Outdrive oil leak..

[targabill]

Trying to figure out where: 1988 Mercruiser Alpha 1
Boat on trailer, outdrive up, I see oil on the connection point of the Shift rod. The point you line up by putting it in forward to remove outdrive. Very odd as that shaft goes into the exhaust area.
Anybody see this? And where could it be leaking from?
Hard to see the oil but right above the rod slot for shift rod..

 

[Chris1956]

What kind of oil is it? I presume gear oil, but you need to verify. If it stinks like rotten eggs is it gear oil.

I presume your OD is Gen 1? If so, the only source of gear oil is the seal between the upper and lower gearcases. maybe the gasket has failed?

Alternatively, maybe the yoke leaks gear oil into the driveshaft bellows and that in turn found it's way to the shift shaft? That is a guess.

If the oil is motor oil, you need to look at the engine block, I would think.

 

[targabill]

What kind of oil is it? I presume gear oil, but you need to verify. If it stinks like rotten eggs is it gear oil.

I presume your OD is Gen 1? If so, the only source of gear oil is the seal between the upper and lower gearcases. maybe the gasket has failed?

Alternatively, maybe the yoke leaks gear oil into the driveshaft bellows and that in turn found it's way to the shift shaft? That is a guess.

If the oil is motor oil, you need to look at the engine block, I would think.

Hi, Thanks,
I pretty sure it's gear oil. How would motor oil make it's way back there? Through gimblet??
Mine is a Gen 1, is there a way to tell?

The seal between upper/lower case is below the leak so it not that..

 

[Chris1956]

I have no idea how motor oil would make it's way there, however, motor oil should be exclusive to the engine.

Check the driveshaft bellows for gear oil. I don't know exactly how it would get to the shift shaft, but outside of some sort of a crack in the OD casting...

 

[kenny nunez]

A good chance the seals in the lower area of the drive shaft housing is the leak.
Drop the lower, if there is oil on the vertical shaft then that is the leak. There is a lower seal that usually comes apart exposing the upper seal area, since the lower gear extension is plain steel it will be pitted and require a 1.250 speedy sleeve to repair the surface. You will have to remove the rest of the drive and completely disassemble the drive shaft housing.

 

[targabill]

A good chance the seals in the lower area of the drive shaft housing is the leak.
Drop the lower, if there is oil on the vertical shaft then that is the leak. There is a lower seal that usually comes apart exposing the upper seal area, since the lower gear extension is plain steel it will be pitted and require a 1.250 speedy sleeve to repair the surface. You will have to remove the rest of the drive and completely disassemble the drive shaft housing.

Thanks Kenny,
The drive shaft in the lower unit goes through the water pump.Are you thinking below the water pump? There is an O-Ring on the upper side of that shaft..
Does anybody know how the gear oil gets from the lower halt to the upper half, I just can't see the port for that, on pictures..

 

[04fxdwgi25]

Item 6 is the oil passage o-ring seal

 

[Scott06]

Thanks Kenny,
The drive shaft in the lower unit goes through the water pump.Are you thinking below the water pump? There is an O-Ring on the upper side of that shaft..
Does anybody know how the gear oil gets from the lower halt to the upper half, I just can't see the port for that, on pictures..

the seal in the upper that seals the vertical driveshaft in the bottom of the upper unit. Common for that seal to go and leak gear oil down the shaft.

 

[targabill]

the seal in the upper that seals the vertical driveshaft in the bottom of the upper unit. Common for that seal to go and leak gear oil down the shaft.

Thanks,
I was just watching a youtube on rebuilding the upper unit and I was thinking that might be the seal in question..
That looks like a big job to replace... Can it be replace from the bottom and not remove the whole drive U-Joints and shafts ??

 

[targabill]

Item 6 is the oil passage o-ring seal

View attachment 399447

Hi, Thanks.... Do you have a link to where you got this Exploded View ??

 

[Scott06]

Hi, Thanks.... Do you have a link to where you got this Exploded View ??

MerCruiser Engine & Stern Drive by Engine Model

Lookup MerCruiser engine & stern drive by engine model and buy discount parts and accessories from our large online inventory.

www.marineengine.com

these are the parts diagrams I usually use. While i try to support our host site here with parts purchases, their parts look up is painful...

the photo you sent of the lower is an earlier MC1 lower as shown by rounded cav plate and i think the preload pin on driveshaft. It is likely mated to a Alpha gen 1 upper as these drives you can mix and match... but it may cause an issue for you ordering parts.

I dont know if the drive shaft seal comes out through the bottom or you need to tear down the upper like on a gen 2. If you do have a leak I would drain and pressure test the drive as likely you will have other seals that should be replaced to considering the age.

 

[04fxdwgi25]

Hi, Thanks.... Do you have a link to where you got this Exploded View ??

Sent you a PM

 

[nola mike]

Thanks,
I was just watching a youtube on rebuilding the upper unit and I was thinking that might be the seal in question..
That looks like a big job to replace... Can it be replace from the bottom and not remove the whole drive U-Joints and shafts ??

No. Need to remove everything. Not too horrible though. As Scott said, you have an mc-1 lower. Not sure if the mc-1 upper and alphas use the same seals, or which your upper is. Also as Kenny said you'll likely need to speedi sleeve your drive gear

 

[targabill]

No. Need to remove everything. Not too horrible though. As Scott said, you have an mc-1 lower. Not sure if the mc-1 upper and alphas use the same seals, or which your upper is. Also as Kenny said you'll likely need to speedi sleeve your drive gear

Thanks, Never used a speedi sleeve, do marina's sell them specific for each
shaft.

 

[kenny nunez]

You can get them at any bearing supply or NAPA. Also if you google Speedy Sleeve you will be able to look at their catalog.

 

[targabill]

You can get them at any bearing supply or NAPA. Also if you google Speedy Sleeve you will be able to look at their catalog.

Thanks again, I did go to the speedisleeve web site, they go by exact measurements, is this info somewhere? The NAPA we have here is terrible, not to smart a people working there..

 

[targabill]

No. Need to remove everything. Not too horrible though. As Scott said, you have an mc-1 lower. Not sure if the mc-1 upper and alphas use the same seals, or which your upper is. Also as Kenny said you'll likely need to speedi sleeve your drive gear

Just an FYI to anybody following this oil leak:
Turns out you can change this Lower oil seal in the Upper Unit by just removing the lower Unit and Upper unit left on the boat.
Pop lower unit, like 15 min.
Pull out oil seal with a inside Bearing remover, like 5 minutes..
Lock Tight, new seal, reinstall lower unit, Back in business..
About an Hour and a half, took 2 with me replacing the impeller as well.

I plan on doing all the seals over the winter, but this fixed my leak..

Happy Boating!!

 

[nola mike]

If it was leaking it means both seals were bad. I can't remember off hand why the upper would need to be changed though if the lower has been replaced.

 

[Scott06]

If it was leaking it means both seals were bad. I can't remember off hand why the upper would need to be changed though if the lower has been replaced.

Not sure if one seal keeps water out other seal keeps oil in?

 

[nola mike]

IIRC the area between them is normally dry. the lower is exposed to water on one side and the upper to oil. If the upper fails oil will fill the cavity whereas if the lower fails water enters the cavity and rusts the gear. On mine the gear needed a speedi sleeve on one of the surfaces.

EDIT: I feel like @kenny nunez had some info about this, he was talking about the back to back seals in another thread.

EDIT 2: Ha, didn't see he was already on this thread