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MerCruiser Alpha I, Gen II, Lower Unit Re-install Question

Posted By: Budinski

MerCruiser Alpha I, Gen II, Lower Unit Re-install Question - 03/22/19 02:10 AM

I just replaced the impeller in my MerCruiser Alpha I, Gen II, and am now at the point of reinstalling the lower unit to the upper part. When I separated the two parts earlier, it was in neutral. When I was joining them, I watched as the "L" shaped arm fit into the shifter cable fitting. With the 4 main mounting bolts installed snugly, and without refilling the crankcase oil, and with the engine off, I shifted it into forward. The prop wouldn't turn one way (good), but when I turned it the other way, it DID turn and it made the "L" shaped arm jerk (kind of like a ratcheting movement). When I shifted it into reverse, the prop stops when trying to turn it the other way, but it "ratchets" while turning it the opposite way.

I don't think this is normal. Before this maintenance, I "believe" that when it was in gear (forward or reverse), it didn't turn at all [meaning it didn't do that ratcheting movement].

Also, when my lower unit is on the bench with the driveshaft sticking straight up, when I move the "L" shaped arm into forward or reverse, I cannot turn the crankshaft to make the prop turn. Is that normal?

Any advice would be greatly appreciated!

Bud
Posted By: Budinski

Re: MerCruiser Alpha I, Gen II, Lower Unit Re-install Question - 03/22/19 02:49 AM

I just put a rag around the splines and put a vice grip on the rag, and I can turn the crankshaft which turns the prop just fine. It is smooth and appears to be fine.
Posted By: Frantically Relaxing

Re: MerCruiser Alpha I, Gen II, Lower Unit Re-install Question - 03/26/19 02:07 AM

Far as I know, all Merc drive's prop shafts spring load the moving gears into "forward" position whenever the shift mechanisms are divorced and the drive is 'at rest'. In forward position the long tab on the shifter rod aims straight front to back, so whenever joining the 2 halves, your shifter should be in forward position so the line up smile
Posted By: Budinski

Re: MerCruiser Alpha I, Gen II, Lower Unit Re-install Question - 04/01/19 01:07 AM

Thanks. I got it re-installed, and the driveway run looks good. I will feel better when I get it in the lake--perhaps next weekend. I'll try to post a picture of the "before-and-after" impeller position.
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