Komatsu PC55MR-2- Slow Hydraulics

[IslandPC50MR]

Hello all, I am having trouble with my Komatsu PC55MR-2 excavator. After using a breaker attachment for the first time, all the hydraulics (boom, bucket, travel, blade etc.) started to operate slow. I have replaced all the hydraulic filters and bled the components as instructed in the manual, but the symptoms remain the same. The slow movement does goes away only after the arm or blade is lifted and lowered 3 to 4 times, then all the hydraulics return to normal speed; after a few minutes of operation, the hydraulics slow again. I have tested all the pressures from the hydraulic pump (boom, bucket, travel, blade etc.) except for the LS Differential Pressure, and all are within spec. Would the gear-pump relief valve cause this problem?, I have searched and have not seen this problem anywhere. Thanks for your input.

 

[Marcrus]

Check servo valve inlet pressure, pump swash plate probably stuck, the ball the swash plate pivots on gauls up and jams the plate

 

[Kobe Steel]

Check servo valve inlet pressure, pump swash plate probably stuck, the ball the swash plate pivots on gauls up and jams the plate

As mentioned by Marcrus this is a common issue that usually starts to occur around the 4000 to 5000 hour meter mark.

 

[IslandPC50MR]

Thanks for the replies; I will check that this week.

 

[IslandPC50MR]

I attempted to test the LS pressure, but I have all the test fittings except the one needed for the LS pressure test... Komatsu flat faced O-ring metric fittings?? Seems to be close to 14Mx1.5 for the female end but not for the male end. There is an 14Mx1.5 adaptor that extends the hose, but the test fitting will not screw on. BSPP, Metric, Metric ORF...too much going on for this machine.

 

[Marcrus]

It should be m10*1.25 test fitting

 

[IslandPC50MR]

Thanks for the input; the ends are M14x1.5, but the t-fitting adaptors for the gauge will not screw on with the deep inset. I purchased a "Stainless Steel M14 x 1.5 Female to M14 1.5 Male with 1/8 NPT Port Oil Pressure Sensor Adapter Tee Adding an Oil Pressure Gauge or Turbo Supply line" hoping this will work, as the pressure should be low enough to not be a problem...right?

 

[Marcrus]

Why not just go off the hose connection to the right angle part? I think it's just -8 or -10 orfs then and orfs tee adaptors are fairly common to get rather than deal with oring boss, your fitting may work, but it is full system pressure in there as well just be out of line of fire

 

[IslandPC50MR]

Great suggestion; the ends maybe metric as per the quote below. I could not find a set of metric ORFS t-fitting for the hose ends and the Komatsu OEM part for sale in AUD is $500. I will take it to the hydraulic hose store(s) and have them verify 100% for the hose fittings. I am in a remote country... they don't even have BSP zerk/grease fittings here and lead time for parts is 2 weeks or more.

"Komatsu flat face fittings is metric o-ring face seal fittings, metric orfs fittings is different from british flat face adapter and SAE UNF thread orfs adapter."

 

[Marcrus]

Yeah nah U can get a kit on eBay for like 200$ AUD with every orfs fitting you'd ever need, U in Aus ?

 

[IslandPC50MR]

I am in the West Indies, South of USA.