The 10 Excavator Parts Most Likely to Stop Your Machine From Working
- RALPH COPE
- 3 hours ago
- 9 min read
An excavator doesn't have to be completely broken to be completely useless.
One failed component can bring a 20-tonne machine worth hundreds of thousands — or even millions — of rand to a grinding halt.
The frustrating part is that the component causing the problem may be relatively small.
A failed sensor.
A damaged hydraulic hose.
A leaking cylinder.
A faulty valve bank.
A failed final drive.
The machine doesn't care how much the rest of it is worth.
If one critical component isn't doing its job, the excavator isn't digging.
And when an excavator isn't digging, it isn't making money.
At Vikfin, we deal with excavator components every day. We see which parts fail, which parts are expensive, which parts are difficult to source and — perhaps most importantly — which parts can often be repaired or replaced without replacing the entire machine.
So, if you own or operate a 20- or 30-tonne excavator, here are 10 components that can bring your machine to a standstill — and what you can do about them.
1. Final Drives
Let's start with one of the big ones.
The final drives transfer power from the hydraulic motors to the tracks.
When one fails, your excavator may:
Struggle to move.
Move slower in one direction.
Pull to one side.
Make grinding or unusual noises.
Leak hydraulic oil.
Lose all drive on one side.
And eventually:
It stops moving.
A final drive failure can be an expensive problem if you immediately go to the OEM for a brand-new replacement.
But there are alternatives.
Depending on the machine and condition, you may be able to:
Repair the existing unit.
Rebuild it.
Buy a refurbished OEM unit.
Buy a good used OEM unit.
Consider a quality aftermarket replacement.
The important thing is not to assume that a failed final drive means your excavator is finished.
It doesn't.
2. Hydraulic Pumps
If the final drives move the machine, the hydraulic pump is effectively responsible for providing the muscle that makes the rest of the excavator work.
A hydraulic pump problem can result in:
Slow movements.
Weak digging power.
Poor response.
Excessive heat.
Abnormal noise.
Loss of hydraulic pressure.
Complete loss of hydraulic function.
And because excavators depend so heavily on hydraulics, a serious pump failure can
effectively turn the machine into a very expensive paperweight.
Hydraulic pumps can sometimes be repaired or rebuilt.
Depending on the failure, however, replacement may make more economic sense.
Again, don't automatically assume:
“New OEM pump.”
Investigate all your options.
3. Valve Banks
The valve bank is another component that most excavator owners don't think much about until something goes wrong.
It controls the distribution of hydraulic oil to the various functions of the machine.
If something goes wrong with the valve bank, you may experience:
Certain functions not working.
Slow or erratic movements.
Functions working intermittently.
Hydraulic overheating.
Poor machine performance.
Unusual hydraulic behaviour.
The difficulty is that valve-bank problems can sometimes be complicated to diagnose.
Is the problem actually the valve bank?
Or is it the pump?
Or a control issue?
Or a blockage?
Or an electrical problem?
This is why proper diagnosis is critical.
A valve bank isn't something you want to replace simply because someone guessed that it was the problem.
But when it does fail, finding a replacement quickly can make an enormous difference.
4. Hydraulic Cylinders
The boom.
The dipper.
The bucket.
These are the components that give an excavator its physical movement.
And hydraulic cylinders operate under enormous forces.
Common problems include:
Damaged chrome rods.
Bent rods.
Pitted rods.
Worn seals.
Internal leakage.
Damaged bushes.
Barrel damage.
Mounting-point wear.
The good news?
Hydraulic cylinders are often repairable.
A cylinder that is leaking doesn't necessarily need to be replaced.
Depending on its condition, it may be possible to:
Replace the seals.
Repair the rod.
Re-chrome the rod.
Replace bushes.
Repair the barrel.
Restore the mounting points.
This is one area where refurbishment can provide tremendous value.
5. Engines
There isn't much point having a perfect hydraulic system if the engine won't run.
Engine failure is obviously one of the more serious excavator problems.
Signs of trouble can include:
Excessive smoke.
Blow-by.
Loss of power.
Excessive oil consumption.
Overheating.
Low oil pressure.
Coolant contamination.
Knocking or unusual noises.
Difficulty starting.
The important question is:
Does the engine need rebuilding, repairing or replacing?
Sometimes a rebuild makes sense.
Sometimes a replacement engine is more economical.
And sometimes a good used OEM engine is the obvious answer.
