Pressure tested LU

[s.a.m]

Ok i have a 1991 Alpha1 GenII 3.0L.....I few weeks a ago i took off my out drive for the winter and i was going to check the gear oil and water came out for a good 10 seconds then the gear oil which was green....i just got my home made pressure tester and tested the lower unit without the upper and put in about 15psi and it held for a good 10min i can see fine really fine air bubbles coming from the shaft seal after spraying soapy water.....So my question is....could this much water enter the lower unit from the shaft seal as the water pump is turning? it doesn't make sense....

 

[GA_Boater]

Re: Pressure tested LU

Barring a crack in the housing, there are five places for water to get onto the lower unit: the two fill and vent seals, prop seal, shift shaft seal and water pump seal. What I should have said isn't water getting in, rather oil to get out and be displaced by water. The water pump housing is pressurized when the drive shaft is turning so if the pump seals are weak water will be forced through the water pipe and into the lower unit. The pumped water is higher pressure than the oil in the L/U so water will fill the L/U eventually because it will force the oil out through any of the remaining four seals. Does that make sense?

 

[Don S]

Re: Pressure tested LU

Was there water in the bellows when you removed the drive? If not replace that seal, and re-do the pressure check. If it passes, run it and keep checking the oil after the first couple of trips.

 

[s.a.m]

Re: Pressure tested LU

Was there water in the bellows when you removed the drive? If not replace that seal, and re-do the pressure check. If it passes, run it and keep checking the oil after the first couple of trips.

No water in the bellows......What seal are you referring to Don...sorry, i'm still learning....

 

[Don S]

Re: Pressure tested LU

No water in the bellows......What seal are you referring to Don...sorry, i'm still learning....

i can see fine really fine air bubbles coming from the shaft seal after spraying soapy water.....

Fix the seal that has the bubbles. The bubbles indicates the leak.

 

[s.a.m]

Re: Pressure tested LU

The water pump housing is pressurized when the drive shaft is turning so if the pump seals are weak water will be forced through the water pipe and into the lower unit. The pumped water is higher pressure than the oil in the L/U so water will fill the L/U eventually because it will force the oil out through any of the remaining four seals. Does that make sense?

Are you talking about the oil seal on the drive shaft? please tell which one on the pic i provided Captain

 

[s.a.m]

Re: Pressure tested LU

The water pump housing is pressurized when the drive shaft is turning so if the pump seals are weak water will be forced through the water pipe and into the lower unit. The pumped water is higher pressure than the oil in the L/U so water will fill the L/U eventually because it will force the oil out through any of the remaining four seals. Does that make sense?

Captain...Which you referring to the oil seals on the drive shaft? Can you please tell me which one on the pic i provided ....thanks soo much

 

[s.a.m]

Re: Pressure tested LU

sorry for the double post......

 

[GA_Boater]

Re: Pressure tested LU

Captain...Which you referring to the oil seals on the drive shaft? Can you please tell me which one on the pic i provided ....thanks soo much

View attachment 175083

The seals under the water pump on the shaft, where you see the bubbles. .