leaking gear oil from lower unit of 1984 mercruiser alpha

[jonespj]

Hello, I'm a first time user of this site. I did send a similar question a week ago and must not have sent it right ...no responses. I pulled off the lower unit because of oil seaping from the small weep hole at the bottom. I pressurized the lower and then the upper unit and with soapy water everywhere I just could not locate a leak so I put a new shift shaft seal in anyway and reassembled. Its still leaking. My question, how much pressure should be used. I went to about 5 psi(didn't want to blow out some seal and make things worse). Also last fall I put in new impeller kit (thats when it started leaking, it had not leaked at all before I pulled it down). It overheated once last season. The impeller kit came with some new seals which I used but that o ring that fits on the top of drive shaft wasn't included so I reused the same one. Does that o ring play any part in keeping the oil in where its supposed to be? Thanks for any help and suggestions, Paul

 

[achris]

Re: leaking gear oil from lower unit of 1984 mercruiser alpha

Hello, I'm a first time user of this site. I did send a similar question a week ago and must not have sent it right ...no responses. I pulled off the lower unit because of oil seaping from the small weep hole at the bottom. I pressurized the lower and then the upper unit and with soapy water everywhere I just could not locate a leak so I put a new shift shaft seal in anyway and reassembled. Its still leaking.

There's a surprise!

My question, how much pressure should be used. I went to about 5 psi(didn't want to blow out some seal and make things worse).

No, you need about 12-15psi. And move the shafts around whiel the pressure's on... Some only leak when in certain positions.

Also last fall I put in new impeller kit (thats when it started leaking, it had not leaked at all before I pulled it down). It overheated once last season. The impeller kit came with some new seals which I used but that o ring that fits on the top of drive shaft wasn't included so I reused the same one. Does that o ring play any part in keeping the oil in where its supposed to be? Thanks for any help and suggestions, Paul

That 'O' ring doesn't do anything with respect to keeping oil in... Later drive shafts don't even have the groove. My experience is that putting that 'O' ring on can hold the lower seal open and allow water into the splines... Shortly thereafter the splines rust away....

BTW... Welcome to iBoats Paul...

Chris.....

 

[jonespj]

Re: leaking gear oil from lower unit of 1984 mercruiser alpha

Hey, I really appreciate your fast reply. I won't be able to work on it till next week-end but I'll put the pressure to it next time . Thanks again, Paul

 

[achris]

Re: leaking gear oil from lower unit of 1984 mercruiser alpha

Hey, I really appreciate your fast reply. I won't be able to work on it till next week-end but I'll put the pressure to it next time . Thanks again, Paul

You did empty the drive of oil before the pressure test, yes?

 

[jonespj]

Re: leaking gear oil from lower unit of 1984 mercruiser alpha

Yes I did drain it first.For a follow up when I test the upper unit ( with lower removed) is there a easy way to check for leaks or just spray soapy water inside and out and keep looking

 

[achris]

Re: leaking gear oil from lower unit of 1984 mercruiser alpha

I usually use my ears first, see if I can hear where it's leaking.... Once you determine which half the leak is in, you can start looking in the right area.

Leaking top box ('Drive-shaft housing'). 4 possibles..
1. front main seal (will leak oil into the bellows)
2. front 'O' ring (will also leak oil into the bellows)
3. top cover 'O' ring (leaks oil to the outside world)
4. leaking upper drive-shaft seals (will leak to the top of the lower box)

Leaking lower box ('Gear housing'). 5 possiblies
1. shift shaft seal
2. shift shaft seal bushing 'O' ring
3. prop shaft seals
4. bearing carrier 'O' ring
5. lower drive shaft seals (under the water pump)

HTH....

 

[jonespj]

Re: leaking gear oil from lower unit of 1984 mercruiser alpha

I've copied those symptoms/causes down for future reference. Thanks for your help!

Paul