Alpha one outdrive gearbox rebuild question

[Jgcrock99]

Good afternoon,
I have a 1995 Chaparral with the Gen ii alpha one drive. Ive had a gear lube leak in the outdrive and am attempting to do some seal replacement on my own but had a question. I've got the top plate off the outdrive and noticed the vertical shaft has a good wobble to it and I wanted to know if this is normal or means bearings need to be replaced. I see the top bearing rides in a race at the top of the shaft but when I grab the bearing I can move the entire shaft pretty good. All the gears have almost no wear but I'm having to replace these oil seals and wondered if the bottom bearing might need replacing if it has play in it. Thank you. The leak I had in the drive had gear oil coming out the water pick up holes so I was planning to replace all seals in the vertical shaft. I'm a newbie to this type of repair so thank you for your help.

 

[Bt Doctur]

oil from the drain holes does not mean the upper seals were the problem and most likely is the seal in/under the water pump base.Alpha 1 or the alpha 1 GEN II are both easily replaced. The play in the upper shaft is normal with the top cap off,
There are 2 seals in the upper , input shaft is replaced by removing the input shaft ,removing the nut and bearing package,removing the seal carrier and knocking out the old seal and pressing in the new one. The seal under the vert shaft is replaced by knocking the seal upward and out and the new one downward and in till seated.

Mercury Mercruiser #6 Service Manual Sterndrive Units R-MR-Alpha One-Alpha One SS [PDF, ENG, 16.7 MB].pdf

drive.google.com

 

[Jgcrock99]

So when I removed the lower unit to investigate the issue, the vertical shaft all the way to the spline was covered in oil, this is why I was looking to replace the seals there. Is this inaccurate? Could it be something else? I was told the splines should not be in oil so the fact that it was present on the shaft meant the seals were bad. Someone has mentioned a vacuum test for this unit but not sure how to perform this. Thank you!

 

[Scott06]

So when I removed the lower unit to investigate the issue, the vertical shaft all the way to the spline was covered in oil, this is why I was looking to replace the seals there. Is this inaccurate? Could it be something else? I was told the splines should not be in oil so the fact that it was present on the shaft meant the seals were bad. Someone has mentioned a vacuum test for this unit but not sure how to perform this. Thank you!

if i recall correctly on a gen 2 the vertical driveshaft is what makes the oil seal on the upper, so unless the gear lube was there before you pulled it apart the lube may have gotten there when you pulled it apart. @Bt Doctur would know for sure

I would clean it up put the halves back together and pressure test it. If you remove the water pump I think you can spray soapy water on drive shaft seals in the upper and lower.

There is a sticky section at the top of the mercruiser forum and in there should be a thread or two on how to build a pressure tester and how to do the test.

When I re-sealed mine last year after catching a fishing line on the prop seal, the only seal that was bad due to age/wear was the shift shaft seal. Would recommend getting the shift shaft seal in the plastic housing vs just the replacement seal as I couldn't get the new seal to seal against the plastic housing...

Get the factory gen 2 manual ( I think #14) as it is an invaluable resource