Diagnosis area
Oil, filtration and the system as a whole
Oil condition, water and air, cleanliness, climate and the system-level decisions that follow.
Guides in this area (6)
Each guide lists the checks in the order a workshop should work through them, what each result means, and which parts usually solve it.
Metal particles, dirty oil, short component life
Oil, filtration and the system as a whole
Contamination is the number one cause of repeat failures. Here is what to do after a failure so the new pump is not destroyed by the old…
Oil temperature keeps rising
Oil, filtration and the system as a whole
Over-temperature thins the oil and shortens seal life, so every function weakens.
Foam or milky hydraulic oil
Oil, filtration and the system as a whole
Foam means air, milkiness means water, and both destroy the lubrication film.
Machine slow or noisy when cold
Oil, filtration and the system as a whole
In low ambient temperatures the oil is the problem, not the pump.
Machine weak when it is hot
Oil, filtration and the system as a whole
In high ambient temperatures the hydraulic system runs near its thermal limits.
Repair the pump or replace it
Oil, filtration and the system as a whole
The decision follows measurable evidence, not the age of the machine. Work through these six points and the answer is usually obvious.
The principle behind these symptoms (9)
Reading the mechanism first usually shortens the checklist.
How clean does hydraulic oil need to be? Targets by system type
Technical Guide
Roughly 80% of hydraulic failures start at the oil supply. Here are the particle-size targets by system type, and where contamination…
Test before you believe: what simulation gets right, what it cannot, and why you must test hot
Technical Guide
Models get flow right and pressure wrong - and oil viscosity changes twelve-fold across the working range.
How to Extend the Life of Your Excavator Hydraulic Pump
Technical Guide
Practical maintenance tips: early signs of swash plate wear, proper oil filtration, and recommended replacement intervals for K3V/K5V pumps.
Throttling or displacement control: where hydraulic energy becomes heat
Technical Guide
A valve-controlled system peaks near 38.5% efficiency with a fixed-displacement supply and about 66.7% with load sensing.
Excavator Hydraulic System Maintenance and Care Guide: From Daily Inspection to Fault Diagnosis
Technical Guide
A complete guide to excavator hydraulic system maintenance — from daily inspection to systematic fault diagnosis.
Measure before you replace: reading a valve load flow curve, and why you must test hot
Technical Guide
A worn pump and a worn valve look identical on site. The load flow curve plus two measurements taken hot will tell them apart before you…
Buying a hydraulic unit from abroad: five questions that prevent an expensive mistake
Industry Insight
Nameplate first, pressure class second, rotating group third. Most wrong shipments and early failures come from one of these questions not…
What thirty years of hydraulic industry history means when you buy parts
Industry Insight
Proportional valves and solenoids have been the bottleneck for decades, and the price gap between imported and local parts is a reliability…
Guangzhou Excavator Parts Market: A Decade of Change, Current Status, and Future Potential
Industry Insight
Guangzhou has grown from the world's largest excavator parts wholesale hub into an export-driven, digitally transforming industrial nexus.
Units we supply for this topic (5)
Catalogue-verified units whose internals are the ones described above.
K5V140DTP
27–33 t hydraulic excavator
140 mL/r (per pump) · 34.3 MPa
K3V180S
industrial open circuits
180 mL/r · 34.3 MPa
K3V280SH
large open-circuit equipment
280 mL/r · 34.3 MPa
K7V125
harsher working environments, open circuits
125 mL/r (max. 130) · 35 MPa
FTD26
13–16 t excavator / drilling rig / crawler crane
Parts that solve this (6)
Catalogue part lines from the same families. Search the full library by part number from the parts library.
2943800424
SET PLATE · pos. 153
2943800488
SET PLATE · pos. 153
29241100-056
SET PLATE · pos. 153
2924110-0049
SET PLATE · pos. 153
2924110-0009
SET PLATE · pos. 153
OORBG35W
O-RING · pos. 702
Machines this applies to (6)
Machine pages that list the units above as fitment, model by model. See every machine →
SANY SY335
Machine page
Pump, swing motor and travel assembly options for this machine, with the fitment list.
SANY SY365
Machine page
Pump, swing motor and travel assembly options for this machine, with the fitment list.
VOLVO EC300D
Machine page
Pump, swing motor and travel assembly options for this machine, with the fitment list.
DOOSAN DH300-9
Machine page
Pump, swing motor and travel assembly options for this machine, with the fitment list.
KOMATSU PC300-8
Machine page
Pump, swing motor and travel assembly options for this machine, with the fitment list.
HYUNDAI R300-9
Machine page
Pump, swing motor and travel assembly options for this machine, with the fitment list.
Other diagnosis areas
Pump and pressure supply
Pressure, delivery, wear and the pump-engine match: the guides that start at the source of the oil.
Swing, travel and drive assemblies
Motor and reduction-gear complaints: slow swing, weak travel, run-away, noise and metal in the gear oil.
Boom, arm and cylinder functions
The working functions: drift, creep, jerky movement and every-function-at-once complaints.
Valve and pilot control
Spools, pilot pressure, proportional solenoids and pressure transients: the control layer between lever and load.