Shift shaft seal / carrier seal / oil o-ring?

[JonBoat55]

New gear oil leaking out of the lower unit holes after putting the out drive back together. Which seal is to blame?
Water was flowing out of holes when running on the hose. Drained oil after seeing the leak, no water in oil.

 

[Scott06]

New gear oil leaking out of the lower unit holes after putting the out drive back together. Which seal is to blame?
Water was flowing out of holes when running on the hose. Drained oil after seeing the leak, no water in oil.

most likely the carrier seal below the water pump. relatively easy to split the drive remove the water pump and pressure test the lower by plugging the hole where the quad ring goes. Usually can clamp a flat piece of metal on it.

Get 12-15 psi of air pressure in there and put soapy water on seals. Shift shaft would leak outside the drive in the front not where this is leaking.

 

[JonBoat55]

Split the drive and found the shift shaft assembly soaked in oil. Pressure tested and found the leak in the oil bushing gasket. Just installed the part two days ago. Serves me right installing Sierra parts.
I can see that oil coming out of those weep holes could be either the shaft assembly or the carrier shaft leaking. I'm going to make sure the carrier shaft tests OK before putting the drive back together, that was also a new part I just did.

 

[Scott06]

Split the drive and found the shift shaft assembly soaked in oil. Pressure tested and found the leak in the oil bushing gasket. Just installed the part two days ago. Serves me right installing Sierra parts.
I can see that oil coming out of those weep holes could be either the shaft assembly or the carrier shaft leaking. I'm going to make sure the carrier shaft tests OK before putting the drive back together, that was also a new part I just did.

I tried just replacing the seal on the shift shaft not the whole plastic housing it is in, could never get the seal to to stop leaking , ended up buying the bushing with the seal in it.

Sierra is better than most aftermarket parts, but the OEM is best in my experience. My boat is a 2004. two years ago I caught a fishing line on the prop shaft so while I had it apart I figured I'll reseal the drive, if the new seals last as long I wont own the boat when they need it again...

Same with impellers I have found the gen 2 OEM impellers to last well over 6 years. I changed mine at 6 years no issues, my neighbors was 11 years old also no issues.

 

[JonBoat55]

I'm kicking myself, my boat is a 99. I've had it for six years with no issues, this season I decided to do some extra maintenance and do the shift shift assembly and carrier assembly, Have never had oil leaks before and now I do.

 

[Scott06]

I'm kicking myself, my boat is a 99. I've had it for six years with no issues, this season I decided to do some extra maintenance and do the shift shift assembly and carrier assembly, Have never had oil leaks before and now I do.

no good deed goes unpunished... On my entire drive the only seal that was somewhat compromised by wear/age was the shift shaft seal. All other seals were in nice shape, except for the prop shaft seal with fishing line...

So you had no leaks - just replaced the seals while you were in there?

 

[JonBoat55]

no good deed goes unpunished... On my entire drive the only seal that was somewhat compromised by wear/age was the shift shaft seal. All other seals were in nice shape, except for the prop shaft seal with fishing line...

So you had no leaks - just replaced the seals while you were in there?

Correct. I figured worst case, I'm wasting a bit of money for the sake of preventative maintenance. Nope, that wasn't the worst case haha

 

[JonBoat55]

What would be the direct issue of gear oil seeping down the upper shift shaft onto the lower shift shaft assembly?

 

[Scott06]

What would be the direct issue of gear oil seeping down the upper shift shaft onto the lower shift shaft assembly?

do you mean you have lube leaking down the shift shaft in the bellhousing onto the lower ? This may be from the poppet valve in the gear lube line. If you dont pop the drive on quickly any residual lube in the line will leak out when the drive is an inch or so off the bellhousing.

 

[JonBoat55]

do you mean you have lube leaking down the shift shaft in the bellhousing onto the lower ? This may be from the poppet valve in the gear lube line. If you dont pop the drive on quickly any residual lube in the line will leak out when the drive is an inch or so off the bellhousing.

Understood. Thanks for all the info and responses back by the way as I work through this. Pretty quiet in here lately.

 

[Scott06]

Understood. Thanks for all the info and responses back by the way as I work through this. Pretty quiet in here lately.

normal this time of year, goes dormant unless someone has a project going.

If you dont have it get manual 14 for the gen 2 drive very helpful/good info