Why Excavator Hydraulic Systems Fail: The Critical Role of Pressure Relief Valves (And How Used OEM Parts Prevent Catastrophe)

Hydraulics are the lifeblood of your excavator. Without them, your machine is just a heavy paperweight.

And at the heart of the hydraulic system, quietly preventing disaster, sits the pressure relief valve. Ignore it—or install a cheap aftermarket replacement—and you could be staring down thousands of Rands in repairs, downtime, and destroyed components.

This blog explains the critical role of the pressure relief valve, the warning signs of failure, why cheap parts are a disaster waiting to happen, and how Used OEM components from Vikfin save your machine, your schedule, and your bottom line.

1. What a Pressure Relief Valve Really Does

Most operators know the PRV as “that little valve that stops stuff from exploding.” But here’s the truth:

It controls system pressure, protects cylinders, motors, pumps, and lines, and keeps your hydraulic system operating within its safe design limits.

Without it:

• Cylinders overextend

• Pumps overheat and fail

• Motors cavitate

• Hoses blow

• Linkages and pins are overstressed

Think of the PRV as the unsung hero of hydraulic safety. It quietly saves your machine from total destruction hundreds of times per day.

2. How Pressure Relief Valve Failure Destroys Machines

Cheap aftermarket or worn PRVs fail in subtle but devastating ways:

A. Pressure creep

A stuck PRV allows pressure to rise above spec. Consequences:

• Cylinder seals burst

• Pumps are overworked

• Metal filings circulate through the system

B. Early opening

If the valve opens too soon, your system loses pressure:

• Boom lifts sluggishly

• Bucket swings slowly

• Machines lose digging force

• Operators push harder, compounding stress

C. Intermittent failure

A valve that works sometimes and fails others creates unpredictable system behavior:

• Jerky motion

• Oscillating cylinders

• Shock loads transmitted to the boom and arms

• Premature bearing wear

3. The Domino Effect of a Cheap PRV

One tiny valve can wreck an entire hydraulic ecosystem:

• PRV sticks → pressure spikes → pump overheats

• Pump cavitates → metal filings in oil → cylinders scored

• Cylinders leak → boom and dipper stressed → pins and bushings fail

• Secondary contamination → swing motor destroyed → final drive failure

A R1,500 aftermarket valve can trigger R150,000 in repairs. That’s the silent cost of “cheap.”

4. Warning Signs Your PRV Is Failing

Knowing the early signs saves thousands. Watch for:

• Hydraulic oil overheating unusually fast

• Jerky or sluggish cylinder movements

• Unexplained pressure drops or spikes

• Frequent relief valve “clicking”

• Cylinder seals blowing out

• Unexpected machine shutdowns

5. Why Cheap Aftermarket PRVs Are Risky

Aftermarket valves are tempting because of the price. But the risks are enormous:

• Poor metallurgy → valve body warps under pressure

• Weak springs → inconsistent opening pressure

• Loose tolerances → oil bypass and pressure loss

• Inadequate seals → early leaks

• No factory calibration → unpredictable system behavior

The result? Even brand-new aftermarket valves can fail faster than the rest of your machine’s components.

6. How Used OEM PRVs Solve the Problem

Used OEM PRVs from Vikfin are:

• Factory-designed for your specific machine

• Built with correct metallurgy and heat treatment

• Pressure-tested and calibrated

• Free from manufacturing shortcuts

• Compatible with the hydraulic system tolerances

They restore factory-level safety, prevent damage to pumps, motors, and cylinders, and ensure that your excavator performs exactly as it was engineered to.

7. Total Cost Comparison: Cheap PRV vs Used OEM

Component Type	Price	Typical Lifespan	Risk of Failure	Long-Term Cost
Cheap Aftermarket PRV	Low	500–1,000 hours	High	Very High
Used OEM PRV (Vikfin)	Medium	3,000–5,000 hours	Low	Lowest
New OEM PRV	High	6,000–10,000 hours	Very Low	Medium

Even with a slightly higher upfront cost, Used OEM saves tens of thousands in system repairs, downtime, and labour.

8. Real-World Example

A contractor in Gauteng replaced a leaking PRV with a cheap aftermarket model:

• System pressure fluctuated intermittently

• Boom cylinder seals blew after 150 hours

• Pump cavitation caused scoring

• Swing motor picked up contamination

Total downtime + repairs: R120,000Cost of a used OEM PRV from Vikfin: R18,000

Lesson learned: A small part can destroy a machine — or save it.

9. The Rule Every Contractor Should Live By

“The hydraulic system only works as well as its weakest valve.”

Installing cheap PRVs is like gambling with thousands of Rands per day in potential downtime.Investing in Used OEM protects your entire system and keeps your excavator earning money.

10. Why Vikfin Is the Smart Choice

At Vikfin, we:

• Inspect PRVs for wear, cracks, and calibration accuracy

• Test pressure relief under load

• Match the valve to your machine’s hydraulic circuit

• Supply fully tested, OEM-spec replacements at fraction of new-OEM cost

We don’t just sell parts. We protect your machines, your schedule, and your profit margins.

Conclusion

Hydraulic systems are complex. Pressure relief valves may be small, but they are critical to machine survival.

A cheap aftermarket valve is a ticking time bomb.A Used OEM valve from Vikfin is insurance — factory-built, tested, calibrated, and ready to keep your excavator safe, efficient, and productive for thousands of hours.

When it comes to hydraulics: never gamble. Always go OEM.

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