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Honda 1981 BF75 7.5 hp coupling - lower crank seal

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alumarine

Regular Contributor
Thanks to hondadude I got my water pump parts ordered and hockeyguy helped me remove the extension case.

I removed the extension case to replace the upper water tube seal.

I noticed that where the upper part of the vertical shaft goes into the motor it's slightly oily.
I'm wondering if I should replace that seal.

Is it part no. 32 Coupling Seal in the attached diagram?
If so, is it as simple as removing part no. 3 Plate and also replacing part no. 4 Band?

I'm not too worried if it just leaks a slight amount of oil.
I don't want to open a can of worms trying to fix it.
It's a backup motor for my bow rider in case the main motor dies.
I only run it for about 1 or 2 hours a year just to see if it runs.

thanks

http://www.boats.net/parts/search/Honda/Outboard Engine/0/BF75B LA/OIL CASE ENGINE COVER/parts.html
 
Well, it's not quite that simple. But not super complicated either.
Oil would be coming from the crankshaft oil seal. That seal is listed on the parts page titled "crankshaft piston".
The plate and band you referred to is for engine exhaust.
I hope this helps.
Good luck.
 
That does help a lot.
I'm going to leave it alone then.

I'm now wondering if the oily film I felt wasn't from the exhaust.
It does blow a puff of blue smoke the first time it's started if it's been stored on it's side.

Thanks a ton.
I'll just replace the water tube seal up there and put the extension back on.
 
Yeah, I thought the same thing. The oil could be coming from the exhaust. But you should know that pulling the power head on these is comparatively easy and anyone with moderate mechanical abilities shouldn't be intimidated by it. Also, if you did decide to "go in", having the power head off affords the opportunity to replace the exhaust gasket that fails a lot on these as well as gives access to the permanent oil filter that is typically pretty gunked up by now. There are a couple of other items that are "must do" while you're in there that would probably help significantly extend the life of the outboard if you choose to do them.

Also, you will want to examine carefully the area that the water tube seats in on the block. I find that there can be considerable oxidation "erosion" in that area and, if bad enough, won't allow a new seal to fit correctly. I have removed the "rotten" metal and rebuilt that seal "boss" using industrial epoxy with good success.

Good luck.
 
Thanks for the additional info.
If it wasn't July already I'd go in deeper.
I just got my boat ready to go and this is my last hold up.
I think this year it will just be the impeller and seals and over the winter I can do the rest.

I did notice some oxidation on that upper seal cavity so I'll take a closer look.

Thanks again.
 
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