1967 Johnson 9.5hp small hole in the bottom of the fin directly above prop

I just purchased my first boat (total noob)... a 14' Jon boat with a 1967 Johnson 9.5hp outboard which looks restored, it's very clean and appears to have grease in all the right spots. The engine starts on first pull (even in gear... to my dismay). After taking it out on a lake for a day I noticed a slight oil leak in lower unit.

Upon careful inspection I see there is a small hole (approx 3/32") in the bottom of the fin directly above the prop. It looks like a factory hole. I changed the lower unit oil and found water in the oil. The oil and water were leaking out of the hole but only a small amount... it's not a mass leak. Is that hole suppose to be there?

I changed the oil and tried another trip to the lake. Again engine ran great but when I got home I see the same result with water/oil and it?s leaking out of this hole just the same as before. I'm worried that the water is getting into the L/U Oil through the hole. I bought a Service manual and none of the graphics show the bottom of the fin at all and none of the breakout drawings ever reference the hole.

Also? my Engine Model Number is 9722M, however, any reference I can find is always 9722B? Does anybody know why there are no M references anywhere? Does this matter? Is the M for Mechanical Shift? The engine has forward, neutral and reverse via flipping a lever up and down. Thanks in advance for any help you can provide.

Re: 1967 Johnson 9.5hp small hole in the bottom of the fin directly above prop

The hole is supposed to be there. It is a drain hole. What does it drain?? Well it drains water and other crud that otherwise would lay there in a low cavity in the casting. What is the other crud?? Remember that oil you put in the gas? Every drop of that oil goes through the engine and some is burned (smoke) and the rest goes out the exhaust. And that is what you are seeing drain out that hole.

I would have to research the M and B. It indicates some mid-year engineering change.

EDIT: I can't find an "M" either. But that is what the suffixes mean---mid year engineering changes. Since I can't find it, I don't know what the change was. But it probably was minor.

Re: 1967 Johnson 9.5hp small hole in the bottom of the fin directly above prop

Thanks much for the reply. I'm glad to hear that the hole is in fact intended and not the result of a small rock or something like that. So here's the thing though... The Oil I drained out of the L/U the first definitely had water in it (milky looking). That Oil was brownish in color, I used a magnet to check for shavings and found none.

The new oil I put in is Blue in color and the oil/water mix that is coming out of the small hole now is blue(ish). Is it possible that the gearbox in the lower unit vents (from pressure) into the cavity through which this small hole drains stuff?

I'll actually have a chance to drain the L/U Oil again this weekend; I haven't had a chance since the last trip to lake. Due to the meticulous condition of the rest of the engine I'm guessing the L/U also got treatment when it was restored... so I'm not to inclined to believe it's time for new seals already. Although I will certainly put them in if there is water in the L/U Oil when I drain it this time.

Re: 1967 Johnson 9.5hp small hole in the bottom of the fin directly above prop

Um...isn't the oil you put in the gas also blue?

Anyhow, it would take a gearcase leak of extreme proportions to notice it leaking out that hole, although it is possible. It would be the shift rod seal, if it is.

Not saying you don't have a gearcase leak, since you are telling me that water is getting in.

I found the "M" The drive shaft seal and prop shaft seals were changed. "B" models use seal number 313282, and "M" models use seal number 303345. Both shafts use the same seal number.

Re: 1967 Johnson 9.5hp small hole in the bottom of the fin directly above prop

I still haven't had a chance to drain the L/U Oil so I have no status on that yet. The oil I put in the gas is actually red in color. I wanted to thank you for taking the time to find out what the "M" in my engines model number was for, I really appreciate that very much. As soon as I get a chance to have this taken care of I'll post my results just in case anybosy else ever has a similar experience. Thanks again for all you help.

Re: 1967 Johnson 9.5hp small hole in the bottom of the fin directly above prop

There's a chance you've got a leak in the driveshaft seal. Oil will leak out past the bad seal, and then exit through the drain hole (as you've witnessed). I'm not intimately familiar with your engine, but I'm quite sure the lower units are similar to the ones I've worked on. The driveshaft seal is going to be underneath the water pump.

Re: 1967 Johnson 9.5hp small hole in the bottom of the fin directly above prop

If you find any water in the L/U oil next time you drain it, take it in and have it pressure tested. That will take all the guess work out of it.

Re: 1967 Johnson 9.5hp small hole in the bottom of the fin directly above prop

Drive shaft seal is in the water pump intake area. Oil leak there will enter the cooling water and be pumped through the engine. OR run out the water inlet screen. That hole is in the exhaust area. Both cooling water and exhaust discharge into that area. But it would take a really major gearcase leak to not be diluted beyond recognition at that point.