Eliminate the air/oil pump

[aw113sgte]

Got my vented pump cap. Removed all air lift and air/oil lines. Also took the safety valves out of the spare tire cylinder as I occasionally have it lock up.
Also checked out the manifold orifices and valves, all in great shape. All filter checked and clear as well.

Having an issue with overflowing the reservoir though I fill it up with the tire up and the cab down. I lift the cab up then let it go down and the reservoir overflows. I do it again and it overflows some more. I do it again and it overflows a third time. It is getting less each time but baffles me why it is at all. I can only figure there's some air in the system that's taking up room and causing the overflow? The other thing I noticed is when I let the cab lower due to gravity, I have to pump it probably 40 times before the cylinder is fully retracted. I could have sworn before it was just a few pumps for that to happen.

 

[GeneralDisorder]

Hhhmmm - have you rebuilt the air-over-hydraulic pump? Sounds like it's aerating the fluid and that's causing the volume to increase and it's efficiency to drop off.

When you say it takes 40 pumps to retract the "cylinder" are you referring to the latch locking pin? If things are working as designed gravity should pull the cab down once it crosses it's balance point and the latch should engage and retract it's locking pin on it's own. It shouldn't require any pumping at all if things are aligned and sealed and there's no air in the system.

 

[aw113sgte]

Hhhmmm - have you rebuilt the air-over-hydraulic pump? Sounds like it's aerating the fluid and that's causing the volume to increase and it's efficiency to drop off.

When you say it takes 40 pumps to retract the "cylinder" are you referring to the latch locking pin? If things are working as designed gravity should pull the cab down once it crosses it's balance point and the latch should engage and retract it's locking pin on it's own. It shouldn't require any pumping at all if things are aligned and sealed and there's no air in the system.

Air over oil is gone, totally removed from the system.

The cab lock engages, but it takes those ~30-40 pumps to draw down the cab cylinder until it hits a "hard stop" where the pump handle doesn't want to move and the cylinder is at it's retracted limit. No sponginess in the pump handle present.

 

[Ronmar]

Got my vented pump cap. Removed all air lift and air/oil lines. Also took the safety valves out of the spare tire cylinder as I occasionally have it lock up.
Also checked out the manifold orifices and valves, all in great shape. All filter checked and clear as well.

Having an issue with overflowing the reservoir though I fill it up with the tire up and the cab down. I lift the cab up then let it go down and the reservoir overflows. I do it again and it overflows some more. I do it again and it overflows a third time. It is getting less each time but baffles me why it is at all. I can only figure there's some air in the system that's taking up room and causing the overflow? The other thing I noticed is when I let the cab lower due to gravity, I have to pump it probably 40 times before the cylinder is fully retracted. I could have sworn before it was just a few pumps for that to happen.

I bet there is enough restriction somewhere, or there is leakage in the valve or pump or even around the rod end of the cylinder and it cannot pull enough vacuum to suck fluid thru the pump into the rod end of the lift cylinder as the cab lowers. Pretty common, hydraulic seals are great at holding pressure, but will leak when a vac is applied instead of pressure. Probably around the pump shaft/piston seal.

When you pump up the cab, it forces fluid back from the rod end as you pump fluid to the base end. If when you lower the cab, the rod end doesnt suck its fluid back, as the base end forces fluid back this will increase the volume in the pump reservoir.

This should stabelize at some point and stop expelling fluid.

You dont want to fully retract the cab cylinder. Ideally you want to let the cab lower into the deflated cab suspension. Then when you inflate the cab suspension the cab attach rod will ride up and down in the long slot. I did a video showing this on utube, usrename Rronmar. There is no float position for the cab lift hydraulics, and if pulled in too far, the cab riding on its suspension will stress the cylinder or mounts...

 

[GeneralDisorder]

There is no need to retract the cylinder. Once the cab latches and the pin retracts you can stop.

 

[aw113sgte]

So with a vented cap on the pump, what's to stop the spare tire cylinder from leaking into the reservoir due to gravity?
Edit: looks like as long as there is no air leak and the reservoir level remains above the return port, it can't.

View attachment 910616

 

[aw113sgte]

I bet there is enough restriction somewhere, or there is leakage in the valve or pump or even around the rod end of the cylinder and it cannot pull enough vacuum to suck fluid thru the pump into the rod end of the lift cylinder as the cab lowers. Pretty common, hydraulic seals are great at holding pressure, but will leak when a vac is applied instead of pressure. Probably around the pump shaft/piston seal.

When you pump up the cab, it forces fluid back from the rod end as you pump fluid to the base end. If when you lower the cab, the rod end doesnt suck its fluid back, as the base end forces fluid back this will increase the volume in the pump reservoir.

This should stabelize at some point and stop expelling fluid.

You dont want to fully retract the cab cylinder. Ideally you want to let the cab lower into the deflated cab suspension. Then when you inflate the cab suspension the cab attach rod will ride up and down in the long slot. I did a video showing this on utube, usrename Rronmar. There is no float position for the cab lift hydraulics, and if pulled in too far, the cab riding on its suspension will stress the cylinder or mounts...

It wouldn't shock me if the pump had some issues. It was clear the shaft was painted over and then the pump used so that paint may be in the seals causing a leak. New pump is on order. Will try to rebuild this one too, looks like there is a retaining circlip or similar on the bottom.

 

[ramdough]

I am on my second stock manual pump and that is leaking too. First one failed quickly.


I bought the one [mention]Ronmar [/mention] used. New pump, new seals, new reservoir, fewer pumps…..

I have yet to install the new one, but I think that is a better way than what you are doing.

Just a suggestion. Get a new pump…..


Sent from my iPhone using Tapatalk

 

[aw113sgte]

I am on my second stock manual pump and that is leaking too. First one failed quickly.


I bought the one [mention]Ronmar [/mention] used. New pump, new seals, new reservoir, fewer pumps…..

I have yet to install the new one, but I think that is a better way than what you are doing.

Just a suggestion. Get a new pump…..


Sent from my iPhone using Tapatalk

Yeah may regret not buying a new one, tune in to find out!