Leaking 1972 25hp Johnson lower unit oil drain plug

[davidmbv]

Well , I replaced the white washer with OMC part, still drips small amount of oil . I cleaned the threads on the drain hole and bolt. Still leaks. Tried using a o ring and plumbers tape on threads, still leaked. But it was full of oil and not dry when I applied the plumbers tape. The threads on the oil plug and hole seem to thread ok but look at the picture of them, seems damaged .
My plan is to drain the lower unit and then use plumbers tape and washer with everything cleaned up first and try to tighten down the plug and add oil from the top. Has anyone ever ran into a drain hole with damage like this? Is it ok to just add oil from top hole instead of from the bottom? I just picked up this motor and was told the previous owner resealed the lower unit but it was almost dry of oil when I first opened the plug.
Thanks and any advice is welcome. I guess worse case I can pick up a new lower part.

 

[racerone]

To me it appears that a helicoil was installed.----Done poorly ( crooked ?) perhaps.-----Myself I would replace the housing.----Easy for me to say as housings are easy to find here.

 

[davidmbv]

Thanks that makes sense as it does appear crooked when the plug is tightened in. I’ll try plumbers tape and maybe liquid sealant. This was to be my parts motor but the power head and magneto looked so good kind of wanted to revive it.

 

[Crosbyman]

if real stuck you could wash down the openning with carb cleaner... apply a small donut shaped amount of JB Aluminum weld in the openning then ovelapping with a greased nylon seal and insert the greased oil screw .
thigthen down the screw to flatted the JB donut and level the openning under the nylon washer

thighten gently ... just enough to level the openning wait 24 hours and unscrew the bolt and remove the nylon washer .. the bottom shoulld now be flatten and ready to accept a new nylon washer and bolt .
apply plumber's tape if you want and do not overtighten

no harm in trying if plumber'S tape alone does not help

 

[davidmbv]

Thanks I was hesitant to use JB weld because I may permanently lock that plug in but what you suggested makes sense. If the tape doesn’t hold, I’ll give that a try

 

[jitterbug127]

plumbers tape would be my first go to for this.

How would a product like blue monster fair on an outboard motor? I have only ever used it in residential applications. or a marine version?

 

[airshot]

The seat is galled up, that is why nothing seals it. You need to create a new seat/ place that is flat for the seal to go up against. As a toolmaker, I could make a counterbore tool to flaten that surface but if your not skilled at such, the idea of JB weld or other epoxy product could be used to create a flat sealing surface. If you know of a good machinist/ toolmaker, show it to them and they should have acess to a counterbore that would create that flat sealing base you need.

 

[racerone]

I believe the helicoil was installed wrong !!-----A new sealing surface would have to match the way the drain screw goes in at an angle.-----Remove helicoil.----Weld it all up.-----Remachine to factory new, is one option.

 

[saltchuckmatt]

Looks like a heli-coil too...

If you install the lower screw and try to fill it from the top it won't fill. Both screws have to be out to fill.

 

[kbait]

Try a thicker o-ring that will squish against the sides of the drain port when tightened down. Pressure test before filling.. rubber hose and mouth pressure and soapy water will suffice. If it seals, remove plug and fill normally.

 

[davidmbv]

Thanks everyone for all the responses. I tried two different o-rings with plumbers tape but she still drips a drop every few hours or so. I’m leaning towards the JB weld idea to create a flat surface. I’m thinking if I do it carefully and tighten the bolt against the washer, it should in theory crate a surface that matches the angle of the heli-coil…? Using the method described by Crosbyman.
I’m not in dire need of this motor as it’s my third one but kinda got the itch to have another “runner”. If all else fails, I’ll look into taking it off and bringing it to a local machine shop.

 

[oldboat1]

^I've successfully done this a few times using West System epoxy, wrapping the bolt in plastic wrap. When the epoxy begins to set, turn the bolt in and out a little, then let it cure. When cured remove the bolt and check -- should be ready for use. It should work even if the helicoil was inserted a bit off center.

 

[airshot]

You might experiment with coating the threads with a good silicone grease to keep them from sticking in the epoxy. I have had sucess doing this with other epoxy brands.

 

[davidmbv]

You might experiment with coating the threads with a good silicone grease to keep them from sticking in the epoxy. I have had sucess doing this with other epoxy brands.

Thank you, I will give this a shot and see how it goes. I’m tied up with work but hopefully can try the epoxy method soon.

 

[davidmbv]

You might experiment with coating the threads with a good silicone grease to keep them from sticking in the epoxy. I have had sucess doing this with other epoxy brands.

^I've successfully done this a few times using West System epoxy, wrapping the bolt in plastic wrap. When the epoxy begins to set, turn the bolt in and out a little, then let it cure. When cured remove the bolt and check -- should be ready for use. It should work even if the helicoil was inserted a bit off center.

Great thank you