For an older excavator, a used engine can potentially transform the economics of the repair.
Instead of spending an enormous amount rebuilding a tired engine, you may be able to install a known-good replacement and get the machine back to work much faster.
6. Cooling Systems
This is one of the most underestimated causes of excavator downtime.
An excavator's cooling system can include:
Radiator
Oil cooler
Intercooler
Fan
Fan motor
Hoses
Associated components
When cooling performance deteriorates, the consequences can be serious.
The machine may start overheating.
Hydraulic oil temperatures may rise.
Engine performance may deteriorate.
And continued overheating can eventually cause much more serious damage.
A blocked radiator may be relatively easy to deal with.
A damaged cooling pack may require replacement.
The important lesson is:
Don't ignore overheating.
An overheating excavator isn't simply an inconvenience.
It is a warning.
7. Wiring Harnesses
Here's one that can drive a mechanic completely insane.
The wiring harness.
A hydraulic component can be perfectly healthy.
A mechanical component can be perfectly healthy.
But if the electrical signal isn't getting where it needs to go, the machine may refuse to cooperate.
Electrical problems can cause:
Intermittent faults.
Sensors not functioning.
Warning lights.
Starting problems.
Hydraulic functions not operating.
Communication errors.
Engine management problems.
And because wiring harnesses can be damaged by:
Heat
Vibration
Oil
Water
Rodents
Previous repairs
Age
they can become increasingly problematic as machines get older.
Sometimes the solution is repair.
Sometimes it's replacement.
And sometimes finding the correct used OEM harness is considerably easier than trying to diagnose and repair years of electrical damage.
8. Slew Motors and Slew Components
An excavator that can move forward and backward but can't rotate isn't particularly useful.
The slew system allows the upper structure to rotate relative to the undercarriage.
Problems can manifest as:
Slow slew speed.
Loss of power.
Abnormal noise.
Jerky rotation.
Excessive movement.
Oil leakage.
The slew motor itself can sometimes be repaired or rebuilt.
But again, a good used OEM component may offer an attractive alternative.
And when you're dealing with an older machine, this can make a major difference to the economics.
9. Undercarriage Components
The undercarriage is one of the hardest-working parts of an excavator.
It takes punishment every day.
And eventually, it wears out.
The major components include:
Track chains
Track shoes
Rollers
Idlers
Sprockets
Track adjusters
A worn undercarriage can result in:
Poor machine stability.
Excessive track movement.
Increased wear.
Reduced efficiency.
Higher risk of component failure.
The challenge is that replacing the entire undercarriage can be extremely expensive.
That's why it is important to assess the individual components.
Sometimes you don't need to replace everything.
And sometimes a good used component can extend the life of the machine at a fraction of the cost of a complete new undercarriage.
10. Swing Bearing
And finally, one of the biggest — and potentially most expensive — mechanical components on the excavator.
The swing bearing allows the upper structure to rotate relative to the undercarriage.
Over time, it can develop:
Excessive play.
Wear.
Noise.
Damage to the race.
Lubrication problems.
A worn swing bearing can be a major repair.
And because it sits at the centre of the machine, replacement can be a significant job.
Again, early detection matters.
If you catch excessive wear before it causes additional damage, you have more options.
If you ignore it until the bearing is severely damaged, the repair can become much more expensive.
The Important Thing About All 10 Components
There's a common thread running through all of these failures.
The component doesn't necessarily need to be replaced with a brand-new OEM part.
There may be several options.
For example:
Component | Repair | Refurbished OEM | Used OEM | Aftermarket | New OEM |
Final drive | ✓ | ✓ | ✓ | ✓ | ✓ |
Hydraulic pump | ✓ | ✓ | ✓ | ✓ | ✓ |
Valve bank | ✓ | ✓ | ✓ | ✓ | ✓ |
Hydraulic cylinder | ✓ | ✓ | ✓ | ✓ | ✓ |
Engine | ✓ | ✓ | ✓ | ✓ | ✓ |
Cooling pack | ✓ | ✓ | ✓ | ✓ | ✓ |
Wiring harness | ✓ | — | ✓ | ✓ | ✓ |
Slew motor | ✓ | ✓ | ✓ | ✓ | ✓ |
Undercarriage | ✓ | — | ✓ | ✓ | ✓ |
Swing bearing | ✓ | ✓ | ✓ | ✓ | ✓ |
The exact options depend on the machine and component.
But the point is simple:
Don't accept the first solution you are given.
