Volvo EW180C hydraulics

[pados1002]

Hi guys, I recently had my pump and main control valve serviced. MCV had a damaged bucket spool from debris and was honed and rechromed to spec. In general after I bought the excavator last year, I noticed that it had neither the speed nor the hydraulic power that it should have.
Anyway, now after rebuilding everything I m trying to figure out why I still lack power on my functions.
According to machine's sensors when I pushing the excavator I achieve about 310+ bar.
Tried to to measure the Δp pressure(Pump pressure minus LS pressure). Removed LS plug from pump solenoid. I took measurement on the LS pressure from the proper nipple according to the service manual and I saw 22 bar in idle and pressure rising accordingly when I m using functions. So I guess it 's normal.
What i can't measure, is the pump pressure, because after I m starting the engine, the pump starts building pressure up to 100bar for 4-5 sec and then the manometer goes to zero. The moment the pressure drops I think I m hearing something like a click from the excavator, but I cannot say for sure what it is.
However with the LS plug removed, the excavator goes crazy. Full aggressive, speed and power to the point engine stalls if I pull the levers all the way.
What do you think is wrong guys? Thanks in advance!

 

[pados1002]

@jazztalk12 thank you for the reply mate! LS line from MCV to pump was checked and looks fine to me. Around 32 bar difference from the main pressure. I also disassembled the pump regulator and cleaned everything very carefully. I didn't notice any dirt or something like that. It 's a really annoying situation.

 

[V8Druid]

@jazztalk12 thank you for the reply mate! LS line from MCV to pump was checked and looks fine to me. Around 32 bar difference from the main pressure. I also disassembled the pump regulator and cleaned everything very carefully. I didn't notice any dirt or something like that. It 's a really annoying situation.

LS line feed from the MCV usually connects to a tiny throttled orifice (circa 0.6mm) and is easily blocked (don't bother asking how I know .. the rubber crumb took a lot of finding)

0.6mm throttle orifice assembly from MCV block

it's 9 years since I had this apart but sounds a similar issue .. your delta pressure sounds about right at idle though, from memory - this was on my M1500 Hydrema duck and occurred suddenly, mid operation and was like dropping into 'limp, limp mode '

 

[pados1002]

@V8Druid I m pretty sure I ve heard about similar cases again. To tell the truth I think I found the orifice but I didn't know how to remove it from the body so I cleaned everything with compressed air and break cleaner as it was. I removed everything else besides this orifice. I really hope this is my issue.

 

[V8Druid]

@V8Druid I m pretty sure I ve heard about similar cases again. To tell the truth I think I found the orifice but I didn't know how to remove it from the body so I cleaned everything with compressed air and break cleaner as it was. I removed everything else besides this orifice. I really hope this is my issue.

if you've a 'crumb' MCV side of the orifice throttle it'll need to come out of the MCV ... mine was like an extended M/F union which I screwed out of the MCV body and stripped on the bench - the centre 'bobbin' with two minute slots in the conical seats, forming the restriction size, seats on two removable hardened conical seats, screwed into the body with an Allen key - took 'em out and washed everything, found the rubber crumb MCV side of the restrictor - blew it all dry and re-assembled.
blew the LS line out too with 150psi into a collection bottle (looking for detritus) and put it all back together -- touch wood - been faultless since

 

[pados1002]

Guys I 'm back with I think good news. First of all, I had to pull out the pump again, sent it in a different hydraulics shop and what they found was not that good. Apparently the first shop opened the pump, replaced only the bearings and closed it back. But there was more to do for sure. Anyway pump returned, there was a slight improvement but bucket and dipper still the same, more or less. Finally today we had a Volvo service crew at the excavator and what they told us was that the 2-piece boom excavators, at least in Volvo and also in Komatsu, have the reliefs really low to prevent damages at the boom pin and cylinder.
With my consent, they raised main relief pressure valve on the MCV to about 350bar from the 310 that was before. And boom, a completely different machine. Bucket and dipper woke up finally. I know that this raise in pressure has it 's risks but now I finally happy with how it works!

 

[V8Druid]

Guys I 'm back with I think good news. First of all, I had to pull out the pump again, sent it in a different hydraulics shop and what they found was not that good. Apparently the first shop opened the pump, replaced only the bearings and closed it back. But there was more to do for sure. Anyway pump returned, there was a slight improvement but bucket and dipper still the same, more or less. Finally today we had a Volvo service crew at the excavator and what they told us was that the 2-piece boom excavators, at least in Volvo and also in Komatsu, have the reliefs really low to prevent damages at the boom pin and cylinder.
With my consent, they raised main relief pressure valve on the MCV to about 350bar from the 310 that was before. And boom, a completely different machine. Bucket and dipper woke up finally. I know that this raise in pressure has it 's risks but now I finally happy with how it works!

can understand that but can't see why you had to up the pressure to get things 'cooking' ????

 

[pados1002]

can understand that but can't see why you had to up the pressure to get things 'cooking' ????

Honestly I don't know! I 'm not sure however how exactly the one piece boom ew works. If it's working in higher relief pressure or not. However weather is still relatively cool, so I guess I have to wait until temperature rises, so I have a better understanding of oil temperature. If it stays in acceptable temps, then I guess I will have to worry only for exploding aged hoses