearbox is in this position you can start all the other nuts .

 

[saltchuckmatt]

Yes, if you greased the top of your driveshaft the shaft will not fully go in because of hydraulic lock....not sure you got that far though.

Everything in neutrual and spin the flywheel while pushing...hopefully you have cleaned up all the studs and bolt holes.

I watch 4 YouTube videos and each one finely turned off the camera then rejoined after getting it back on complaining about what a b**** it was. So your not the only one.

 

[Dukedog]

tha only gearcase that should have any resistance in tha last 3/4 ta 1 inch IF EVERYTHING IS ALIGNED as it should be is tha early pre-load case period....

 

[karnage]

I watch 4 YouTube videos and each one finely turned off the camera then rejoined after getting it back on complaining about what a b**** it was. So your not the only one.

Yes, funny the way you put that.

 

[karnage]

First off, thank you all for all the responses. I took all your comments into consideration. The issue my friend and I had that first night, I'm really not sure what is was. I don't think it was a gasket, I think it could have very well been excess grease up there causing a little blockage. That would explain only half the splines lining up. I went out there yesterday morning and it just seemed to work after at least an hour the previous night. But, I had taken off the water pipe to try to install without it and troubleshoot, so I had to re-do my work with it on and that had another issue. The pipe would bend or tilt forward towards the shaft once it got up to the entrance where it needed to be. I wrapped a rope around the base of the pipe and yanked it back a few times once my friend held it up there, that pulled it back enough to get it up in there and everything else worked great. I could have left this thread to die but wanted to thank you guys and tell you about my conclusion.

 

[Chris1956]

You did use the plastic water pipe extension to align the waterpipe?

If so, Nothing needs to be used to pull the water pipe into position.

 

[karnage]

You did use the plastic water pipe extension to align the waterpipe?

If so, Nothing needs to be used to pull the water pipe into position.

I did use a new white tube with my kit, but I didn't use a new housing for the impeller so I guess it wasn't as stiff as possible.

 

[stresspoint]

+ 1 , if the water tube is offset then it needs to be aligned properly , you should just be able to locate the pipe strait into the white bit as the gearbox goes into place .
with luck it may have self aligned as the gearbox went up , you will soon find out as there will be no water pressure to the powerhead .