Alpha One Gen 1 - remove from boat or not in order to replace water impeller

[Blueghost924]

I need to replace the water impeller from my Alpha 1 Gen 1, and the sterndrive is still installed. I've heard of people removing the entire sterndrive to get to the lower unit for the impeller replacement, and I've seen where folks raise the sterndrive and simply remove the lower unit (while leaving the upper still installed). All 3 bellows are brand new and the gimbal bearing is new (I've had them recently by a local marine mechanic).

Is it recommended I remove the entire sterndrive or just drop the lower unit from the upper while leaving it still installed to replace the water impeller? If I just remove the lower unit only, is it still necessary to put it all the way in forward? Thanks.

 

[khe]

When I did mine (Alpha 1 gen 2), the drive was off the boat as the boat was in winter storage and the drive was on a stand in my basement. In my opinion, it is easier to remove the upper gearcase with the drive on a stand vs. trying to wrestle the lower gearcase to mate it to the upper gearcase while mounted to a boat. Others may have a different opinion.

 

[Rodney Williams]

it's easier to remove the drive and replace the water pump. getting the pickup tube aligned will be much easier if the outdrive is off.

 

[Bondo]

If I just remove the lower unit only, is it still necessary to put it all the way in forward?

Ayuh,.... Whether ya pull just the lower, or the whole drive, All of the Alpha series of drives are shifted to forward, before doin' anything to 'em,...

 

[ziggy]

Is it recommended I remove the entire sterndrive or just drop the lower unit from the upper while leaving it still installed to replace the water impeller?

when i got my 1st i/o. i'd just remove the lower to do the impeller. while just doing the lower to remove is ok. putting it back i found challenging to say the least. painful even. then i started pulling the whole drive to do the impeller. especially after i got an alignment bar as i wanted to use it. doing the impeller on the bench is much easier imho. while not real easy to put the whole drive back on, it's way easier than just putting the lower back onto the upper while the upper is still attached to the boat. + as a side benefit ya get to run yer alignment bar and lub your coupler, recheck your gimble brg. for smoothness, lub your ujoints, lub your shift slide and shaft and inspect generally.
so i recommend pulling the whole drive. get an alignment bar, build a drive stand. imho, it's the way to go.

 

[Oshkosh1]

I've also done it both ways and removing the entire drive is much preferable.

Now, to I'll also say that it's easier to remove the lower unit while the upper is attached as well. I use two "Workmate" benches which hold each half seperately and after I've replaced the impeller I'll attach the upper to the lower and then install as a whole.

I also like to take a peek at the alignment/gimbal while the upper is off as well as being able to lube the U-joints and the spline.

 

[Blueghost924]

Thanks for the info, and I'll definitely remove the entire drive to make it easier. When the local shop performed the work, they did check alignment along with replacing the gimbal bearing.

I'm pretty good mechanically, but I've never replaced a sterndrive water impeller and housing so I don't know how hard it will be. I plan on following the shop manual and reviewing the videos - but any tips would be great.

 

[khe]

I would drain the gear oil from the drive before removing it from the boat.

 

[Blueghost924]

Funny you mention draining the oil before removing...I did that figuring it would make it easier.

 

[Baylinerchuck]

When you separate the upper from lower leave the linkage in forward position and turn the prop slightly to release the linkage. The water pump is an easy repair. Lining up the impeller with the shaft key can be challenging. Separating and joining the halves can also be a little tricky.

 

[Bonus Check]

If all you're doing is replacing the impeller, I recommend that you only drop the lower to do so. There is no need to remove the entire sterndrive as you just had all of that replaced in the upper. Putting the lower back onto the upper is very simple. Get the water alignment tools. It cost a couple of buck as it is sacrificial. Takes about and hour or so to replace the impeller when you only remove the lower.