I'm having the same problem.
Did you ever find the problem ?

Hi There swoop223,

Last night I swapped the system relief valves for test port #1 and test port #2 just to see if the low pressure on test port #1 would transfer to test port #2 and it did not make a difference, the low pressure is still on test port #1.

I see on the Hydraulic schematic that test port #1 is fed by section #1 of the hydraulic pump and it also feeds the Generator Manifold so I connected together the two hydraulic lines on the Generator Manifold to bypass the Generator completely and still have low pressure on the test port #1.....

Right now I have over 3500 PSI on each section of the pump and 600 PSI on test port #1 and 3500 PSI on test port #2....

Hmmm

Awesome, thank you so much

each test port has a specific area or set of functions it is connected to
if you go into the service manual and go to the repair procedures and navigate to Manifolds there are sections that deal with valve adjustments. Each explanation tells you which port to connect to during the function test you want to test pressures on and adjust if needed.
system relief connects to ports 1 and 2
Steer relief connects to port 2
lift relief connects to port 1

so yeah it sounds like somethings going on if port 1 is low
i wish the manual went into more detail about both ports and their relation to the drive system. I can call genie and talk to an engineer and see if they can shed any light on it.
I'll see what i can find out and get back soon.

Hi Swoop223,

I'm back; I was gone for a few days.... Now back to my Scissor lift

When I told you the pressures were good I did not check them at the test ports the place I checked the pressures was right at the discharge of the pump and each section was 3500+....
I just now checked the pressure at the test port 1 and test port 2 and here's what I found, test port 2 was 3500 PSI going forward or reverse and test port 1 was 600 PSI going forward or reverse... it sounds like something is up with port 1? Yes?

awesome! thank you so much! Great Info again :-)


Todd

since that system does not have a traction manifold with flow/combiner valves I'm not sure if i would cap the lines. I would use a straight connector and hook the pressure and return together so the fluid will pass through. If you have problems getting the system to gain pressure in the drive with the lines connected this way then you can try to cap them but be very careful about how much pressure you apply through the drive control. I would be afraid the pressure would build in the pressure line and cause it to rupture. You can use a cap on the bleedoff return line If there is one. It's a small 3rd line that ports overflow bleed back to the tank, some newer units have this. Yours might not, i see it in the schematic coming off the left and right rear motors but not on the front motors. There should also be a brake line on the L & R rear motors, you can cap that one as well.

would it hurt the lift if i disconnect and cap all hydraulic lines on just that motor? then drive it with three drive motors just to see if it makes a difference?

when UPS delivered the drive motors last week Genie put both drive motors in one box and it split wide open and the box was VERY HEAVY! im sure at least one or maybe both motors hit the ground.

box was in very poor condition, wide open....


Todd


Todd

you can pull the motor off and see if something is assembled wrong causing it to bind up?
You may have to remove the nut holder on the outside of the hub on that wheel to get the motor come come out.
If the motor does not move at all it sounds like something is binding it up.

Hi There Swoop223,

Yesterday I removed the check valves and they seemed fine, no obvious problems? you are right it will make a mess, thanks for the heads up. My Lift does not have shut off valves on the suction side of the pump, I followed the suction line from the tank to the pump with no luck.

anyways I'm still stuck on the right rear wheel that will not turn by hand, the other three are hard to turn but I can turn them, the right rear not at all.....

Swoop223,

Thank you for your help, I will be looking at the check valves today.

Todd :-)

Todd,
i do find it odd that 2 drive motors would be bad at the same time, one maybe but both?
I'm still in the opinion that the problem may be in the control valve manifold, maybe with the directional solenoid valves or maybe one other check valve associated or a counter-balance valve.
remember, if the circuit is not activated and all valves are closed you get no path for the fluid to go so the motors will not want to turn, your moving the motor against itself which is why they do not want to move. With the unit 'not running' all motors should be this way and have a lot of resistance to them. Not to mention the brake valve being engaged should have all of them locked down unless you have the manual brake release pumped up and in brake release mode.
the fact you have one side of the circuit still allowing the wheels to turn freely when the unit is not running tells me there is some issue causing the circuit to remain open.
Let me do some checking and see if i can come up with some other tests for you to help narrow down what is causing this.
_______
I went over the hydraulic schematic and the circuit associated with the right front and left rear is associated with drive valve B. Now there are 2 check valves in the drive circuit, valves L and N on the component call-out legend in the service manual. I would pull those out and check them as well.
You will need that schematic and function valve diagram and the call out legend so you can locate the check valves.
Note: you may already have become aware of this but i will remind you that this hydraulic system has a tendency to gravity feed oil from the reservoir when lines and valves are removed and can make a huge mess of oil and literally drain the majority of oil from the tank if left in this state. There should be a one or two(in some cases) gate valves located near the reservoir you can shut off that will help stop this. They should be inline with the suction hose(s) feeding the main pump. It will still have a tendency to still drain out (from the return side lines etc) but not near as much. Just make sure you have a container to catch the oil.

