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Honda BF2AM water in oil

M

mills

Contributing Member
I have a 1997 Honda BF2AM outboard that I picked up. It runs great buttttt is getting water in the oil. I see that it has an "oil flicker" instead of an oil pump, I assume similar to a 4-Stroke lawn motor. Looking at the diagrams it appears that the cylinder head has no water chambers in it and thus the water leak is not because of a bad head gasket. Any guidance here would be appreciated :)
 
Hi mills,
No experience with these but, after looking at the parts diagrams, I agree with you that there's no coolant passages in the cylinder head. Also, I don't believe that the water pump is intended to supply cylinder barrel cooling either as both head and barrel appear to be, as you've said, air cooled....judging from the cast fins in both.
I suspect that the water pump is probably solely intended for exhaust cooling only. I'm not sure how water from the pump would enter the crankcase through exhaust but, I suppose, anything is possible.

For water intrusion into the oil, on an outboard of this design and age, I might be suspicious of the oil and water seals that are "stacked" against one another at the bottom of the oil pan. See items 11 and 12 in the link below.


If both those seals were failed, water could "push" up through both as the outboard moved through the water. Especially if it were mounted very low on the stern.
Although, if that were the case, I would also suspect an oil leak at that location when the outboard was stationary. So, just guessing about the possibilities here.

The good news is that both seals are still available. Not true for MANY of the repair parts for this one any longer.

You might also want to investigate the water tube to engine connection in case my theory is all wet and water is indeed entering via the exhaust system. Items 4,5,6,and 7 in the link below. None of those seals appear to be available but could possibly be fabricated if there's enough left of the old to copy.


Another possibility that comes to mind is that water might find it's way to the oil via the crankcase breather system. Items 6,7,8 and 9 in link below.
The valve and gasket are still available too!


Out of "ideas" but I will keep thinking on it.

Meantime, here's where you can purchase the shop manual if interested.
Be sure to match up your vin number before ordering as there are more than one offerings.

Honda Marine | Shop Manuals Publications | Honda Power Products Support Publications

publications.powerequipment.honda.com publications.powerequipment.honda.com

Good luck.
 
Jgmo,
Thanks for your input. You gave me a lot to think about!! I might add that the water was getting into the oil when I had the motor on a stand and the lower unit in a bucket of water. I will check out your links closely. Thanks again for your time.
 
Well, that info pretty much shoots down my lower seals idea.

So, I would focus on how the water from the water tube is directed into the engine.

I wouldn't think that there would be an oil cooler on this outboard but... who knows?

Here's where having the shop manual would probably really help.

Hope you fix it!
 
jgmo,
Ran a little test. Not sure what it means butttttttt dropped the lower unit and hooked up a hose to the water inlet tube. Introduced compressed air into the water tube. No air came out of the oil fill/drain?????? How is it that water can get in the oil but air can't????
 
Well mills,
You got me there bud....

While that sounds like a good (and very creative I must say) test, I have to ask where DID you find air escaping? The exhaust? Did you try slowly rotating the engine while the air was hooked up?

It could be that the air is simply taking the proverbial "path of least resistance"....I don't know.

Let's go back and revisit my stacked seals (items 11 and 12 in the link below) theory.

I believe that it's possible that, as the crankshaft turns the vertical shaft, (item 12 in the link below) water flooding the extension case could be dynamically "pumped" upward.and through those seals if the seal's or the seal wiping surfaces on the crankshaft are compromised in some manner.

"Shaft pumping" of fluids is a real "thing" although I couldn't find an adequate example to give you.


Again, it's just another theory but it could have merit in this case. That would explain no oil loss while the engine sits in your tank but the shaft picking up water and "pushing" it upwards when running could produce enough force to work it past the seals.

Wish I had a better answer but, hopefully, someone else here can step in and teach us both something.

In the meantime, since it sounds as if you've already done much of the tear down needed to get to those seals, I would urge you to replace them since they're both still available. And, maybe not for much longer too!

Also, I would closely scrutinize the shaft surfaces those seals ride on for this vintage outboard. If there's a problem there, you may be able to utilize an appropriately sized "Seal Saver" sleeve to get another 30 years out of her. I also see that the crankshaft IS still available for $150 along with standard AND 0.25mm oversize piston rings too!

Good luck and please keep us updated on what you find. This is a very puzzling case that I hope that you will solve.
 
Yes, the air is just exiting through the exhaust. Unfortunately, the water seal (part # 91203-ZV0-003) is not available, but the oil seal is. What I am going to do is to put some gasket/seal expander in the oil and run the motor for a while. It may expand the oil seal just enough to keep the water out. I have seen that stuff do wonders!! I am a little reluctant to remove the 6 bolts that hold the oil pan to the engine casing and separate the 2 casings. I have done similar things in the past that resulted in a destroyed motor. If the gasket expander snake oil does not work then I will go and take the engine apart, although I don't know what that will tell me?? Maybe there is a crack or something??
 
Yes, I see your point. I don't know why I thought the water seal was available since it clearly is not. Getting old in my old age.

