dump bed problems

toodie · Jul 21, 2012

I have a 73 ford with a dump bed.the problem is: when the bed is lowered it is building pressure in the system and leaking out of the fill plug.it is a system without a resevoir tank.it is driven off of a pto pump. can anyone help trouble shoot this system?? all help is appreciated!!!

IaGary · Jul 21, 2012

Is the system set up for the oil to return to the top side of the clinder when it is in the down position? The oil has to go somewhere.

If it does return to the top side is there a way to bleed air out? You may have air in the top side.

You said out the fill plug. What are you filling?

It may be over full if the cylinder still lifts all the way. Have you cylced it a few times without adding oil to see if it still lifts all the way?

I know more questions than answers, right.

Gary

Dave Sherburne NY · Jul 21, 2012

On our Mack, in order to get to the fill pipe the box has to be raised. BUT if you fill the reservoir to the top it's to much and the oil comes out the fill pipe when the box comes down.
The cylinders are single acting so all the fluid has to go back in the reservoir.

Mike Kork · Jul 21, 2012

Probably overfilled if you filled it up with the bed raised.
You check the fluid level with the bed down.

evilboweviel · Jul 21, 2012

used to drive dump trucks back in the early 70's with a Marion hoist single cylinder that had to have the bed raised up to fill with oil
you left the plug out and cycled the bed up down a few times then put the plug back in
Good luck
Ron

old · Jul 21, 2012

On those systems you have to fill the what they use as the tank with the bed down. If you fill and or check with the bed up that will cause just such a problem. I learned that the hard way on my Ford dump truck and had it get where the bed would not go down due to an over fill tank

KSTractor · Jul 21, 2012

Is your PTO running when you are lowering the bed ? some systems need to go down under power so the oil is pumped back to the other side of the cylinder

toodie · Jul 21, 2012

I bled system down/with bed down, slowly filled untill bed was in raised position,still has fluid coming from fill plug

toodie · Jul 21, 2012

I have tried both ways.it seems to have the fluid coming from fill plug both ways

toodie · Jul 21, 2012

I filled in raised position once lowered bed with plug in,it seemed to have pressure,so I cracked the fill plug to bleed off air.still had the same problem

toodie · Jul 21, 2012

this has no tank or resevoir.I fill it enough to get the bed to raise,and when you let the bed down it still has the fluid coming out of the plug

toodie · Jul 21, 2012

I cannot see a way to bleed cyl.the only thing on cyl is a tag with two bolts on the piston side.is that a cover for a bleed valve??

toodie · Jul 21, 2012

I filled with bed down.slowly filled untill bed was in dump position.

evilboweviel · Jul 21, 2012

if you fill it full with the bed raised and then put the plug in it will have pressure when in the down postition.
leave the plug out and raise it and lower it 3 times then put the plug in
good luck
Ron

Rollie NE PA · Jul 21, 2012

If the cylinder has a pipe plug, drill 1/8 hole in it so it can get some air. Put a cotter pin in the hole that is smaller than the hole you drilled. Works for me.

o · Jul 21, 2012

Slowly filled till bed was in the raise position is your problem. It has to but full with the bed down and if the bed is up and full it is over filled

old · Jul 21, 2012

Slowly filled till bed was in the raise position is your problem. It has to but full with the bed down and if the bed is up and full it is over filled

Janicholson · Jul 21, 2012

If it has two hoses going to the cylinder, the top of the cylinder is used as a reservoir.
If it has only one hose, the system needs a reservoir to supply enough oil to lift and a place for it to go when down. Many reservoirs are available from places like northern tool.
the top of the reservoir shouild be at or above the fill plug, which now becomes connected to the reservoir bottom with a hose.
To see if this is a cure, connect a hose (with a fitting) to the fill hole, and stick it into a container of the lift oil. If it now cycles correctly, a reservoir, with vent is your answer. Jim

Errin OH · Jul 21, 2012

What are you putting in it? The guy I got my hoist from said he always used transmisson fluid. Problem with it is it tend's to foam up with alot of use. I'd cycle it with the plug out and see if it is foaming up on you and pushing fluid out in the process.

Also just were is this plug? I have an electric pump with can mounted on it, about a quart or so reserve on it, the rest of the fluid needed to raise it all the way up in the other side of the cylinder. Reason for the quart or so is to make up the difference between the side with a rod taking up space in the cylinder and the lift side with no rod, plus expansion of the fluid as it warms up.

Dave Sherburne NY · Jul 22, 2012

Can you get us a picture of this rig???

toodie · Jul 22, 2012

I will try to get a picture.the pump has two plugs.if I fill thepump in lowered position,the bed will not go up.it acts like when the bed is lowered the relief valve is stuck,but there is no valve on this truck.

Waltmo · Jul 22, 2012

Sucking air from hose to the other end of cylinder?
WaltMo

toodie · Jul 22, 2012

toodie · Jul 22, 2012

(quoted from post at 23:16:59 07/22/12)

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toodie · Jul 22, 2012

no hoses,it has a pipe from bottom of cylinder to top.the horseshoe cast iron piece takes the place of hoses to the pump.I have never scen a setup like this!!

dump bed problems

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