M817, problems with PTO, need advice.

[Jwilson2500]

I bought this truck as a tractor. I purchased a parts m817. I took the bed; pto; levers; linkages and winch off and transferred it. I got it fired up today for the first time, went to dump the bed and the cylinders leak terrible. I am having them rebuilt tomorrow. I noticed that the pto will never disengage. Is this normal for this truck to constantly spin the driveshaft to the hydraulic pump while driving down the road? Thanks, John.

 

[someoldmoose]

Since nobody jumped into the shallow end headfirst, here goes. Had a LOOOOOOOOOOOOOOT of stuff (trucks, tractors, even trailers ) with PTOs on 'em. And 'cept for a Fire Truck that would Pump n Roll and one that has a "hydraulic" generator, have never known one that was supposed to be engaged while driving normally. On this set-up I don't know that it would "hurt" anything as long as the system is flowing freely and properly, JUST UNNECESSARY WEAR & TEAR ON ALL THE COMPONENTS. I would suggest checking the shift mechanism first and if that works ok, it COULD BE "STUCK" in due to wear, or a torque lock type sitch.

Not a solid "what ya oughta do" but decades of experience being shared with you.

 

[Floridianson]

If you find your missing linkage parts let me know I have 6 m817 parts trucks. Parts are free just pay shipping.
You did grab the lever and all the linkage that is behind to the left of the drivers seat?

 

[Jwilson2500]

I had to make one that goes behind the seat I would like a original if you have it

 

[Floridianson]

I have to go this week to the property where the trucks are and start to strip them off. Will pm you later.

 

[Jwilson2500]

Did any of them have a winch I need the pto lever and linkage to run the pto

 

[CGarbee]

As mentioned above, as long as the valves are in good shape, you can go down the road with the PTO spinning the pump and it will be ok...but you are putting a bit of faith in the system and adding a lot of wear to things.
The linkage setup that controls the dump up/down/hold function is combined with the one that controls PTO on/off...so you only have to work the one lever between the driver seat and the door to operate the dump.
The problem is that as the system gets worn, and/or just plain out of adjustment, it gets hard to: shift the lever, have the bed move up and down as it should, have the PTO engage/disengage as it should.

One thing to do before you even start adjusting the links is to grease everything making sure that you clean out the square box with the "fingers" in it that control the valves and the PTO link and put in fresh grease...

My setup is so worn on my M817 ('71, former National Guard truck) that I have acquired the parts needed to convert the PTI to pneumatic control while leaving the hoist controls as is so that I only have to get half of the system dialed in and so that it acts more like a civilian truck for when I loan it out to friends/family...