VOLVO EW180C issues after pumps and MCV service and rebuild

[pados1002]

Hey guys, finally after a year we bought the machine and since the first moment we realized issues with MCV bucket spool we sent pumps and MCV for repair. Main Pump was in good condition and bearings were replaced. MCV got the bucket spool repaired and chroming and the body was slightly honed because of a rough edge after debris got into the system.
Parts returned and fitted back to the machine. However I didn't see a great improvement. Bucket is faster now but overall I think the excavator is looking more lazy than before.
According to the machine shop and the excavator sensor the max pressure is 310+ bar (I think we'll inside the specs) but what I noticed is that the engine 's load is not that big when the excavator is working hard. What could I adjust in order to make it better?

 

[nikthewho]

your work points most strongly to issues in the control side of the pump, rather than a simple low‑relief‑pressure problem.

• Check Load‑sensing (LS) signal: crushed, incorrectly connected, leaking, or partially blocked LS line between MCV and pump controller, or incorrect LS margin setting.
• Pump control mis‑adjustment: maximum displacement stop, power‑control (torque limit) setting, or LS standby/margin pressure set too low.
• Calibration / work‑mode issues: electronic proportional control (if fitted) or power‑mode settings limiting commanded pump flow.
• Residual internal leakage in the MCV, especially if honing created excess spool‑to‑bore clearance in more than just the bucket section.

Install main and LS pressure gauges and repeat tests on boom up, stick in, and bucket curl, both single and combined. Adjust LS margin/standby pressure to spec if it is low. If pressure is fine but performance is still poor and engine load is light, carefully increase pump maximum displacement or slightly relax torque‑limit (within Volvo’s specified range), re‑testing after each small change. If performance remains poor or oil runs hot, investigate MCV leakage and consider re‑bench‑testing both pump and valve on a test stand.

 

[pados1002]

@nikthewho thank you so much for replying! I m reading the hydraulics manual the past 2 days. I m trying to understand the system and how it works. I think i m figuring out but there 's this point, the torque limit that I can't find anywhere. I m trying to understand what it is and how to check and adjust it, but nothing in the manual refers to that. Any idea?

 

[Ben Witter]

First I would check and record cycle times for all functions and compare to the service manual specs. What you perceive to be slow may in fact be fine. Standby pressure will affect all speeds if too low and if too high can make it jerky or uncontrollable. You can check standby pressure at high idle and then check DeltaP with machine elevated and in travel mode with the wheels turning

The control pressure should only come into play when engine load is severe enough to drop rpm's to the point of a possible stall. You can check that pressure to make sure it is not increased at no load conditions

 

[pados1002]

@Ben Witter really appreciate your reply brother! Any advice will be super helpful. I 'm waiting for a kit of gauges, so I can take my measurements. I 'm pretty sure that not a single one of the functions, or even the combination of them is able to put the engine in stall. I think the max rpm drop that I 've seen is 150-200rpm. However I think I will reply here again soon!

 

[pados1002]

Today after a few hours at work I noticed a few more issues. First of all the travel mode is way worse than before. The machine would not even flinch in "rabbit" and uphill. Today I had to go to "turtle" so I could finish the same route. Boom before the pump and MCV service was the only really reliable function. Today when the bucket was filled with muddy soil, boom was struggling. I really hope it will be, just a screw adjustment and not rabbit hole.

 

[pados1002]

Today I received my kit of pressure gauges and tried to take measurements. What I noticed when I tried to measure LS pressure is that it idles at 22 bar and when I put the machine in travel or work and use functions it will rise accordingly and I guess it is ok. The issue is with the main pressure. After starting the engine for 4-5 seconds I saw the pressure rising up to 100bar and then suddenly the gauge falls to zero. When this happens I think I hear something like a click from either the pump or the MCV. I can't say for sure. Either in idle or travel/work it won't give me measurements until I turn the engine off and after sometime I restart. However when I unplugged the LS solenoid plug from the pump the excavator went crazy. Super aggressive and powerful to the point the engine stalled. Obviously its not possible to work like that. So any ideas?

 

[pados1002]

A week later, I tried different things and I still can't find the issues. What I did so far is to measure main pump pressure, LS pressure.
Main pressure 310+ on deadend functions with LS about 32bar less under load. So my Δp around 10+ bar more than what Volvo gives in manual(22+1 in service manual). I tried to use the excavator with this LS unplugged. If I go aggressively on joysticks the engine will stall. If I go really easy and for example the arm finds load in digging, then it can overcome the stall even I pull the lever fully. But again I don't have hydraulic power. I even tried clockwise the Δp bolt. It made the engine to try harder but again when it finds load no power and "jet engine" sound from the pump. I even removed the Ls regulator to clean the spools. Didn't find dirt inside. I 'm really desperate guys at this point. If potential solutions come to your mind please let me know and I will try everything.