Hydraulic pressure test done - it's way low - now what?

[Teikas Dad]

I finally had a chance to do my system pressure test yesterday. I worked the tractor for an hour or so to make sure everything was warmed up to operating temperature. Disconnected the rearmost hydraulic connector on the FEL and plugged the gauge in there.
Ran it up to 2500 RPM and tested - 4 times - Run it up then to zero, back up, to zero, etc. Factory spec calls for 2090 to 2200 PSI on the system. I consistently got 2050 PSI so I'm low. The gauge kit came with 3 spacers - a .10, .20 and .30mm. The only thing I can't find and I've searched everywhere online and here on the forum is how many PSI each thickness spacer will raise the pressure. I've seen BX info that shows about 30 PSI per .10mm spacer but I can't find anything on a B3200 (or B3300 - same basic tractor). Would the spacers raise the pressure the same amount on a B3200 as on the BX series or is the whole process trial and error?

Also, I found that there was a slight leak on the female connector on the gauge. Nothing squirting out while under pressure, just some weeping - maybe a tablespoon worth of fluid if that with the full test cycle. Would that have any impact on my pressure reading?

 

[k0ua]

Also, I found that there was a slight leak on the female connector on the gauge. Nothing squirting out while under pressure, just some weeping - maybe a tablespoon worth of fluid if that with the full test cycle. Would that have any impact on my pressure reading?

To the best of my knowledge the shim procedure is trial and test. The weep will have no impact on your pressure reading. But be very careful around any hydraulic leak as you may not be able to see a very small high pressure leak. They are VERY dangerous if you get your body near them. Hydraulic injection is no joke. Just google it to be grossed out.

 

[Dave M7040]

I finally had a chance to do my system pressure test yesterday. I worked the tractor for an hour or so to make sure everything was warmed up to operating temperature. Disconnected the rearmost hydraulic connector on the FEL and plugged the gauge in there.
Ran it up to 2500 RPM and tested - 4 times - Run it up then to zero, back up, to zero, etc. Factory spec calls for 2090 to 2200 PSI on the system. I consistently got 2050 PSI so I'm low. The gauge kit came with 3 spacers - a .10, .20 and .30mm. The only thing I can't find and I've searched everywhere online and here on the forum is how many PSI each thickness spacer will raise the pressure. I've seen BX info that shows about 30 PSI per .10mm spacer but I can't find anything on a B3200 (or B3300 - same basic tractor). Would the spacers raise the pressure the same amount on a B3200 as on the BX series or is the whole process trial and error?

Also, I found that there was a slight leak on the female connector on the gauge. Nothing squirting out while under pressure, just some weeping - maybe a tablespoon worth of fluid if that with the full test cycle. Would that have any impact on my pressure reading?

I may be wrong but, I think you are focusing on the wrong relief valve. Most loader valves have their own relief valve built in. If I am correct that is the relief valve you have just tested.

Do you have power steering as I cannot find any manuals specific to your tractor and tractordata.com shows no earlier nor later models..

How many hoses connect to your loader valve? 6 or 7.

Before you go adding any shims I suggest you/we need to fully understand your system and where you are adding shims.

Be patient, increasing by 50 to 140 psi wont make a difference you will likely notice! You don't get a second chance with hydraulics. In an instant something is broken beyond repair.

Dave M7040

 

[LouNY]

Static pressure testing of a hydraulic system just shows what the reliefs are doing.
It does not check for pump wear, that testing requires a flow meter.
If your tractor is rated for 8 gallons per minute at 2200 psi and you get 2 gpm at 2100 it would point to a wore out pump.
If you are getting 8gpm but only 1200 psi it points to a relief valve.
With your relief holding at 2050 psi dead headed that still doesn't tell you what pressure the relief starts to relief at,
many times it will take more pressure to unseat a relief then to keep it unseated. In other words it could take 2150 psi to start relieving but it will not reseat till less then 2050 psi.

 

[Jeff F.]

I tested my B3200. I used the same method as you and I have the same results. I was also thinking of shimming it up to the max. I will be following your thread.

 

[Teikas Dad]

I may be wrong but, I think you are focusing on the wrong relief valve. Most loader valves have their own relief valve built in. If I am correct that is the relief valve you have just tested.

Do you have power steering as I cannot find any manuals specific to your tractor and tractordata.com shows no earlier nor later models..

How many hoses connect to your loader valve? 6 or 7.

Before you go adding any shims I suggest you/we need to fully understand your system and where you are adding shims.

Be patient, increasing by 50 to 140 psi wont make a difference you will likely notice! You don't get a second chance with hydraulics. In an instant something is broken beyond repair.

Dave M7040

Thanks for the input Dave. The B3200 is a hydrostatic tractor. The relief valve in the loader is the one I'm looking for. BXpanded included directions specifically showing how to run the test and what valve requires the shims to be added. However, they don't tell you how many PSI each thickness shim corresponds to. I just saw a post from someone with a B3300 - basically the same tractor as the B3200 and he got a boost of 80 PSI with a .2mm shim. If the math is correct then I'm planning on using a .3 and .1 shim to equal 160 PSI increase. I'll test it again after adding the shims. If it's too high then I can take the smaller shim out and retest.

 

[Jeff F.]

Please keep posting your results

 

[Teikas Dad]

Please keep posting your results

Will do.

 

[Teikas Dad]

Static pressure testing of a hydraulic system just shows what the reliefs are doing.
It does not check for pump wear, that testing requires a flow meter.
If your tractor is rated for 8 gallons per minute at 2200 psi and you get 2 gpm at 2100 it would point to a wore out pump.
If you are getting 8gpm but only 1200 psi it points to a relief valve.
With your relief holding at 2050 psi dead headed that still doesn't tell you what pressure the relief starts to relief at,
many times it will take more pressure to unseat a relief then to keep it unseated. In other words it could take 2150 psi to start relieving but it will not reseat till less then 2050 psi.

Thanks for the input Lou. My tractor only has 80 hours on it so I'm hoping that Kubota built the pump to last a bit longer than that! I hear what you're saying about pressure to unseat the relief valve but wouldn't that show a quick spike on the gauge when the pressure is applied then drop back to the max sustained reading? I held the valve open for 15 seconds or so to let the system settle and when I had several seconds of the gauge not moving any higher I released it.

 

[LouNY]

depending on damping either built into the gauge or an added on snubber you may or may not have seen the initial peak,
if the control valve was gradually opened you could have possibly seen the pressure peak just before the relief opened.
When using the older flow rater that IH had you would get the flow loop established then start restricting flow and watching your system pressures,
that way you would know what everything was doing. Many of your older shops independent and dealer should have such a unit.
The newer ones look like this;
IH Farmall Hydraulic Flow Rater Tool 3gpm 4psi - Redrunrite