Saving Old Seagulls

I have got an old Mariner outboard which I am messing about with. Its a 1984 two horse power job. It runs nicely but I wanted to give it a bit of an overhaul. I dont know if anyone is familiar with one of these motors but I am missing an oil seal in the water/impeller housing.

In the image below it is part number 17 (this shows 2 seals back to back but my version is a bit older and only has 1 seal). This is a the housing where the seal sits. There is another seal just below the impeller housing, that seals the drive shaft into the gear box, so I am not sure how much the missing seal actually does apart from keeping dirt and debris out of the impeller housing. I haven't found (yet) a supplier for the original part, so I looked at a few sites that sell seals off the shelf, to see if I can find one that will do the job. To be honest I know very little about seals, how they are fitted, the different types etc etc. I do know that the old seal was rubber with a metal inner and had 2 garter springs inside. The drive shaft that it needs to sit on measures 10.67mm dia at this point and the housing it sits in is 20mm outside diameter and the recess 7-8mm deep.

Do I need to buy a seal that is slightly larger than the drive shaft considering it is rotating within it? If so how much clearance should I allow. Would something like this do the job?
http://simplybearings.co.uk/shop/p25660 ... _info.html

I notice that this one only has one garter spring, is this critical? If so is it feasible to buy two and install back to back?

Any help really appreciated

Have you tried:
www.boats.net

Looks like they have it
http://www.boats.net/parts/search/Yamah ... parts.html

Thanks Michael. It does look like they stock the part, the postage costs from there are a bit steep though at 15 dollars. I was hoping for a cheap fix. The oil seals from the link I showed averaged about £3 each which I why I was hoping I may be able to use one of those.

I will ring around and see if someone can source one from the UK.

Having done a bit more looking I think this is the right model. http://www.boats.net/parts/search/Merc2 ... parts.html. Part number 16

I did get a quote, but it was over £20 for a Mariner part, apparently the same part from Yamaha is a bit cheaper, but still expensive. Also I had measured the drive shaft wrong, there are sections that are turned down to smaller diameter, but the section the seal sits on is 11mm. I spoke to a UK oil seal supplier and gave them the spec and dimensions (11mmx20mmx7mm thick) and they are sending another one for £5. I will see how the budget fix goes!

Yes the OEM are very expensive for parts, but i always buy bearings and seals from a bearing supplier. Much cheaper, also loads on ebay.