The Most Expensive Part Is Often Downtime
Let's imagine your excavator earns R6,000 per day.
A major component fails.
The component itself costs R100,000.
You might think:
“That's the cost of the breakdown.”
It isn't.
Suppose the part takes three weeks to source.
You've now lost around 15 working days.
That's another:
R90,000 in lost revenue.
Your R100,000 component has effectively become a R190,000 problem.
And that is before labour, transport and other costs.
This is why availability matters almost as much as price.
The Case for Used OEM Parts
This is where the used OEM market becomes particularly valuable.
Suppose a 20-tonne excavator needs a final drive.
You have three choices:
New OEM: R250,000
Aftermarket: R140,000
Good used OEM: R80,000
If the used OEM component is properly inspected and has plenty of useful life remaining, it may be the obvious economic choice.
You have saved:
R170,000 compared with new OEM.
That is money that can remain in your business.
And if it gets the machine working quickly, you've potentially saved even more in avoided downtime.
But Don't Buy Used Parts Blindly
This is extremely important.
The used parts market is not simply:
“Find the cheapest part on the internet.”
You need to know what you're buying.
Ask your supplier:
What machine did it come from?
What was the condition of the donor machine?
Has the component been inspected?
Has it been tested?
Has it been refurbished?
What exactly has been done to it?
Is there a warranty?
Does it definitely fit my machine?
A cheap part that doesn't work is not cheap.
It's expensive.
Know Your Machine Before It Breaks
The best time to think about excavator parts isn't necessarily when your excavator is already sitting broken.
If you're operating older equipment, it's worth knowing:
What major components are fitted.
Which components are difficult to source.
Which parts are commonly available used.
Which parts can be refurbished.
Which components are interchangeable.
What your critical spare-parts risks are.
This is especially important for businesses running multiple machines.
If you have ten identical 20-tonne excavators, for example, your parts strategy can become significantly more efficient.
One donor machine can potentially supply components for several machines.
Prevention Is Still Better Than Replacement
Of course, the best component failure is the one that never happens.
Regular maintenance matters.
Monitor:
Hydraulic oil.
Engine oil.
Coolant.
Track tension.
Hydraulic leaks.
Abnormal noises.
Operating temperatures.
Cylinder condition.
Final-drive leaks.
Slew performance.
And perhaps most importantly:
Pay attention to changes.
An excavator usually gives you warning signs before a catastrophic failure.
The operator who notices that the machine is becoming slower, hotter, noisier or weaker has an enormous advantage over the operator who simply keeps working until something explodes.
The Bigger Vikfin Philosophy
At Vikfin, we don't see an excavator as a machine that either works or doesn't work.
We see it as a collection of components.
If one component fails, that doesn't mean the machine has failed.
It means:
One component has failed.
That sounds obvious.
But it changes the economics completely.
A R1 million excavator doesn't necessarily need a R1 million replacement.
It may need a R50,000 component.
Or a R100,000 component.
Or a refurbished component.
Or a component from another machine.
The challenge is finding it.
That's What We Do
Vikfin buys used excavators and dismantles them for components.
We specialise particularly in components for 20-tonne and 30-tonne excavators, including many of the machines commonly found in South Africa.
We deal in components such as:
Engines
Final drives
Slew motors
Valve banks
Hydraulic cylinders
Radiators
Intercoolers
Oil coolers
Wiring harnesses
Tracks
Buckets
Quick couplers
Counterweights
Exhaust systems
Bonnet panels
And much more
The objective isn't to sell you something you don't need.
It's to find the component that gets your machine back to work.
Don't Let One Failed Part Kill a Good Excavator
An excavator can be mechanically sound and still be stopped by one failed component.
That doesn't necessarily mean you need to replace the machine.
It doesn't necessarily mean you need to buy a brand-new OEM component.
And it certainly doesn't mean the machine is finished.
There are often several ways to solve the problem.
Repair it.
Refurbish it.
Find a good used OEM replacement.
Consider aftermarket.
Buy new OEM if that's the right economic decision.
The trick is knowing which option makes sense.
And when your excavator is sitting idle, speed matters.
Because the longer your machine stands still, the more expensive that broken component becomes.
So the next time something goes wrong, don't just ask:
“How much is the part?”
Ask:
“How quickly can I get the machine working again — and what is the most economical way to do it?”
That's the question that matters.
And that's where Vikfin comes in.
Vikfin — Flexible. Fast. Friendly. Affordable.
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