1997 Gear oil seals

jsers

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Nov 23, 2015
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I have a 1997 40HP Force I'd like to change the gear oil and replace the vent and fill seals. I can't find the blue mercury seals locally, can I use regular orings of the same size?
 

pnwboat

Rear Admiral
Joined
Oct 8, 2007
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4,251
I don't believe that the originals were rubber "O" rings. I'm pretty sure that they are some type fiber or composite material. The rubber "O" rings will get torn up when you tighten up the screws. I've seen quite a few different types of material used. Everything from dead soft copper or aluminum to plastic washers. You may be able to find something at your local hardware or auto parts store. Just take one of the screws with you. They should be able to match something up for you.
 

Frank Acampora

Supreme Mariner
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Jan 19, 2007
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12,004
No, you can not use O-Rings. They will simply crush and squeeze out without sealing.

You do not need to use the stock blue seals. These seals have been standardised for many years and on many different engines. If you can not find them at your Mercury dealer try OMC, Honda, or Yamaha. Color does not matter. And Metric is so close to SAE that the foreign ones will fit. You can even use the old Chrysler white nylon crush seals.

As a bit of added schooling, years ago OMC used a screw with a groove under the head to accept an O-Ring. This prevented it from overtightening the ring while still sealing. They may still be available.
 
Last edited:

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
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17,923
Yamaha uses a different size so make sure it's a good fit.
Can't find them? just tur​n them over.
Make sure they are tight.

Just fixed a 15Yam and the screws were barely finger tight.
Lots of water and almost no oil.
 
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