Cleaning Out Hydro-Electric Gearbox

[jay_merrill]

One of the members reported a problem with his 1969 Johnson 50hp motor. It seems that the motor had been sitting for about 38 years with Type C gear lube in it. When he tried to run the motor, it would not shift fully into forward gear.

I don't know that the cause of this problem has been determined (the thread died), but I wondered if it was because of thickened gear oil gumming up the ball valves and screens in the pump. I also wondered if thickened lube would cause the pump to be unable to produce the appropriate amount of oil pressure in the gearbox to operate properly.

So, here's my question ... if this is indeed the problem, is there a way to flush a hydro-electric gear box by replacing the lube and mixing some sort of solvent with it? Can the gearbox be operated with such a mixture for some short period of time to remove deposits? I suppose if this is a recommended procedure, some method of flushing the mixture out later on would be required.

What say you, experts? Frankly, I'm just curious on behalf of this person and myself, as I now own two 1972 Johnson 65hp engines - one that is currently a great "runner." and one that I picked up recently for $150, but appears to to have serious potential.

 

[tashasdaddy]

Re: Cleaning Out Hydro-Electric Gearbox

i have used diesel fuel, to flush all kinds of things. especially milkshake out of lowers. i don't believe it would hurt, for a short flushing.

 

[F_R]

Re: Cleaning Out Hydro-Electric Gearbox

No oil pressure is required for forward gear. It would be in forward even if the gearcase had no oil at all in it.

Ground up metal powder in the oil will keep the dog/piston from sliding in the oil pump bore and possibly prevent sliding into forward. If that is the case, flushing won't help. It will be imbedded in the aluminum by then. Good reason for periodic changing of the gear oil though.

 

[jay_merrill]

Re: Cleaning Out Hydro-Electric Gearbox

Thanks TD and FR. The fellow that I mentioned has sort of a strange situation because the motor was purchased, run for one season, winterized and then not used for 28 years. Its also curious because the motor does lock fully into forward when not running.

 

[F_R]

Re: Cleaning Out Hydro-Electric Gearbox

How do you know it is truly "locked fully into forward"? Unless you are as strong as 50 horses, you can't apply that much torque to it by hand or foot.

 

[jay_merrill]

Re: Cleaning Out Hydro-Electric Gearbox

Just an update - I had a conversation yesterday with one of the older mechanics at my local OMC/BRP dealer. We got to talking about various aspects of the hydro-electric shift, which made me think about this thread.

He says that he has used Dextron II automatic transmission fluid to clean out hydro-elecric gearboxes. He also said that these gearboxes operate just fine with the Dextron as a permanent fluid/lube.

 

[Benny1963]

Re: Cleaning Out Hydro-Electric Gearbox

hi jay i have had several of those gear boxs and or motors
i may still have a good one around for a 72 50 pm me if ya want it
i hope it didnt get scraped my son took some old blocks and stuff
to the scrap yard when the prices are up i will call him and see what i have left of the hydro stuff think i have some old control parts
will give them to ya if there still around ,was going to put some of this stuff on ebay but never did you can have them before they ruin also have some 1981 150 rotating stuff if ya have someone that wants it .your close to
.me so i can meet ya to give them to ya or bring them to no im in denham springs
i fish ponchatrain and the sulphur mine the texaco canals and on and on
glad ya came out alright ,i also used dexron to flush my hydro e lowers
but never ran them with just dexron

 

[jay_merrill]

Re: Cleaning Out Hydro-Electric Gearbox

Thanks Benny! See my PM.