Hi, I have a 2012 Caterpillar 930K. Everything was working and operating fine on the machine and then one day there was a pretty bad drip coming from the implement valve under the front hydraulics. We removed the implement valve and fully resealed everything, now the implement valve still leaks slightly so we think it’s in the o rings that sandwich them together. Our other issue is now we have only 300 psi of pump pressure. The loader arms will not go up, quick coupler will not work. The only functions that work is turning, forward and reverse and curl. We are thinking that the leaking implement valve caused damage to the implement pump. Any ideas would be greatly appreciated.
If everything worked fine, albeit with a hydraulic oil leak, before the implement valve was disassembled then my bet would be that somehow the valve was reassembled incorrectly. Were Cat OEM seals used in the repair.? What exactly was replaced.? Please supply a machine Serial Number. Also do you have any Active Diagnostic Codes.?
We thought the same thing but the main pressure line before it reaches the implement valve is 300 psi. Just every o ring was replaced. They were not oem seals, there are no active diagnostic codes. The serial number is RHN00768
That's one thing that worries me. Second is the possibility of incorrect re-assembly. if the system was working before then it should work now if the valve was OK. Attached are the parts breakdown and disassembly/assembly instructions for the implement control valve which may help.
Thank you, I will let you know when we dissemble it. Even if the implement valve was reassembled incorrectly, What is your thought on why the main line pressure going into the implement valve is only 300 psi? We did not touch anything besides the valve so it does not make sense on why coming from the main pumps there is little to no pressure
Look at Item ref #1 in the first illustration of the parts listing. It is a "Manifold & Relief Valve" . Could a piece of shrapnel from somewhere be lodged in it.? If oil is leaking past that valve then the pump will never produce pressure.
Yes, it could be, it is still leaking from in between one of those so we are going to pull it back apart and see what’s going on. Looking at the valve installed in the machine it is leaking from somewhere under the valve when it’s installed
Its been a couple of months of the valve being rebuilt at a hydraulic place. I picked up and brought them all oem seals and o rings from the dealer. We just installed the valve and now no more leaking but the loader arms will still not go up and quick attach will not work.. same problem as before. It feels there is no pressure from the implement pump. Im going to plug into the machine tomorrow. What should I look for towards the implement pump side?
Attached a series of five tests you can do. I would suggest that you don't try to adjust anything, simply measure pressures and report back. Reading back through this thread from the beginning I still cannot get it out of my head that the system worked fine until a leaking control valve was removed for resealing then it never worked again afterwards. To me that screams incorrect assembly of the valve when it was resealed the first time or the possibility of some hydraulic lines being swapped when they were reconnected. I agree there is always a possibility that the pump has taken a dump but I don't pin all my faith on conincidencs. YMMV.
Thank you for this. The first test we have right around 300 psi from the implement valve. We put a pressure tester on the implement pump control valve and we have 0 psi, both at idle and trying to move the loader arms up and down.
Also our implement pump pressure on Cat ET still says 315 psi
When you try to move the implements does the 315psi in ET change at all.? It sounds as though the implement pump staying in low pressure standby mode and is not getting a command to upstroke.
It stays around 315 at idle. When you raise the idle and try to move the boom up it barely goes above 325 psi
That appears to confirm that the pump is sitting at low pressure standby and is not upstroking. Attached the hydraulic schematic in case it is of any help to you.
Do you think we should pull the pump and get it rebuilt or can it be something on the pump causing it?
From the hydraulic schematic I posted above the signal to upstroke the pump comes from the implement control valve to the pump (dashed purple line) and there is a test point on the pump marked "P4". It would be interesting to have a gauge on that test point, operate the implement controls ans see what happens. If you click on the P4 it will take you to an illustration showing the location on the machine. With the signal to upstroke the pump coming from the implement control valve it brings me back to my earlier question of "what went wrong the first time the valve was re-sealed, because after that the implements never worked again.?". I still have money riding on the possibility that either the valve was rebuilt incorrectly the first time it was torn down or that hoses were incorrectly hooked up at the same time.
Is this where the P4 is? Because that reads 0 psi
All of the lines were just long enough so I’m not sure if they were connected wrong. At the same time I’m now the 3rd person that reinstalled it
If I click on P4 of the hydraulic schemtic it takes me to this illustration on Page 24 which may or may not be the test point in your photo. Only you can tell that.
