Johnson foot question

[Rbsgfd578]

I have a 1984 Johnson 90hp and today I decided to check my foot oil, yup theres the bad news took the drain screw and out came water and then milky oil.I just had the foot totally resealed last year and today didnt notice any oil leaking around the prop.So what I am wondering is there supposed to be an "O" ring or something on the drain and the vent screws on the foot?If so could this be where my water came from over time instead of a bad prop seal? When I looked in the holes where the drain and the vent screw came from there is a blue look like seat made into the foot, I tried to pry them out gently to see if the were "O" rings that maybee had went bad but they wouldnt budge..
Thank all your help is greatly appriciated.

 

[HighTrim]

Re: Johnson foot question

The gaskets on the drain and vent screw are the number 1 spot for water intrusion, and should be changed each and every time you service the lower unit. I would replace them, along with fresh synthetic lu oil, then check again after an outing. The water will sit at the bottom of the oil, so you will just need to empty a bit to check for water intrusion.

 

[samo_ott]

Re: Johnson foot question

Is it a seat behind the screws or a jammed up washer? The new washers are translucent and should always be used... they're real cheap. Get a bunch of them when you go to the OMC dealer...

 

[Rbsgfd578]

Re: Johnson foot question

1 more quick question.I found where the oil was leaking down from and it was the top vent screw just abouve the anit cavitation plate.What I think happened is we had a couple of nights of below freezing temps here and most likely the water in the foot froze and pushed the oil out of the top vent screw area.If this is what happend could I expect more damage from the ice once I put new oil in it and replace the "O" rings?
Just on a side note I always store the motor in the trimmed down position so this would be why the oil was able to be push back up the the vent screw.

 

[samo_ott]

Re: Johnson foot question

It's possible that happened. I've had a skeg freeze and crack due to water in it. And as water expands 9% when freezing (or is it 11%) it could push out the top. Change the oil and put new gaskets on the screws and see how it goes I would say.

 

[HighTrim]

Re: Johnson foot question

Correct Steve. When water freezes, a 9% volumetric expansion occurs during the transition into ice. This can exert a pressure on the adjacent material (ie the lower unit casing). If there is water in small openings in the lower unit such as pores or cracks that cannot allow for a 9% volume expansion, breakage of the adjacent material will occur. The volumetric expansion of water/ice can only be prevented by pressures of 207 MPa, which is the pressure melting point of ice. Unfortunately most lu's cannot stand that kind of pressure.

If the pressure of ice exceeds the tensile strength of the adjacent material (in our case the lower unit casing), the lower unit will crack.

Useless information really, but a little FYI.

 

[Rbsgfd578]

Re: Johnson foot question

Thank yall very much for the info.Since I am assuming here that I didnt see any oil or water leaking from the casing of the lower unit except around the screw that hopefully I will be ok..Heading tommorow to get the gaskets for the screws tommorow at a whoping $0.55 a piece, its bad that you can almost mess up your lower unit bad for being negligent and not spending a whole $1.10....

 

[HighTrim]

Re: Johnson foot question

Sad but true. I always grab a handful of them when Im at the dealer. A buck seems like a good bargain doesnt it compared to the alternative. May also want to run some synthetic lu oil until you determine you solved the problem. Good luck.

Chris