Bf100 overheated

I bought a 1983 Honda bf100 that is in immaculate condition and started easily. I took it out the first day and I couldn't get the fuel line to hold prime so it kept dying but worked fine. The next time out after fixing the fuel line, the motor was peeing just a little bit but I didn't think much of it as it was a new engine to me and didn't know what to expect on the amount. I went out for a few minutes going through different rooms and noticed there was almost no water peeing out now. I shut the engine off and poked a wired through the drain hose tube and into the water channel hole. I couldn't get it started for about 10 mins but when it did it was peeing again. I took off further out in the lake and noticed the flow of water was very inconsistent. After a few more minutes of running it I realized that it probably wasn't working right. I took off and went back in. When I got back near the dock, the engine died and steam was coming out of the cowl. After getting it home, I checked the thermostat and it was completely corroded and not operable. I replaced the thermostat and started it up and it ran and pushed more water out at idle than what I have seen since I bought it and matches what I have seen from some youtube videos of others same engine.
I then checked the oil and realized that the oil is milky and the level was low. There is also oil that is down under the engine as well as some that drained on the ground feom the drain grommet hole in the back left of the engine. I know in cars, milky oil is usually a head gasket but is that the same thing on these? Is there a possibility that I toasted this engine? I am about to tear the head off but wanted to ask what else to look for and watch out for so don't miss something along the way.

Any help would be appreciated as I bought this to hope to be able to go out and enjoy the boat with the family this summer but it has backfired so far.
Thanks!

39 year old outboard in immaculate condition? I would be skeptical…. Sound like you overheated. You might want to inspect/replace the water pump at a minimum, although the milky oil is unfortunate as it could indicate that water is getting in to the crank case, in which case you are just throwing good money after bad. Good luck.

Hi Dave,

I'm afraid I may have some very bad news for you about this. Sadly, Honda built a "GOTCHYA" into these old outboards and the trap gets sprung when the engine is overheated. And it does sound like you overheated it badly.

The problem is that the oil filler (item 15 in the link below) part is made of plastic and can warp enough when the engine overheats that the seal (item 16) is broken. It wasn't great back in the day because to replace the oil filler you have to remove the powerhead from the case.

https://www.boats.net/catalog/honda/outboard/8hp/bf8ak-sa-vin-bacs-1100001-to-bacs-1199999/oil-pump

But, it gets worse. As you can see from the parts page, the part is no longer available. The gasket (seal) is available but, if the oil filler is warped, a new seal won't help. It will continue to leak badly.

But, it gets WORSE! See the round hole on the right side of the seal? That hole is there for the water pump tell-tale bypass! Water flows through that hole and into the bypass hose.

Now, I'm not there, and I could be wrong (I hope am) but I'm guessing that is why you have oil in the bottom of the case and also have water in the oil. These are actually "classic failure" symptoms for one of these outboards after it's been run hot.

I know of no way to straighten the oil filler or to get it to seal after it warps. Hopefully you might figure out a way. I have thought though that someone might be able to make a new one with a 3D printer. Probably would cost alot though.

Sorry for the "dark cloud" but you needed to know this before going forward.

Let us know what you find.

Good luck

Well tha k you guys to the replies. Thank you jgmo for the details in it. It sounds like the worst news I could get for sure, but I'd rather hear the truth than throw money towards it and wasting even more. I will have definitely etly lost a lot of money in this deal, so losing more would hurt. Lol. Bit now I can take it apart, and know what to be looking for and worse case scenario, I sell pats off if it as it seemed to be very healthy til I got a hold of it.

Thanks again and I will report back when I start taking it apart.

Well, I hope that you find a way to keep it going. The base engine is pretty rugged and will survive a good bit of abuse.

But your attitude about selling off the parts, if need be, is a good one. Many of those are no longer available and that motor's parts might just bring you more than you paid for it in the first place.

Good luck.