First of all pardon my big truck ignorance. I have a 1989 F-700 low profile dump truck, I love the truck, except for when it breaks down. One question i have is what is this truck considered? Is this a 2-ton?
This isn't a ford question, its more of a hydraulic question, yesterday my father was driving it and dumping a load off and he blew a hydraulic line. I refilled the hydraulic tank and turned the pump on to try and see where the leak was and can not getting anything to happen. Would blowing a line and running it for a few seconds burn out the hydraulic pump? I hope not. Do hydraulic systems like this ever need any kind of bleeding? This stuff is all kind of new to me even though I have been running old ford trucks since i was 14 and been on this site for 10 years. Or does anyone know of a forum like this about hydraulics?
This truck has the 6.6 ford diesel and allison transmision, anyone have any thoughts on these drivetrain components? So far they have been great. I have had this truck for almost a year.

Tyler
89 F-700
'78 F-150 4x4 SWB 460 C6 Dana 60 f/r

 

There was just a thread about the "xx ton" designations. These are nominal, and an F700 could be 2 1/2 or 3 ton nominal designation. However, the GVW is based on axle, spring and tire combos, plus brakes, power, trans and is listed on the vehicle data plate, possibly on the door jamb.

Chances are, your truck will carry a great deal more than 3 tons.

Your dump hydraulics--what runs the pump? Electric?

Are there two controls? One to turn on the pump, and one to activate the valve which either allows oil to be pumped to the ram, lifting it, closing all valves allowing it to stay in place, either partially or fully up, and finally a valve that allows the pressure to bleed back into the tank so the bed can be lowered.

If the pump is running, but the valve is closed, you won't find your leak. If you open the valve, have an umbrella handy.

Working on a system like this is not a place for the uninitiated.

YOU MUST SUPPORT THE BED BEFORE DOING ANY WORK UNDER A RAISED BED. DEATH OR SEVERE INJURY WILL RESULT IF THE BED FALLS ON YOU.
Not just a 2x4 under there either. Something serious to hold that bed, with positive retention, and preferably two such supports.

You may be able to access some plumbing from under the truck.

Our '58 actually split open the square tube frame of the lift once. That tube was also the oil reservoir. Not sure how it happened, maybe the bed fell a little due to the load shifting and/or some backing up while dumping. Oil everywhere. Fortunately, it did not drop hard enough to break anything.

 

Actually the hydraulic system is a central hydraulics system run off a belt driven pump on the motor. The bed, the tailgate salter and auger and the 10' snow plow on the truck all run on the same hydraulic system. The leak is on one of the 3 lines going back to the tailgate salter which is not currently being used since its not quite snowing yet....... I can see the general area of where the leak is but i wanted to pinpoint it. And if i turned off the salter and the auger I would also be turning off the leak. My concern with the central hydraulics is that the pump is higher then the top of the resevoir tank and I am wondering if it somehow needs help betting it "primed" or "bled". The pump is turned on with a toggle switch. which has a wire going to the front of the pump, i assume that is like a a/c compressor, when it kicks in it engages the pulley to start pumping, when its not on i assume the pulley turns without using the pump. As far as handles I have 3 control boxes. On is a four way handle with up down left right movement for the plow. The second is up and down only for the box. And the third setup just has a up for on and a down for off for the salter/auger and this one has two dials on the side of the housing also to adjust the speed of the salter spinner and the auger rotation. I am going to try and go play with the truck today some more, i am going to replace the hydraulic filter although i doubt that is the issue, but it cant hurt. Any more input anyone might have would be appreciated. When I turn the switch on I hear a click at the pump pulley so i think that end of it is working, I just dont think the pump is pumping, either because its not "primed" or it is just burnt out. I wish I knew if these things burnt out easy or if you ever need to pime them some how

 

I wouldn't think it would burn out easily. It is, after all, covered in oil even if the oil is low. Is there a filler on or near the pump? Or a purge valve on or near the pump to bleed air?

 

i havent seen any type of purge valve. is that a common thing on these systems?

 

Don't know, just checking. Ours ran off the PTO off the trans, and was low. A purge valve would be one way to ensure you had fluid vs. air in a system where the pump is higher than the reservoir.

Check for a brand name on the pump, & google it. You may find a pdf with the whole instructions/blow up diagram etc.

 

Central Hydraulics, you can get at Harbor Freight Tools. I've seen those pumps, and looked like a good way to run a small system. Generally, with a drive or slave motor they self bleed. A ram needs to be bleed. It takes running for at least a min or 2 to trash the pump if it runs dry.
The 6.6 is a good little engine. Carry an extra set of belts if they're over 2 yrs old. Most complaints are about them being gutless, which you can remedy a little with the fuel screw, for up to a 30hp gain. The Allison is either an AT545(not too great), or an MT643/653(real durable). Neither are overdrive. They'll have an ID tag on the side of the trans case.