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Strange old Bf8A oil puking

Hey all, I was recently gifted a sailboat with a long neglected 97 Honda BF8A outboard. I took the motor home, cleaned the carb, replaced the coil and it ran really well. Took it back to the boat and got nothing from the telltale. Pulled the lower unit and while the pump impeller was distorted it wasn't broken, although the pump intake had an incredible amount of corrosion and junk in it.

Cleaned it all up, replaced the impeller and fired it up again. Still no water out the telltale. Assuming junk in the cooling lines I sucked on the telltale hose and sure enough got a mouthful of sediment and it started flowing warm water. Popped the telltale back into it's place and it quickly stopped flowing again.
Suddenly the cowl bowl started filling up with oil and we shut down the motor. Called it a day.

Hauled motor back to my shop, started it again, no oil leakage and although we were running it temporarily dry I could feel the pump pulsing air out the telltale.

Took off the intake manifold and cleaned a pile of sediment out of the coolant galleries and thermostat, removed the lower gearbox and shot compressed air through the now-open cooling system. I'm going to replace thermostat tomorrow and I think I've got all the junk out of the cooling system, but I'm really puzzled by that sudden appearance of all that oil. I visually checked the pressure switch, dipstick plate and hoses to the breather, and eyeballed the oil pump and couldn't see any leaks or signs of leaks the few moments I ran it on the bench.

Bear in mind this was a LOT of oil - most of what was in the sump quickly got pumped out. And now doesn't seem to be doing it. I was thinking head gasket, but there's no water getting into the oil sump. I can't visually see signs of oil leakage anywhere. I'm scratching my head to see the relationship between plugged cooling system and sudden appearance of oil.

FYI it seems that only the intake manifold coolant circuit was plugged and cooling water was still making it's way around the cylinders. This engine probably sat for at least 2-3 years, with very intermittent use before that. Salt water.

Any suggestions regarding the oil leak?
 
Well, my first guess about the oil leak is that, while it sat, a critter could have built a nest in or about the crankcase breather. It could have actually been in one of the hoses that you checked AFTER you ran it awhile and blew out the obstruction. Hot oil and vapor would likely have reduced a spider web or similar down to something you may have easily missed during the mop up.
The amount of oil loss from the sump could have been a siphoning effect when the obstruction suddenly cleared. I'm not sure about that, just a guess.

Other than that, a dried out crank seal leaking badly then sealing up after getting wet and hot??? Oil pump regulator valve stuck??
Another set of guesses of course.

Just need to run it some more and see if it does it again.


I don't understand your thinking though about running the water pump dry. That usually destroys the pump's efficiency immediately. It's why we grease 'em up when they're new.

If you intend to rely on this auxiliary I strongly recommend replacing the pump.

But that's just me.

Good luck.
 
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I don't know much about these little guys, but I do know that if the motor's crankcase can't vent to the atmosphere properly, it's going to build pressure and start blowing oil out wherever it can. Hope that helps!
 
Just goes to show that each job can be completely unique, and ordinary troubleshooting can't be replaced by tearing things apart. I ran it in a garbage can filled with water and watched the oil sitting in the bottom of the cowl. Looking around the engine, there were no drips or leaks, but that level slowly rose again. I guess the other day we were so focused on the lack of cooling water didn't notice the oil rising until it topped the cowl and started leaking overboard.

Assuming it must be a leaking crank seal, I pulled the powerhead. Turns out it couldn't have been that because it's at the other end of the engine, where there are separate sumps, and those didn't have oil in them, only the most rearward one by the exhaust.

What it did turn out to be was all the filth and corruption sitting years in the bottom of the cowl sump slowly dissolved away the wall of the oil sump. It ate a small hole through it, and that oil I saw sitting in the bottom of the cowl that I though was from years of people being sloppy filling it with oil, was actually half of the oil sump volume. It was continuous with the oil sump.
By pulling the power head I was able to discover that hole. I was also able to get the breather apart and find that the reed valve was (slightly) stuck closed. It popped open with a little pressure. But more importantly, the breather hose that exits the cowl was plugged with more filth and corruption.
So my theory is that as crankcase pressure increased, the pressure on the oil pushed it out into the cowl sump, eventually pushing it right over. Amazing!
For now I've plugged the hole with a big wad of mouldable metal filled epoxy. I'll keep an eye on the cowl sump to see if I ever see oil in there. If the engine proves to be decent in the future I'll pay to get it welded but I don't want to sink any more $$ on this thing until I can see that it's worth it. It isn't a critical problem with oil going into the cowl sump, as long as it's not under pressure. We'll see.
 
At least now, you know what to expect. Good job, and good luck!

If you decide you like the little guy, maybe pick up a parts motor and swap the blocks/short blocks....
 
Today was a battle with it. Found corrosion around Intake that I sealed off with mouldable epoxy, poured some epoxy into the oil sump as extra sealant for the earlier putty repair. It completely covers the hole so impossible to leak now. Found two broken off motor mounts, fixed those by drilling out and running a bolt through. Put everything together, no oil leaks but still only spitting water out telltale. I KNOW the water passages are clear.

About ready to give up on the POS, but I'm stubborn. Pulled the gear unit, took everything apart down there, pump looks fine. Look up into the leg and see the seal on the water pipe where it goes into the pump housing - it's got a protruding "tang" where the first time I guess I shoved the gear unit on the pump housing caught the seal and tore it, just pushed it up instead of it going into the housing. I pulled it off the pipe, carefully inserted it into the pump housing, shoved everything back together, started it, and now making water like a racehorse. I wasn't aware of the seal, but it looks like it's supposed to be on the pump housing when inserting the lower unit, not left on the pipe.

So far this "free" motor has needed a new coil, repair to the head, repair to the oil sump, new intake gasket, new pump impeller, pump gaskets, 2 kinds of epoxy, gasket maker, thermostat, 2 litres of oil and like 20 hours of my life. I think I'm up to about $250. The good news is I know this outboard inside and out and know how to tear it down to the block, not a bad thing when you're a sailor and need to be able to make emergency repairs on the go. But I'm going to leave it running in a garbage pail a good long while before I trust it on the ocean.
 
Watch the water temp in the garbage pail. It may heat up quicker than you think! Good job on sticking with it, troubleshooting until it's right. That's pretty much how I learned the 40's & 50's. Only they're STILL teaching me new ways to screw up on occasion!
 
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I get why they stopped making 2 strokes but man, they were so simple and lasted forever. You could pull that 1940 seagull outta grandpa's garage, give it fuel, a couple of pulls with the starter cord and 9 times out of ten it would start right up without problems.
 
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