Hi there swoop223,

One other thing I noticed is with the scissor lift jacked up, all 4 wheels off the ground and the brake released, with the engine off the right front and left rear wheels turn by hand, the left front is very hard to turn and the right rear will not turn at all. these are the 2 new drive motors that the Genie Service tech told me I need to replace, whatever the problem is now might be why the 2 drive motors went bad?
I'm still checking out the 3 position 4 way valves that controls the flow to the drive motors, I checked for power at the coils and that seems ok at the proper time.....

With the engine off and no pressure shouldn't the wheels turn freely with the brake off?


I checked the pressures at the function manifold test ports and all are good.

Front = steering end
right = engine side
left= lower controls side

Wow,
Thank you very much swoop223,
Thats a ton of great information, that gives me a lot of thigs to check out.

I very much appreciate that
Todd ??

Todd,
if your having drive problems and the wheels do not seem to be pulling correctly you'll need to use a 5000 psi pressure guage and check the pressures on the drive manifold. It should have a diagnostic nipple port on the side of the function manifold to check pressures.
System relief (pump1) = 3500psi
System relief (pump2) = 3500psi
Lift relief (model GS-2668RT) = 3500psi
Lift relief (model GS-3268RT) = 2000psi
Steer relief = 1500psi

Now one thing i would do is check the valves for bad orings or damaged or stuck plungers.
Alot of the time orings will go bad and cause a pressure bleed over into other hyd circuits and create pressure issues with these other circuits causing them to malfunction.

There are 2 valves that control the oil flow to these motor circuits and it sounds like one of them is bad.
On the function manifold schematic it shows Valve A as follows:
DO3 valve, 3 position 4 way - A - Controls flow to the steer end
ground controls side drive motor
and the non-steer end engine side
drive motor in forward and reverse
And
DO3 valve, 3 position 4 way - B - Controls flow to the steer end
engine side drive motor and
the non-steer end ground
controls side drive motor in
forward and reverse

These 2 valves are the large valves mounted on 2 blocks on the function control valve, they have solenoids on both ends.
The manifold block should have stamped in it the valve letter designation A or B.
If you need the service book on it you can go to genie's website and download it, it is free to get for the public. it has everything you need to help identify where on the manifold these components are.

Hey thank you Swoop223,

A genie service mechanic from the local dealer came and checked out my lift, he told me the left front and right rear drive motors need to be replaced, so I ordered and replaced them and it seems worse, it has LOTS OF RESISTANCE when it drives, almost like it has the brake on but it dosen't.

I'm going to check for something in the manifold, with it jacked up if I start to raise the platform the left front drive wheel starts to turn??????

Todd

hey Todd,
your unit doesn't have the hub lockout caps then it will have a brake release mechanisim.
The hub lockout caps were not used on this model, only a hex nut lock cap that holds the nut for the hub onto motor assy.
If you want to move this unit if it is not drivable then you'll have to use the manual brake release.
The brake release hand pump manifold is mounted at the non-steer end of
the chassis on the ground controls side of the machine.

Hi there,

Swoop223, does my 4x4 GS 2668 RT have the lock out mechanism on the hubs also? I dont see the cap with the dimple on it.... Do you have pictures?

Model : GS 2668 RT 4X4
Serial : GS6805-44399

Thank you
Todd

Thank you so much for your valuable info. I'll try to drive it that way just be able to bring it to get it fixed. I'll keep you updated. Thank you again.

you can drive it around but i would recommend locking out that motor using the lockout mechanism on the hub of the wheel in question.
If you look at the drive hub there is a cap with a dimple on it, has two 1/4" bolts holding it on. Take it off and flip it over with the dimple pointing inward. Once you get it off you'll see a release pin inside, that dimple pushes on that and unlocks the gears inside the drive hub.
I wouldn't recommend driving it this way except only to move it from one area to the place you're going to repair it. Do not drive it like this full time. With a bad drive motor you will experience problem driving it over terrain or up hills etc.
There could also be something wrong with the drive manifold causing that issue. You need to get a 5000 psi pressure guage and test pressures on the drive system and make sure all the pressures are correct according to the manual. Also checking drive motors and the drive manifold valves can be a task to do, and can get messy.
if you're not a genie tech i would strongly recommend calling one in for this.