:confused2:Pressure relief valve issue ( I think )

[Tim Stuart]

I need some help with my old Mahindra 575 Di , I just put in a brand new hydraulic pump, new hydraulic screen / filter, and new fluid . I also replaced the rubber hose on the suction side of the hydraulic pump. The loader now functions with good speed but will only lift about a half of bucket of dirt. The loader arm will also stay up fully extended for 2 days. The way that the loader is set up on my tractor is suction side comes in from the strainer / filter into the new pump, than the discharge side of the pump goes directly to my loader joy stick. (No lines were disconnected from the joy stick during this), than the lines go to the loader cylinders, one line goes back to the tractor hydraulic assembly under the seat where the filter / strainer is and the cycle starts over. I am thinking I have a pressure relief valve issue. During the trouble shooting process of the pump problem, a friend pulled the pressure relief valve apart and I am not sure if he got it back together correctly. Now for my questions.


1 Does this sound symptomatic of a defective pressure relief valve?
2 Does anybody know what kind of loader valve this is in the picture below?
3. Can I just replace the pressure relief valve?
4. Can the relief valve be rebuilt?
5. Is it worth rebuilding or just trash it?


I know buy a pressure gauge!!!!. The hydraulic lines have a O-ring fitting that a 15/16 wrench will fit, Does anybody know what kind of fittings these are more than likely are and where I can get a good deal on a pressure gauge (5000 psi correct?) from what that will it into the lines>

Thanks in advance,

Tim

 

[J_J]

If your pressure is coming into the valve from the right side, then that valve beside the handles, with a small protrusion, is probably your relief. If someone took it apart, it could be out of adjustment. A pressure gage is necessary to set the relief up correctly. First you have to know the pump pressure, and set the pressure about 50 to 100 psi below the max pump pressure. If there are shims, then add shims as necessary to set the relief.

https://www.surpluscenter.com/item.asp?item=21-1044&catname=hydraulic

 

[kennyd]

I know buy a pressure gauge!!!!. The hydraulic lines have a O-ring fitting that a 15/16 wrench will fit, Does anybody know what kind of fittings these are more than likely are and where I can get a good deal on a pressure gauge (5000 psi correct?) from what that will it into the lines>

Thanks in advance,

Tim

Yes, any further diagnosis will require a gauge. Surplus Center has them for under $20, also get a 36" piece of hose. You will need to measure the threads on your fitting to verify...but it sound like it might be a SAE -8 ORFS (O ring face seal) fitting.
Thread Chart and Better Thread Chart

1 Does this sound symptomatic of a defective pressure relief valve?

Yes

2 Does anybody know what kind of loader valve this is in the picture below?

No

3. Can I just replace the pressure relief valve?

Only if you can identify the brand and model of the valve.

4. Can the relief valve be rebuilt?

Yes

5. Is it worth rebuilding or just trash it?

Definitely try to set it with a gauge first.

 

[Tim Stuart]

J.J. and Kenny, Thank you both for your fast response. I drug out my book to check my pump psi and flow, Book says 2200 psi + or - 10 % wih a flow of 8.24 GPM. I went to order the pressure gauge from the link, I liked the price of the item $17 but choked on the shipping cost of $11 of UPS ground.
(Have they every heard of the USP if it fits it ships) I think I can pick one up local in Houston and not have to wait. I had one more question- I have highlighted a pulg in the picture below, Can this spot be tapped into for a power beyond or rear remotes?

Thank you again!!

Tim

 

[J_J]

Are there any letters by the plug? Does it have PB or an R? It looks like another return port.

 

[kennyd]

I had one more question- I have highlighted a pulg in the picture below, Can this spot be tapped into for a power beyond or rear remotes?

Thank you again!!

Tim

I doubt it, it is probably just a duplicate of the port on the side of the valve so if the installation prohibited the use of the side port the top one could be used and the side one plugged. Add to that...if it was a PB port (usually marked BYD) you probably would have trouble locating the correct plug for it since it's an old valve and you don't know the manufacturer.

 

[wdchyd]

Tim,

JJ mentioned shims, when this was taken apart 1 or 2 shims could have fallen out or maybe just not put back together the same?