Generator brands · Complete sets and engines
Cat Generator Set Repairs, Servicing and Maintenance
We repair, service and maintain Caterpillar (Cat) generator sets on site across Gauteng, from commercial standby sets to the large prime-power sets that run mines and plants. A Cat set combines a Cat engine, usually an EMCP controller, and an alternator matched to its rating, and we work on all three, along with the fuel, cooling and changeover systems. Tell us whether your set is used for standby or prime power: it changes how it should be maintained.
Established 2006
20 years of experience
24/7 operations
We Arrive Within 1–2 Hours
(usually within 1 hour)
Free callouts and quotations
One-year warranty
Qualified and certified technicians
We Service & Repair All Generator Brands
All generator makes and models
1 kVA–20,000 kVA capability
Where Cat sets earn their keep
Cat sets are chosen where the generator is critical: mines, processing plants, hospitals, data centres and large commercial buildings. Many run as prime power, carrying a site for long hours, and paralleled sets share a load between several machines. Office parks and shopping centres that ran Cat standby sets through years of load shedding have also put far more hours on them than their original maintenance plans expected.
Caterpillar also owns Perkins and FG Wilson. Some smaller Cat engines share their design with Perkins engines, but parts are never assumed to cross over: they are ordered by the Cat engine’s own serial number.
Standby, prime and continuous: what the rating means for upkeep
| Rating | How the set runs | What it changes for maintenance |
|---|---|---|
| Standby | How the set runsOnly when the mains fails, for limited hours a year | What it changes for maintenanceServiced by time as much as hours. Batteries, charger, fuel and coolant age while it waits |
| Prime | How the set runsAs the main supply for unlimited hours, with a varying load | What it changes for maintenanceOil, filter and coolant intervals arrive quickly; wear items need checks between services |
| Continuous | How the set runsAt a steady load for unlimited hours | What it changes for maintenancePlanned top-end work and overhauls by hours; oil analysis and trend records matter most |
A standby set used as a daily supply during long outages is being run harder than its rating assumes, and its service plan should change with it.
Maintaining a set that runs by the hour
On a prime-power Cat set the hour meter drives everything. Oil and filters are changed at the hours in the engine’s schedule, oil samples show wear long before a failure, and valve lash, injectors and turbochargers are inspected at their own intervals. Dusty mine and quarry sites shorten air filter and radiator cleaning intervals further.
The photo shows an on-site service on a large canopied diesel set of another make; the routine on a Cat set follows the same pattern, with filters and parts for its own engine. See generator servicing and generator maintenance.
- Oil, oil filters and fuel filters by running hours
- Oil sampling for analysis, where the site’s plan includes it
- Valve lash and injector checks to the schedule
- Air filter restriction and radiator cleaning on dusty sites
Cat engine groups and the set sizes they cover
| Engine group | Rough set size | Points for repairs |
|---|---|---|
| Smaller C-series (C4.4, C7.1 and below) | Rough set sizeUp to about 250 kVA | Points for repairsCompact engines for commercial standby; the serial number settles which parts fit |
| Mid C-series (C9, C13, C15, C18) | Rough set sizeRoughly 250–800 kVA | Points for repairsElectronic fuelling with an ADEM engine control module; turbocharged and aftercooled |
| Large C-series (C27, C32) | Rough set sizeRoughly 800–1,250 kVA | Points for repairsHigh-output V engines; charge-air cooling and turbochargers need to stay clean |
| 3500 series (3508, 3512, 3516) | Rough set sizeRoughly 1,000–2,500 kVA | Points for repairsLarge V engines with many injectors and sensors, common on mines and other large sites |
| C175 series | Rough set sizeSeveral megawatts | Points for repairsAmong the largest Cat diesel sets, usually paralleled with switchgear and a site power system |
| 3400 series (3406, 3412) | Rough set sizeOlder sets, roughly 250–800 kVA | Points for repairsMany are mechanically governed and are diagnosed with gauges, not a laptop |
Faults to watch for
Problems to look out for on Cat sets
EMCP shutdowns: Shutting down or tripping
The EMCP controller stops the set for low oil pressure, high coolant temperature, overspeed and electrical faults, and logs each event. Read the log before resetting.
Engine module faults: Control panel repairs
On electronic engines the ADEM module can derate or stop the engine for a sensor or wiring fault. The diagnostic code it passes to the EMCP points to the circuit to test, not straight to a part.
Fuel cleanliness: Fuel system repairs
High-pressure injection is intolerant of water and dirt. Bulk tanks on mines and plants need water drained and fuel kept clean.
Dusty-site cooling: Overheating
Radiator cores clog on mine and plant sites, and fans and belts work hard. Cleaning should follow the conditions, not just the hours.
Large alternators: Generator rewinding
Big sets carry big alternators. Insulation resistance tests and bearing checks belong in the maintenance plan, with rewinding if the windings fail.
Paralleled sets: Surging and hunting
Where several sets share a load, synchronising and load sharing are checked as a system. A frequency or kW imbalance often starts at one governor.
Our approach
How we work through a Cat set fault
- 01
Plan around the site
Inductions, permits, isolation procedures and shutdown windows are agreed before we arrive.
- 02
Read the event log
The EMCP event log, with the diagnostic codes the engine module passes to it, shows what tripped and when.
- 03
Rule out the basics
Fuel, oil, coolant, air and battery condition come first, because they cause many alarms.
- 04
Identify the parts
Parts come from the engine serial number and the alternator and set plates: genuine Cat parts or quality equivalents, stated on the quote.
- 05
Prove it under load
Many faults only show at load, so the repair is tested under load where the site allows, or with a load bank test.
Independent service
We Service & Repair All Generator Brands
Onsite Generator Repairs is an independent generator specialist. We repair, service and maintain Caterpillar equipment as part of our work on every make of generator.
Manufacturer warranty claims go through the manufacturer’s own network. If your generator is still under warranty, check the warranty terms before arranging work by anyone else.
Brand names and trademarks belong to their respective owners. Onsite Generator Repairs is an independent service and repair company.
Service areas
Where we work in Gauteng
FAQ
Frequently asked questions
Do you work on Cat sets at mines and industrial sites?
Yes. We work on site across Gauteng, including industrial and mining sites. Tell us about inductions, permits or shutdown windows when you book so the visit can be planned around them. See industrial generator services.
Is a Cat engine the same as a Perkins engine?
No. Caterpillar owns Perkins and some engines share engineering, but parts are not always interchangeable. Parts are ordered by the engine’s own serial number.
How often should a Cat prime-power set be serviced?
By running hours, at the interval for the engine model and its duty. Prime-power sets reach their intervals quickly, so a plan based on hours rather than dates works best, with oil analysis between services.
Can an old EMCP panel be replaced?
Yes. When an older EMCP fails and parts are scarce, a modern controller can be fitted. Its wiring, sensors and protection settings are matched to the engine and alternator, and the set is tested under load afterwards.
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Who we work for
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- 24/7 operations
- We Arrive Within 1–2 Hours (usually within 1 hour)
- Free callouts and quotations