Outboard motor dripping oil - advice please

[Tam Lin]

I bought a fairly old Mariner 4hp 2 stroke outboard in the winter. It runs nicely but I thought I would give it a bit of a service before using it. I was a bit surprised to find that nothing came out of the gearbox drain hole when I opened it but filled it up and put the motor away. Now there is an oil stain on the floor where it has leaked out. I have looked on Google but all I seem to be able to find are USA sites which say that 9 times out of 10 it is black oily residue from the 2 stoke combustion, which it clearly is not.
It would appear that the seals have gone but I have no idea how to replace them or even where to get them from. Life is hectic at the moment so I would really appreciate some help on this, links to useful websites that explain what to do or advice from the forum.
Thanks.

 

[Lakesailor]

The seal will be on the output shaft behind the prop.

However, getting the seal out of that housing is tricky. There is a bodge using some self tapping screws. My suggestion, if you are not mechanically sympathetic, is to take the motor (or the seal housing which you should be able to remove) to an engineer who may use a press to get it out.

 

[VicS]

I bought a fairly old Mariner 4hp 2 stroke outboard in the winter. It runs nicely but I thought I would give it a bit of a service before using it. I was a bit surprised to find that nothing came out of the gearbox drain hole when I opened it but filled it up and put the motor away. Now there is an oil stain on the floor where it has leaked out. I have looked on Google but all I seem to be able to find are USA sites which say that 9 times out of 10 it is black oily residue from the 2 stoke combustion, which it clearly is not.
It would appear that the seals have gone but I have no idea how to replace them or even where to get them from. Life is hectic at the moment so I would really appreciate some help on this, links to useful websites that explain what to do or advice from the forum.
Thanks.

You dont say how old ... what's the serial number. Once identified we can show you some diagrams and parts lists that may help. An old one could be a rebadged Yamaha.

However if its gear oil leaking then potential places for it to leak are the prop shaft seal(s), the vertical drive shaft seal and the seal (O ring) on the gear shift

If its leaking from behind the prop while standing upright its almost certainly the prop shaft seal as illustrated by LS.


If you don't know when it was last replaced it would be wise to renew the water pump impeller while you have it in the workshop and while doing that you might as well replace the drive shaft seal and the shift shaft seal.

Do the impeller and all the seals and you should be able to forget about the gear case apart from regular oil changes for a few years to come

Warning though old outboards that have not been worked on can be real pigs to get apart ... some mechanics wont work on them!


The Mariner website should find you a dealer in your area . http://www.marineroutboards.co.uk/main.php

Oakley Marine aka Outboards direct are Mariner agents and have given me good service for mailorder parts. http://www.outboards-direct.co.uk/


( BTW its considered good practice not to reuse the seals on the gear case drain and level plugs)

.

 

[Tam Lin]

Thanks both for your answers. I am not at home at the moment so I can't give you the serial number but I did look up the other day and I think it was 1982. I will check it when I get home this evening.

 

[VicS]

Thanks both for your answers. I am not at home at the moment so I can't give you the serial number but I did look up the other day and I think it was 1982. I will check it when I get home this evening.

Pretty sure that will be a Japanese built one..... rebadged Yamaha?

 

[Tam Lin]

Pretty sure that will be a Japanese built one..... rebadged Yamaha?

Hi Vic,
You are correct. It says "made in Japan" on it. The serial number is GEO6 023332 which according to Brunswick Marine is 1982. I have looked closely and the oil does seem to be coming out from behind the propellor.

 

[VicS]

Hi Vic,
You are correct. It says "made in Japan" on it. The serial number is GEO6 023332 which according to Brunswick Marine is 1982. I have looked closely and the oil does seem to be coming out from behind the propellor.

Diagrams and parts lists at http://www.boats.net/parts/search/Merc2/Mariner/4A/6E0-001011 AND UP/parts.html but may also be worth looking up the Yamaha numbers in case of difficulty with Mariner parts.

Take care when removing the seal and bearing housing.

If you decided to do the water pump impeller its necessary to undo the clamp between the two parts of the shift rod by accessing via the rubber plug in the side of the "leg". Note how they are clamped up first.
The driveshaft pulls from the crankshaft and the water tube pulls from the pump.