This MINI Cooper S came in with the engine overheating and the gearbox not shifting right. Here is how we diagnosed and repaired both, together.
Job completed: July 2026
| Car | MINI Cooper S (petrol) |
|---|---|
| Symptom | Severe engine overheating, and a gearbox not shifting cleanly |
| Fault found | Seized pistons and worn big end bearings from oil starvation inside the engine, and a worn automatic gearbox |
| Repair done | Full engine overhaul (seized pistons and worn bearings replaced) and full gearbox overhaul, road tested before handover |
| Parts | OEM-grade replacement parts |
| Time taken | Timeline set after strip-down; both jobs done in the same visit |
| Cost | $15,255 nett total for both engine and gearbox overhaul on this job |
| Warranty | 3 years / 60,000km on the engine overhaul; 2 years / 40,000km on the gearbox overhaul |
The owner brought in a MINI Cooper S that had been running hot for a while. The overheating had grown severe. On top of that, the gearbox was not shifting smoothly.
The owner had already taken it to another workshop before us. The owner then brought the car to us for a proper diagnosis.
This MINI Cooper S pairs its petrol engine with an automatic gearbox. Inside the engine, pistons move up and down in cylinders, and the connecting rods and big end bearings keep everything running smoothly on the crankshaft. The whole system depends on a clean supply of oil at the right pressure.
Inside the automatic gearbox, clutch and friction packs grip and release to change gears. Both the engine internals and the gearbox parts are wear items. When the oil supply is interrupted or gets too low, the engine can starve for lubrication very quickly, and the damage that follows is serious. A gearbox that is also misbehaving has a separate problem of its own with worn internals.
We inspected the car and the story was clear: the engine had already been run hot, so we stripped it down to find out how far the damage had gone.
Inside the engine we found seized pistons and worn big end bearings from oil starvation. The crankshaft was damaged too. These were not parts we could leave. The only real fix was a full engine overhaul: strip, resurface or replace what was damaged, and rebuild it properly.
On the gearbox, we stripped it down and found the internals worn. The trouble the owner felt came from those worn parts no longer gripping cleanly. Two separate problems, both needing a proper fix, not a patch.
Oil starvation is one of the fastest ways to destroy a petrol engine. Once the oil pressure drops, the bearings and pistons start to wear against the metal surfaces they normally ride on. Once that oil film is gone, the heat builds fast.
The gearbox trouble was a separate issue with its own cause. The clutch and friction packs inside the automatic gearbox wear down over many gear changes. Once the friction material is thin enough, the gearbox can no longer hold its gears cleanly.
Both faults were repaired together. Doing both at the same time was the practical choice: the car was already in, and the owner got both warranties starting together.
We did a full engine overhaul and a full gearbox overhaul together.
On the engine:
On the gearbox:
After both jobs: road tested the car before handing it back to the owner.
The engine overhaul carries a 3 year / 60,000km warranty. The gearbox overhaul carries a 2 year / 40,000km warranty.
On this MINI the two overhauls together came to $15,255 nett. What another car costs depends on how far the engine damage has gone and what is worn inside the gearbox: a job caught before the crankshaft is damaged costs less, and once the crankshaft needs work the figure moves up.
We strip and inspect the engine first, then quote before any parts are ordered. That way you know exactly what you are paying for and why, rather than getting a blanket estimate that may not match what the car actually needs.
The early signs of engine oil trouble are the oil pressure warning light and the engine temperature rising. If either of those comes on, the right move is to stop the car and not drive it further until the cause is found. A car driven on low oil pressure can go from a repair to a full rebuild very quickly.
For the gearbox, watch for any slip on acceleration, a jerk when pulling away, or a delay before the gearbox engages drive or reverse. Keeping up with ATF changes on schedule and having any slipping checked early is the cheapest way to keep the gearbox out of a full overhaul.
This MINI Cooper S (Engine overhaul and gearbox overhaul) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. For MINI, we use dealer-level ISTA diagnostics. We hold a 4.9★ rating from 1,775+ Google reviews.
WhatsApp us your car model, year and symptoms. We will tell you what is likely wrong and the cost before any work begins. The engine overhaul carries a 3 year / 60,000km warranty. The gearbox overhaul carries a 2 year / 40,000km warranty.
On this MINI the engine and gearbox overhauls together came to $15,255 nett. The figure for another car depends on the extent of the internal damage, so we strip and inspect before quoting. We strip and inspect the engine first, then quote before ordering parts. The engine overhaul carries a 3 year / 60,000km warranty.
It depends on the condition of the block and crankshaft. If the block is good and the crankshaft can be resurfaced, an overhaul with new pistons, bearings and seals can restore the engine properly. We check the block and crank first, then advise you on which route makes sense for your specific car.
Yes. Both warranties start from the same date, and the car is off the road once instead of twice. On this MINI Cooper S we did both together, and the owner drove away with a 3 year / 60,000km engine warranty and a 2 year / 40,000km gearbox warranty.
Oil starvation is what did it here. Once the lubrication film on the bearings breaks down, the damage happens fast. If an oil pressure warning ever appears, stop the engine immediately: driving past the warning light is what turns a fixable oil issue into a full engine overhaul.
Yes. A full engine overhaul at our workshop carries a 3 year / 60,000km warranty, whichever comes first. The gearbox overhaul carries a separate 2 year / 40,000km warranty. We confirm the exact terms before work starts.
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