Yes correct that is the test fitting where I put the gauge and it said 0psi, doing functions and at idle and high idle
This sure sounds like a resolver problem Try holding curl and trying the other functions
Curl works, loader arms up and down do not work. Aux hydraulics and quick attach does not work
while you are holding the curl in???
By any chance are there any markings on the ports where the smaller diameter hoses hook up to the control valve.? Hopefully one of them might be marked "LS" (load sense). The same hose that connects to that port on the control valve is the one that should connect to the valve (arrowed) on top of the implement hydraulic pump that your test connection is hooked to in the other photo. Can you find a Part Number sticker on that hose anywhere.?
Scratch all the above. If the curl function is working then the pump is upstroking when that particular control is operated. What pressure do you measure at that test point when the curl function is activated.? As per the question asked by @pittsburgh cat man - what happens if you hold the curl lever and then try to operate either the lift or the 3rd function.?
When curl is activated it’s still 0 psi. When I hold the curl and try the lift and or aux hydraulic it still does not do anything
Just confirmed. Yes while holding curl, no other function works
That line goes to this point on the block. It has a smaller fitting size than the rest so I’m pretty sure it’s on the correct spot
This is what that line says
dead engine boom lower valve isn't open is it?
How would I figure that out?
If you have a operators manual It should tell you how to lower boom with dead engine from schematic the part number of it is 1121817
Here's the part of the operator manual regarding the lowering valve.
I just tried it and it’s not that. I’m starting to think it’s the pilot gear pump. The valve has been leaking for a while now so maybe with all these problems it finally ran dry or something and blew out. Both test ports on the implement valve are 300 psi ish so I was looking the rear one is for pilot and that reads 300 psi. Is that pressure not high enough to for the LS line to get pressure? I pulled the LS line from the implement block and no pressure at all comes out of it
With the engine running and an implement control (Lift or Aux) moved.? Did you double check that the hose coming from the LS port on the control valve is connected to that valve on top of the implement pump via the 366-2737 Hose.?
Yes with the engine running it flows but maybe at 2 psi no pressure or anything. Also yes the hydraulic line 366-2737 goes from the LS port on the valve to the top of the implement pump. I do not have any help near me to try moving the lift or aux to see what happens but I do have the pressure gauge on the test port on the top of the implement pump and when I do that it still reads 0 psi
Should I make a test line from the test port since it’s 300 psi and connect it to the LS port to see if the functions work?
I think I would pull end cap on lift valve and coupler valve and see if the spools will move it might be a little messy though
I just pulled the cap on the spool valve for the lift and it did not do anything. That would be #28 and the center cap in my other picture
The caps on the bottom of the last picture could you move the spools??
I didn’t try. Should I try to manually move them and see if the boom goes up?
No do not try that it could get really ugly All I'm interested in is if the spools will move with the engine off with your fingers I'm asking because a lot of the valve banks have tiny shims that go on the stack bolts between each valve section missing shims could possible distort valve body and stick the spool
What’s with the freshly painted valve body? Was it recently serviced?
Yes the second hydraulic place that I brought the valve to completely rebuilt it and resealed it. After getting it back from the first hydraulic place it was still leaking.
So there is every chance that the first place could have rebuilt it wrong and the second place tore it down and rebuilt it to fix the leak not knowing it may have been assembled wrong.? Was the second place even told when it was shipped to them that it might have been wrongly assembled.? That’s why a few posts back I included a full parts breakdown of the entire valve and every individual section in it, so that someone could check the assembly was correct as they pulled it apart.
Yes I have a call into them now. I brought them all the paperwork you sent over when they rebuilt it so they can go through everything. I am hoping they bench tested everything
Above is how your first post started. Forgive me for going back to this again but I think it is important that those people who have recently joined into the thread trying to help you solve this issue read this and confirm my suspicions or come up with alternative suggestions. So in summary:- 1. The machine hydraulics were working correctly but there was a bad drip from the main control valve. 2. The valve was removed and "resealed". (Only later did the information come out that this work was done by an outside shop.) 3. When the valve was reinstalled there was still a slight leak from between some sections. However the big problem was that neither the bucket lift nor the Aux functions worked. So if the valve was correctly operating all 3 functions OK (albeit leaking) when it was sent to the first outside shop and wasn't working when it came back - draw your own conclusions.
Yes Nige, exactly why I asked about the paint. When you fix things for a living, part of the job is being a bit of a detective, trying to piece together the whole story.
I am still waiting to hear back from the hydraulic repair place. I am able to freely move the spool for the lift on the implement block. What I do know is that no pressure comes out of the LS Line