Alpha One 1988 upper driveshaft housing oil seal question

[Watermann]

Drive unit # 0B659782

After my first outing I checked the gear case oil and found it didn't look right like a small amount of water was mixed in. I pulled the drive and split the case. The only place I could find gear oil was around the shift shaft,.

While inspecting the upper half of the drive unit I saw there was a mangled up spring and rotten rubber of a seal in the bottom edge of the driveshaft pocket. It had obviously not been functional for many years.

My question is can I pull the old seal out with my puller and seat the new seal in from below, the manual shows putting it in from the top of the gutted housing ... part #10 96503 1 — SEAL, Oil, DRIVE SHAFT HOUSING - LOWER? Thanks in advance fellas, was something I hadn't come across yet. Kind of wondering if it's even needed after seeing it's not been in usable shape for a very long time with no ill effects.

 

[Rick Stephens]

There are two seals there, one faces the spring up to keep oil in, and the other faces the spring down to keep water out. I believe you have to pull the yoke bearing assembly out the front, then remove the cap and remove the upper gear shaft to access the seals. You drive the lower seal out the bottom and drive the upper seal out the top. This is detailed in manual #6. Reassemble in reverse order. Only special tool is the spanner wrench for the bearing carrier behind the yoke and appropriate seal and bearing drivers.

 

[Bt Doctur]

#11 has to come out from the inside, #10 comes out from the bottom, use a 1/2 drive extention and a socket on backwards to seat the seal flush

 

[achris]

You're only replace seal #10. With a screwdriver (fairly big ) in through the exhaust cavity (assuming the drive is off the bell housing) you can flick the remnants of the oil seal out, and using the right size socket and a 300mm extension, knock the new one in.

I videoed when I did it when servicing an Alpha One water pump. Video in the link at the bottom of my signature.

Chris.....

 

[kenny nunez]

Take a very close look at the seal running surface of the lower driven gear. Most times when the l#10 seal fails it causes the seal surface of #11 to rust and pit the surface. The surface can be repaired with a Speedy Sleeve.

 

[Watermann]

Take a very close look at the seal running surface of the lower driven gear. Most times when the l#10 seal fails it causes the seal surface of #11 to rust and pit the surface. The surface can be repaired with a Speedy Sleeve.

After seeing what it takes to gut the upper and then reassemble everything I can say that is out of my wheelhouse. There's no rust or oil in that driveshaft spline pocket that I can see from below.

I'm going to replace everything shift shaft seal/bushing related for the gear case water leak and replace that lower #10 seal from the bottom end. Also of course a raw water pump kit as well.

 

[kenny nunez]

Before you install the lower seal plug the oil transfer port and try to put about 10lbs of air pressure and see if the upper seal is holding. If that upper seal is not holding plan on a Sea Tow call and a new upper gear set after the next outing.

 

[nola mike]

It's actually not too tough to remove the gear set and bearings, you don't have to do any adjustments (unless you want to do the input shaft seal while you're in there}. I wouldn't stop at that one seal. I was glad I took the rest apart, I had pitting on that lower driven gear that kenny nunez alluded to. Also, Rick Stephens , this is the one case I was talking about a few days back where both seals face the same direction, both spring up (iirc) keeping gear oil in.

 

[Rick Stephens]

It's actually not too tough to remove the gear set and bearings, you don't have to do any adjustments (unless you want to do the input shaft seal while you're in there**. I wouldn't stop at that one seal. I was glad I took the rest apart, I had pitting on that lower driven gear that kenny nunez alluded to. Also, Rick Stephens , this is the one case I was talking about a few days back where both seals face the same direction, both spring up (iirc) keeping gear oil in.

Damned if you ain't right. Been a few years since I did an Alpha 1. The Alpha 1 Gen 2 ihas them opposed, one up and one down.

Alpha 1:

 

[kenny nunez]

The only tool you will need is the spanner wrench to remove the input shaft. Sierra #18-9803. When you do the pressure check if the driveshaft input seal for leaks also, If there was no water in the bellows that shaft surface should be good.
The biggest problem will be holding the housing while loosening the nut. Sometimes the driveshaft does not want to slide out, pry it out with a large screwdriver against the locknut or heat the housing. Be real careful to account for the large shims.
The speedy sleeve should be between $30-$40.
You can do it!

 

[kenny nunez]

A Chris may have a video on the procedure which should be very helpful.

 

[nola mike]

Here's my thread when I did it a couple of years ago...
https://forums.iboats.com/forum/eng...s/10586584-alpha-1-gen-1-gear-lube-leak/page2

 

[Watermann]

Here's my thread when I did it a couple of years ago...
https://forums.iboats.com/forum/engi...ube-leak/page2

I was looking at the manual and the exploded view of the upper I'd imagined having a huge pile of parts strewn out with some precise methods of reassembly. Looks like after the seal replacement that wouldn't be the case and I'd only need that spanner and my 1/2" drive torque wrench to put it back together. Unless I put in a new input shaft seal which would be a good idea if that far into it.