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Honda BF100S water is oil 1985 motor

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batevv

New member
Hi guys,
I bought a cheap motor with a replaced head gasket and resurfaced head from the previous owner. I've read that the oil filler neck must be replaced and also replaced the crankcase gasket , thermostat and thermostat gaskets with new OEM.
I've cleaned the engine and started it.
For 2-3 minutes of run time the oil got milky and there was about 50-100ml of clean water which exited the drain before the actual milk.
I guess that the engine was heavily overheated as I see small amount of scoring on the two cylinders.
Is it possible that the block has been warped or cracked? The water was a lot.
Any advise how to test it is welcome !Head is currently removed.

Thank you in advance
 
Just thore down the whole engine to bolts and nuts. The block is cracked in the oil return gallery between the water jacket and gallery there is atleast 3 cm crack visible .Another symptom was that in the oil pan the sludge buildup was cleaned from the water.151122799_1141361156274892_7894377634358781903_n.jpg152119836_246701093720880_5180301063481668318_n.jpg
 
All is not lost yet. If you're into it right, you may still be OK. You might be able to find a power head or short block to replace the cracked one at a reasonable price. Or a parts motor...
 
I agree with Alan.

These are some of the most prolific outboards ever produced.

Honda sold...well...a BUNCH!

They were built tough and last long. That's why so many are still in use.

And...the basic parts will interchange over several model years. Often the B100 and B75 models share most of the same components.

If you live anywhere near the ocean or a large body of water then there is always a very decent chance of finding a parts motor for cheap. You just need to hope it wasn't given up on for the same reason yours was.

Good luck to you.
 
I will try to find a block , short block or long block . I think to rebuild completely the engine - so that I know the condition and can count on it.
Are the cylinders, pistons and block ,head from B75 and B100 the same? IF anyone can share info on this It would be great. On my block I can see a stamp -197cc so I guess that it should be an easy task to check.
 
I have never tried to mix and match engine blocks and heads. And, there is a distinction in the parts listing of a change for the 7.5 engine block that shows engine serial number 1006744 as the demarcation point. I've no clue what the change was but it IS interesting that no such change is listed for the cylinder head. That means it will fit either serial number block.

I was told a long time ago that the only difference between the 10 and 7.5 was the camshaft. There was also a rumor going about that a well known Los Angeles Honda shop was offering the "upgrade" and all that they were doing was replacing the cam. I don't know if any of that is 100% true but I have thought about trying it a couple of times. Just another thing I never got around to doing.

Sorry I can't offer you more concise information about this. Stuff like this is why I joined this forum....to learn more about what interested me. But, life happens and can really slow a guy down.

Good luck and I hope that you will share your experiences with the rest of us.
 
The block is totally different. The filler neck is integrated in B75 and removable in B100.Also B75 is 150cc and B100 is 197cc .I found a cheap and good block without the head.
I will receive it soon and re-assemble the engine.I hope that it will finally work properly.
I will let you know re result and post pictures :)
 
Well, that is interesting batevv! Some good sleuthing on your part. I hope your repair goes great and I will definitely be watching for your next post!
 
Your comment about the oil filler not being removable got me to thinking. It's been awhile since I tinkered with these but I do remember the filler necks on the 10 and 7.5 being similar. So I went to boats.net and here's what I found:

The filler necks on the pre 1997 10 and 7.5 models appear to be removable EXCEPT the "LD" version of the 7.5....and that whole engine looks a bit different to me. I have never run across one of those before.

Below: Parts link to the 7.5 LD model showing dipstick and related parts.

https://www.boats.net/catalog/honda...5k2-ld-pre-1997/cylinder-barrel-cylinder-head

Below: Parts link to an earlier model 7.5 showing removable oil filler. All earlier frame numbers I checked showed the same but I only looked up a couple.

https://www.boats.net/catalog/honda...-la-pre-1997/oil-pump-oil-filter-exhaust-pipe

Below: Parts link to pre 97 10hp showing oil filler and related parts. I did note that the part numbers are slightly different.

https://www.boats.net/catalog/honda...bf100-la-pre-1997/oil-pump-oil-filter-muffler
 
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