l455 pressure test results

[NHL455]

so my test kit arrived today and when i connect up to the main bucket cylinder i get an initial surge to about 15-1600 psi and then it drops immediately to 1000psi and just remains at 1000psi then if you let the pedal off and press it again the same happens shoots up to 15-1600 psi and then drops immediately to 1000 and stays at 1000 constant?

 

[NHL455]

just realised the test kit was leaking slightly so i tightened it up and retested and the needle is now going to 2000 PSI and then dropping down to 1000PSI then if you pump the pedal it goes back up to 2000 psi and then drops ?

 

[Tazza]

just realised the test kit was leaking slightly so i tightened it up and retested and the needle is now going to 2000 PSI and then dropping down to 1000PSI then if you pump the pedal it goes back up to 2000 psi and then drops ?

How are you testing it? are you installing the gauge in parallel to one port? as in installing a T
Skid steer systems seem to have pressure on the ports even when you're not enabling the pedals, so the 1,000 PSI could be from that.

 

[NHL455]

How are you testing it? are you installing the gauge in parallel to one port? as in installing a T
Skid steer systems seem to have pressure on the ports even when you're not enabling the pedals, so the 1,000 PSI could be from that.

i removed the feed pipe to the main bucket cylinder and connected this to my gauge - i do not have a T connector. however before i pressed the pedal to activate the pipe leading to the cylinder it was not reading any pressure in the system

 

[NHL455]

i removed the feed pipe to the main bucket cylinder and connected this to my gauge - i do not have a T connector. however before i pressed the pedal to activate the pipe leading to the cylinder it was not reading any pressure in the system

just for background my boom and bucket lift up and down ok but cannot lift any weight - so trying to determine what the problem is ?

 

[Tazza]

just for background my boom and bucket lift up and down ok but cannot lift any weight - so trying to determine what the problem is ?

Ahh, so you should get full pressure from the control valve to the gauge, ruling out the cylinder.
Do you have aux hydraulics on this machine? this is a common symptom of them being stuck on. Some functions work, others will not. Ensure they are not stuck on causing your problem.

 

[NHL455]

Ahh, so you should get full pressure from the control valve to the gauge, ruling out the cylinder.
Do you have aux hydraulics on this machine? this is a common symptom of them being stuck on. Some functions work, others will not. Ensure they are not stuck on causing your problem.

yes def not cylinder as had an expensive rebuild, yes i do have aux hydraulics - but i have used skid with attachments with the aux hydraulics connected up and still have no lift power - and if the aux hydraulics were stuck on wouldnt i see the brush spinning or wouldnt the 4 in 1 bucket keep opening or closing ?

 

[Tazza]

yes def not cylinder as had an expensive rebuild, yes i do have aux hydraulics - but i have used skid with attachments with the aux hydraulics connected up and still have no lift power - and if the aux hydraulics were stuck on wouldnt i see the brush spinning or wouldnt the 4 in 1 bucket keep opening or closing ?

Yeah, if it was stuck on, the bucket or brush cutter would move.
Just thinking out loud, I know bobcat had relief valves mounted into the lift and tilt sections of the control block. I wonder if it's one of them or a load check causing the issue. I'd like to think that the gauge wouldn't move or move very slowly after being dead headed like you have done for a test. It has to be the control block, surely?
Each segment of the control block has a spool, in line with this spool, you have two ports to let oil out to either end of the cylinder, in this same line, there will be plugs with load checks behind them or small relief valves. Hopefully the issue is in here....

 

[NHL455]

Yeah, if it was stuck on, the bucket or brush cutter would move.
Just thinking out loud, I know bobcat had relief valves mounted into the lift and tilt sections of the control block. I wonder if it's one of them or a load check causing the issue. I'd like to think that the gauge wouldn't move or move very slowly after being dead headed like you have done for a test. It has to be the control block, surely?
Each segment of the control block has a spool, in line with this spool, you have two ports to let oil out to either end of the cylinder, in this same line, there will be plugs with load checks behind them or small relief valves. Hopefully the issue is in here....

thanks - so on my machine it has one victor control valve for bucket boom and aux hydrauliucs - the control valve has a pressure relief valve at 2000PSI - which i suspect is the issue but i cannot get a replacement. So i took the pressure relief valve off and it opens and closes as expected but not sure if any other tests i can do - it is difficult to get to the control valve itself without removing lots of pipes which i am afraid are stuck and will get damaged ? So question is how can i test the relief valve in situ any ideas?

 

[Ivan]

thanks - so on my machine it has one victor control valve for bucket boom and aux hydrauliucs - the control valve has a pressure relief valve at 2000PSI - which i suspect is the issue but i cannot get a replacement. So i took the pressure relief valve off and it opens and closes as expected but not sure if any other tests i can do - it is difficult to get to the control valve itself without removing lots of pipes which i am afraid are stuck and will get damaged ? So question is how can i test the relief valve in situ any ideas?

That is not a relief valve. That is the valve that regulates your system pressure. As I told you before get your partys book out ans look to see where the relief vales are in your Hyd system. The part you took out there are 2 types, one that cannot be adjusted which you have and another than can be adjusted, this one will have a screw and a nut that sticks out side the control valve

 

[NHL455]

That is not a relief valve. That is the valve that regulates your system pressure. As I told you before get your partys book out ans look to see where the relief vales are in your Hyd system. The part you took out there are 2 types, one that cannot be adjusted which you have and another than can be adjusted, this one will have a screw and a nut that sticks out side the control valve

i have looked in the manuals and parts book already everywhere and this is the only relief vlve on the control unit - its a 2000PSI fixed cartridge https://www.partspring.com/catalog/product/view/id/174317/s/l455-17784/ the only other relief valve is this one but i think this is on the main drive pumps and this one is 4000PSI and before the main pump https://www.partspring.com/catalog/product/view/id/174362/s/l455-17788/

 

[Tazza]

i have looked in the manuals and parts book already everywhere and this is the only relief vlve on the control unit - its a 2000PSI fixed cartridge https://www.partspring.com/catalog/product/view/id/174317/s/l455-17784/ the only other relief valve is this one but i think this is on the main drive pumps and this one is 4000PSI and before the main pump https://www.partspring.com/catalog/product/view/id/174362/s/l455-17788/

If the spring isn't broken, i'd like to think it's ok. You did say when you dead headed your hydraulic line, your gauge showed 2,000 PSI, that means the relief is working, as when working, it will not allow oil to get over that pressure.

 

[NHL455]

If the spring isn't broken, i'd like to think it's ok. You did say when you dead headed your hydraulic line, your gauge showed 2,000 PSI, that means the relief is working, as when working, it will not allow oil to get over that pressure.

so would thsuggest the main pump?

 

[Tazza]

so would thsuggest the main pump?

You stated you got 2,000 PSI, so i'd think your pump is working. When pumps fail, you get pressure when cold, and as it heats up, it just gets lower and lower.