Cummins diesel engine repair and overhaul
Diagnosis, overhaul, fuel system and ECM work on Cummins engines in generator sets, marine installations, plant and trucks — in our Sharjah workshop and on site across the UAE. Independent, and measured before it is quoted.
Why engines reach us
What a Cummins engine comes in for
Most arrive with a symptom rather than a diagnosis. These are the ones that put an engine on the list.
Down on power, burning fuel
Falling output and rising consumption for the same load. Often the injection equipment rather than the engine — and injectors and pumps are testable on our own benches without stripping anything.
Smoke and hard starting
Smoke under load, or smoke that persists once the engine is hot. Compression and combustion problems, which is head and valve territory before it is anything heavier.
Blow-by and oil consumption
Pressure or oil mist from the crankcase breather rising with load, oil use climbing between services. That points at liners, pistons and rings — the bottom end is involved.
A fault code and a shutdown
On QSK and other electronically controlled engines the controller stops the machine and names a circuit. A code names a circuit, not a broken part, so the circuit gets verified before a control unit is condemned.
Fuel system testing on the bench, mechanical testing on the engine, and fault code and live data work where the engine is electronically controlled. That order matters commercially: a good many engines arrive described as worn out and leave after injection equipment has been calibrated rather than after an overhaul. See engine diagnostics →
The distinction that changes the quote
Head work, or a full overhaul?
These get quoted as though they were the same job and they are not. The difference is the bottom end — and getting it wrong is money spent twice.
Cylinder head work
From the head gasket up
- Heads stripped; valves and seats reconditioned
- Decks surfaced to gasket specification
- Castings pressure tested, with the hold time recorded
- Injector tubes and sleeves replaced, protrusion checked
- Injectors stripped, tested and calibrated on the bench
Restores compression and combustion. Does not address liner, piston or bearing wear.
Full overhaul
Down to the block
- Pistons, rings and liners out; liner bores measured
- Crankshaft out, measured, ground to an undersize where recoverable
- Main bearing bores checked and line bored if out of true
- Connecting rods resized, small end bushes fitted and bored
- Rebuilt to specification, then run and tested
Which one you need is decided by measurement, not by a running-hours figure.
The full scope
What we do on a Cummins engine
The engine work is the service. The machine shop behind it is what lets us finish the job without sending your components out.
Diagnosis & testing
- ECM fault code reading and live data on electronically controlled engines
- The circuit verified before a control unit is condemned
- Mechanical testing and fault isolation on the engine
- Injectors and pumps tested on the bench rather than judged by symptom
- A straight answer on whether an overhaul is even the right job
Overhaul & rebuild
- Full overhaul — strip, measure, machine, rebuild and test
- Cylinder head rebuilding — valves, seats, decks, pressure testing
- Liners, pistons and connecting rods measured and dealt with
- Crankshaft and main bearing work where the readings allow it
- Returned with the measurements that decided each step
Systems & components
- Injectors and injection pumps stripped, tested and calibrated on our own benches
- Holset is a Cummins brand, and Holset units off these engines are stripped, rebuilt and balanced on our own bench
- Aftercoolers, heat exchangers and oil coolers cleaned and pressure tested
- Starter motors and charging alternators overhauled and tested on the bench
- ECM, ECU and governor work
Where the engine sits
- Generator sets and standby installations
- Marine auxiliaries and propulsion units
- Drilling and construction plant
- Heavy trucks and commercial vehicles
- On-site attendance across the UAE, with the heavy work coming back to Sharjah
And the machining, when the job needs it
Crankshaft grinding, liner bore machining, line boring, head surfacing and connecting rod resizing happen in this building rather than at a subcontractor. That is not a separate service you buy — it is why a Cummins overhaul here does not stall in somebody else's queue, and why a component you already own can often be saved instead of ordered. On a KTA or an NTA855 that matters more than it sounds: a KTA crankshaft is not a part anyone wants to source new if the one in the engine can be ground.
Whole generator set work — alternator, control panel, load testing, genset troubleshooting — is covered in the generator repair section rather than here, and brand by brand on Cummins generator and genset repair. If the engine is in a vessel, marine main engine repair covers the engine-side work.
What arrives here
Cummins engines we work on
Send the engine model, CPL and serial number and you will be told plainly whether yours is a job we take, before anything is moved.
N series — NTA855
The 14-litre inline six that ran for decades in gensets, drilling rigs, marine auxiliaries and industrial drives. Still everywhere in this region, and still economically repairable — which is the point.
K series — KTA19, KTA38, KTA50
The heavy frame: the 19-litre inline six, and the V12 and V16 machines in large gensets, marine propulsion and auxiliaries, and heavy plant. The engines where parts lead time hurts most.
QSK series
The electronically controlled descendants of the K family, which brings ECM diagnostics and electronic fuel control into the job alongside the mechanical work.
Mid-range, B and C series
In plant, gensets and commercial vehicles. Ordinary workshop work, and the family we see most in mixed fleets.
The expensive decision on an older Cummins is almost never “repair or replace the engine”. It is whether this crankshaft, this block and this head are still within limits — a measurement, not an opinion. A crankshaft turns on ovality, hardness, bend and crack depth, and on how much material remains above Cummins' bottom permitted undersize. A block turns on liner bore wear, taper and ovality, and on main bearing bore alignment. A head turns on flatness, seat recession and cracks. Every one of those readings is taken here, and if a part is past recovery you will be told so — on a KTA or an NTA855, knowing that early is worth more than any discount.
A fair question, answered factually
Independent specialist, or authorised dealer
We hold no Cummins dealership and we are not a distributor. Here is where each route genuinely wins.
Straight answers
Frequently asked questions
Are you a Cummins dealer?
No. We hold no brand dealership of any kind, and we say so on our own site. We are an independent workshop that repairs and overhauls Cummins engines.
Will using an independent workshop void my warranty?
If the engine is still under manufacturer warranty, that is a real risk and you should use the authorised network. Out of warranty, it is not an issue.
Do you use genuine Cummins parts?
We quote genuine parts where you want them or your policy requires them, and quality aftermarket where that is the sensible choice — and the quotation states which is which. We are not restricted to one supply channel.
Can you rebuild a KTA or NTA cylinder head?
Yes. Heads are stripped, valves and seats reconditioned, decks surfaced and units pressure tested, with the machining done here.
Can you repair a Cummins ECM?
ECM fault diagnosis and repair is handled — see ECM, ECU and governor repair. A fault code names a circuit, not a broken part, so we verify the circuit before condemning the control unit.
My Cummins generator will not hold load — is that this page?
That is a genset question rather than a brand question and it is answered under generator repair.
Get a Cummins engine quoted
Engine model, serial number, application, running hours and the symptom. Photograph the data plate — the CPL and serial number tell us more than a description does.