Problem is though, I'm guess that water seal is likely to be the reason for the leak.

Here's why I think that:
The oil seal is likely a single lip oil "retention" seal intended to only keep unpressurized oil in the oil pan contained. It probably only has a "dust skirt' to exclude only atmospheric pressure to keep anything out.

With the water seal failed and the shaft creating a bit of flow, the oil seal dust cover is likely being overwhelmed and allowing the water to enter.

If that' is what is happening, the "seal softener" probably won't help because the seal IS working as intended because oil isn't escaping the sump at present.

But, I'm guessing just as much...or more...than you are.

Correct me if I'm wrong but I wonder if, since it seems you're right there, you might be able to try a "patch" job on that water seal?

From the parts illustration that seal looks like nothing more than a big rubberized cup that fits around the oil seal. If that's the case, I might try using some Permatex RIGHT STUFF gasket maker and work it into and coat the seal. I would then slowly rotate the engine while the sealer is still soft so that it doesn't adhere to the shaft.
Rotation just after applying and then every couple of minutes after that until it begins to cure would help ensure that there would be no adhesion to the shaft.

Another thought, in case you do find that you need to replace the oil seal is to maybe "redesign" the water seal?

I wonder if replacing that seal with an additional oil seal turned around to exclude pressure might work? The problem would be anchoring it so that it didn't turn with the shaft.

And then there's leather.

Leather was used for decades as an effective seal material and a couple of wraps of leather cordage inside the old water seal housing, held in place with some gasket maker, might just work.

I'll be very interested to see what solutions you come up with and how they work.

Definitely here in your rooting section and cheering for a win!

Good luck.
 
Jgmo,
The sealer did nothing. There is now a a large puddle of oil below the motor :( Just because they say the water seal is not available does not mean that no one has one. I'll start calling Honda outboard dealers to see if I can find one....................after I get the engine apart. Thanks for your input..........
 
That's bad news.
When you say sealer did nothing, could you explain?
Did you try using the gasket maker or did you use the oil additive or both?

You could be right about getting lucky and finding that seal on a dusty shelf someplace. Ebay might be a good place to search also.

I looked it up on the Japanese parts site Yumbo.com too but no joy...
..."discontinued" there too.

Sorry.
 
Excellent suggestion William01! Thank you!

Yes! Taking that depiction with dimensions to a specialty bearing supply house is something I should have already thought of since I would do that often when I had my truck shop.

If there's something left.of the old seal, they will want to see it in person too so they can use their calipers on it.

It being so unusual in shape it's still a long shot but you never know.

They might also have some good ideas for an alternative "type" that might work there.

Make sure to take the shaft diameter to them as well.
 
Well, thanks again for all your input. I removed the extension case and, just like Jgmo said the only thing the water does is cool the exhaust. No water goes up into the engine block. Right there is the water seal. It prevents water from touching the steel crankshaft. The seal is around the SS driveshaft. It looks good, but must be bad since it is pushing water into the crankshaft seal and then into the engine. I obviously need a new water seal and oil seal. There are a bunch of numbers on the water seal that I may be able to research. My main question now is can I replace both seals without having to remove the oil pan casing???? Stay tunned :)
 
Well, I lucked out and found the seal on Replacementparts.com. I was able to remove the old seals easily without halving to take off the oil pan. Now I must sand the rust off the crank so the oil seal will seal. Very poor design by Honda. I think the water pump is producing too much pressure which causes the water seal to leak which then causes the crank to rust which then causes the oil seal to leak :(
Thanks for all your help ......................
 
Sheesh man! That's incredibly lucky! And I would have NEVER thought to look at Replacementparts
com. GREAT IDEA!

The water pump wouldn't cause that I don't believe. It doesn't pump water to that seal. I just think that use and time caused the seal to fail.

I would be very careful sanding that shaft and I suggest finishing up by using
crocus cloth to get a final finish.

Hope it works out well.

Let us know and good luck.
 
The water seal is the only thing that prevents pumped water from touching the crankshaft. If it fails water hits the steel crankshaft and it rusts, causing the oil seal to fail. I can send you pics if you like.
 
Well then, I clearly am not understanding what you're seeing. I was under the impression that the waterpump sent water up through the water tube to the exhaust pipe and nowhere else. Apparently I don't have that right.
 
Attached are 2 pics showing where the water goes. It enters where I have colored white and then fills that whole compartment with cooling water. This includes the bottom of the oil pan where the driveshaft goes into the crankshaft. Again, the only thing preventing the water from coming in contact with the steel crankshaft is the water seal that seals the driveshaft. I also think that the water helps to cool the oil because it cools the bottom of the oil pan. Hope the pics explain this. :)
 

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Thanks for the pics and explanation mills. You're probably right about the oil cooling aspect of it too.
I learned something new again today!

Still AMAZED that you found that seal!

Hope the FIX goes well.
 
I just used Google search and put in the Honda seal number and a number of sites popped up including Replacementparts.com
They were the only one that had the seals in stock. :)
 
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