BX hyd pressure - can't get below 2,000psi

[fish6942]

Like the saying goes "if it ain't broke, fix it 'til it is".

A while back I picked up a pressure gauge to test the pressure relief valve setting on my BX2350. It was reading about 1,700psi so I got some shims from the dealer to bump it back up closer to the 1,850 max setting.

I put in 0.3mm of extra shims hoping to get a new pressure of about 1,820 (0.1mm ~= 39psi). Surprisingly, the pressure jumped to 2,500.

Not knowing why it jumped so high, I removed the shims I added and retested. Pressure stayed at 2,500.

Now what... So I then removed the two shims that came with the machine from the factory (I purchased it new) and the pressure dropped to 2,000. (remember I started at 1,700)

One thing that I found interesting was there is no torque spec for the plug used to access the spring/shims. However, it sure would seem that engaging the plug an extra thread should have the same effect as adding more shims?? As a test, I loosened the plug and just hand tightened it. Even with the plug in just a minimal distance, the pressure remained at 2,000.

I did check for particles under the shims and the spring.

Note - All pressure measurements were made on the loader ports with the engine at 3,000 rpm.


Any ideas as to why I can't get the pressure back to at least where I started?

 

[Jimbrown]

The gauge is broke?

 

[radioman]

Perhaps one of quick disconnects is not seated fully. Otherwise gauge could be broken

 

[Scooby074]

Gauge broken.

Something stuck in the RV keeping it partly closed?

 

[fish6942]

Gauge broken. Something stuck in the RV keeping it partly closed?

Far as I can tell the gauge is fine. After taking a measurement I ways run the joystick the opposite direction and the gauge drops to near zero.

I'm assuming the cartridge looking thing that the spring pushes against is the relief valve? If so, can I just reach in there with a needle nose and pull it out?

 

[Scooby074]

Far as I can tell the gauge is fine. After taking a measurement I ways run the joystick the opposite direction and the gauge drops to near zero.

I'm assuming the cartridge looking thing that the spring pushes against is the relief valve? If so, can I just reach in there with a needle nose and pull it out?

The attachment shows what your relief/pump looks like.

Section "B" is your relief. I wouldnt go rooting around in there with pliers willie nillie. There are machined surfaces in there, do not scratch in other words. You need something soft. Even a magnet will likely be enough to remove the seat and poppet (#80 and 90).

While I was at it Id probably pull apart section A, the priority valve as well.

Watch what you use to clean it out. Brake Clean can damage Orings so be careful if you use it. A tiny spec of dirt can be enough to hang things up

 

[J_J]

You should remove all parts in the relief valve and reassemble with original shims.

Recheck the pressure, and adjust accordingly.

You might also try installing the gage in a tee in the IN port to check the total hyd system.

 

[fish6942]

Alright guys, I'll take the PV out first and have a close look at it. Unfortunately it won't be until Sunday... Thanks for the help so far!!

 

[Xfaxman]

Like the saying goes "if it ain't broke, fix it 'til it is".

A while back I picked up a pressure gauge to test the pressure relief valve setting on my BX2350. It was reading about 1,700psi so I got some shims from the dealer to bump it back up closer to the 1,850 max setting.
--------------------------------------------------------

Note - All pressure measurements were made on the loader ports with the engine at 3,000 rpm.
------------------

You can check the pressure at idle, the relief valve should open, unless the pump is badly worn, which yours isn't.

 

[fish6942]

Alright, I got into the PRV a little more and was able to remove the poppet (item 90 in Scooby's IPL above) using my magnetic retrieval tool. Nothing looked out of the ordinary and there was no obvious debris that I could see inside the housing. The tapered surface of the valve body looked clean as well.

However, I was not able to get the valve body (item 80) to come out. I was able to hook an allen wrench inside the body but it wasn't budging. Not sure if there is a technique involved with getting this out but realistically, I'm also not sure if it is that important at this point.

I also removed the priority valve body and found nothing there either.


So after all this, nothing has changed on the pressure (didn't expect it to). It is still right around 2,000psi. I also put the gauge on the other loader ports and got the same readings.

Is it possible that something about the spring from the PRV is causing this?

Also, I went back and reconfirmed one of my earlier tests. With the PRV plug barely installed, the pressure test gives the same results as when the plug is fully tightened. I would have expected the additional turns to have a similar effect as adding shims. Any ideas on that?