Alpha One Gen 2 drive won't hold pressure - where to check for leaks?

JASinIL2006

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Trying to get the boat ready for the summer. I have drained the gear lube and was pressure testing my A1G2 drive before refilling. Over the winter, I did nothing to it (except drain the lube) and it sat in my basement.

I pumped the drive to 10 psi and let it go about 10 minutes. I turned the drive shaft, prop shaft and shift rod, and noted no change. It held steady for 10 minutes.

Then I increased pressure to 15 psi and let it go about 15-20 minutes, again moving the shift rod, drive shaft and prop shaft. After about 20 minutes, I noticed it had dropped pressure about 1/2 psi. I let the pressure out, and retested at 15 psi, and now the pressure is dropping perceptibly; I can watch the dial and see it very slowly losing pressure (e.g., about 3.5 psi in 5 minutes).

I tested (with soapy water) the lower drain hole, the upper vent hole (where my tester is installed), and all the connections on the tester itself, with no bubbles showing. I tested around the top cover and the four screws that hold it on, and around the shift rod (where it sticks up out of the lower part of the drive). I also put some soapy water around the prop shaft, where it emerge from the drive and the thrust hub fits, No bubbling at any of these spots.

I'm not sure where else to check; I know there are other seals, but I'm not sure how to properly check to see if they're leaking.

Can anyone point me toward where to check any remaining seals? Am I right in thinking a seal is bad? Any idea why it held pressure for a while but now is leaking badly?

Thanks for your help!

jim
 

harringtondav

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^^^^ +1. I rigged up a bicycle pump pressure tester years ago. I didn't know 10 psi was the limit. Before reached 20 psi I heard a hiss and lost all pressure. The oil seal carrier BT mentions was pushed up out of it's bore.
 

sickwilly

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That is where my leak was. I plan to replace the carrier seal every other impeller from now on. You use two screwdrivers to pop it up. Pull the seal out of the old one, and use it to pound the new one in place.
 

JASinIL2006

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Just to make sure I’m looking at the right thing, this is where I should look (first pic) and I’m checking the seals in the oul seal carrier. Is that right?
 

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JASinIL2006

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Ok, so I split the drive and pulled the water pump housing and oil seal carrier. I didn’t notice anything dislodged or out of place, and I don’t see any apparent problems with the seals (see pics below).

I was pressurizing the drive from the top (vent plug hole) rather than the bottom drain plug hole. Would the oil seal carrier still be suspect?
 

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JASinIL2006

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Replaced the water pump, oil seal carrier, etc., and now the drive holds10 psi no problem! I was about due for a new impeller, so I should be good for a couple more years....
 

achris

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In future, don't leave the drive empty, fill it with new gear oil before storing it...

Chris.........
 

JASinIL2006

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Also, I noticed that the water pump kit I ordered (OEM MerCruiser Alpha 1 Gen 2 Water Pump/Impeller Service Kit 817275Q05) had the two separate gaskets that sit on either side of the water pump face plate. I ordered the exact same kit (same part number, same vendor even!) several years ago, and that kit had the single face plate with an attached rubber gasket; no paper gaskets at ll.

Did they abandon the one-piece design? I had assumed the one-piece plate was a new, improved version of the old paper gasket approach.
 

CamaroMan

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check the upper yoke seal, its a very common leak area - having said that since you are so deep, just replace them all except the prop seal and retest - make sure no grit on shift rod at seal area, sometimes calcium builds up there.. upper yoke seal is a very common leak area too - rotate it a few times.. pressurize it in a inflatable duck pond and check for bubbles -
 
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