Mercruiser Alpha 1 Gen 1 (1.47ratio) Milky Gear Oil

JJBoatr

Petty Officer 2nd Class
Joined
May 3, 2011
Messages
144
Hey all,
I changed the impellar+upper housing a week ago and after inspection and recommendation from a marine mechanic I re-used the lower housing but replaced the big o-ring on the bottom. Now after running it for only about 25mins on the boots my gear oil is milky again:mad:. I just bought the boat last year and when I drained the lower unit to change the impellar the gear oil was milky. Right now I am thinking either the lower impellar housing shaft seals are shot or the prop shaft seal is bad. Leaning more towards the housing seals at this point. Alternatively; Could there have been enough milky lube stuck to gears and such that it could've turned my new lube milky as well? Long shot but worth asking. I have lost faith in my mechanic because he installed my upper vertical driveshaft seal wrong and if I had not caught it, I would've cooked my drive. I read through how to pressure test the LU but I don't have the guages and such at this moment. I am going out to pull the impellar housing right now. I would just like to know if I'm on the right track. All inputs are greatly appreciated.
 

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: Mercruiser Alpha 1 Gen 1 (1.47ratio) Milky Gear Oil

for sure put the parts back in right. then the pressure test should lead you in the right direction as to weather ya got a leak or not..... i always pressure test mine after i open it up.. makes me feel good to see the gauge stay at 14psi for a long time.. if it don't, i'm on the hunt for a leak..
 

JJBoatr

Petty Officer 2nd Class
Joined
May 3, 2011
Messages
144
Re: Mercruiser Alpha 1 Gen 1 (1.47ratio) Milky Gear Oil

What about the possibilty of bad lube clinging to gears+casing and turning by fresh lube mustardish yellow? I pulled the lower impellar housing and he seals look good. I'm thinking of changing it for peace of mind. Is this a waste of time + $? Or a good move. I pretty much ruled out the prop shaft seal at this particular moment because it isn't even getting wet while it's running on the boots.
 

JJBoatr

Petty Officer 2nd Class
Joined
May 3, 2011
Messages
144
Re: Mercruiser Alpha 1 Gen 1 (1.47ratio) Milky Gear Oil

Found the problem...I pressure tested the lower gearbox using an air gun with a soft rubber nozzle and the compressor regulated at 15psi. The culprit appears to be the shifter shaft seal. It was the only thing making noise with the case pressurized. Every thing else seems to be in good repair. How is this seal to change? Special tools? Or can a DIYer handle it. Thanks for the help Ziggy:)
 
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