A full OEM+ engine rebuild and cosmetic restoration on a 2009 Cooper S convertible. Rebuilt to factory standard, with a handful of tasteful upgrades where it makes sense.
A 2009 Mini Cooper S convertible — bought with two broken engines and zero mechanical experience. The plan? Rebuild one of them. How hard can it be?
Harder than expected. But that's never stopped me.
The goal is an OEM+ Cooper S — everything rebuilt to factory standard, with a handful of tasteful upgrades where it makes sense. No track mods, no forced induction upgrades, no wholesale character changes. Just a properly sorted convertible Cooper S that drives the way it should have left the factory — only better.
Every part sourced, every torque figure documented, every mistake on camera.
Subframe dropped, engine and gearbox out as one unit, everything bagged and labelled. The bits people forget to photograph, photographed.
Head off, bottom end apart, measure everything. Bore, crank journals, piston-to-wall — every number written down before a single part is ordered.
Head skimmed and pressure tested, block honed, then reassembly with new bearings, rings, timing chain and gaskets — all to factory torque.
Ancillaries refreshed while it's out, engine back in, fluids, and the moment the whole project is about.
Paint correction, roof clean and re-proof, headlight restoration, wheel refurb and interior detail.
Search the parts documented on this car by name, category or note. SHOP links go to the exact part used, or the closest OEM-equivalent listing — always confirm fitment against your VIN before ordering.
The parts that go back inside the engine — internals, timing and everything that seals it up.
| Part | Part number | Category | Price | Shop | Install |
|---|---|---|---|---|---|
| Pistons (rings included) New pistons fitted rather than re-ringing the originals — the set came with rings, so no separate ring set was needed. Standard bore, all four cylinders. OEM Fitted | Add part no. | Engine internalsBottom end | Add price | Shop | Watch |
| Main bearing set Graded by crank journal measurement — order after inspection, not before. OEM To do | Add part no. | Engine internalsBottom end | Add price | Shop | Watch |
| Big end (con rod) bearing set Plastigauge every journal. Con rod bolts are single-use. OEM To do | Add part no. | Engine internalsBottom end | Add price | Shop | Watch |
| Crankshaft thrust washers Check crank end float with a dial gauge. OEM To do | Add part no. | Engine internalsBottom end | Add price | Shop | Watch |
| Valve stem seals (x16) The cheapest fix for oil consumption while the head is off. OEM To do | Add part no. | Engine internalsCylinder head | Add price | Shop | Watch |
| Head gasket (multi-layer steel) Matched to the skim thickness taken off the head. OEM To do | Add part no. | Engine internalsCylinder head | Add price | Shop | Watch |
| Cylinder head bolt set Torque-to-yield. Never reuse. Angle gauge required. OEM To do | Add part no. | Engine internalsCylinder head | Add price | Shop | Watch |
| Timing chain kit Chain, tensioner, guide rails and sprockets. The famous "death rattle" fix. OEM To do | Add part no. | Timing & VANOSTiming | Add price | Shop | Watch |
| Timing chain tensioner (latest revision) Fit the updated part number even if it comes in the kit — check the revision. OEM To do | Add part no. | Timing & VANOSTiming | Add price | Shop | Watch |
| VANOS solenoid Cleaned and tested — replaced if the screen was damaged. OEM To do | Add part no. | Timing & VANOSTiming | Add price | Shop | Watch |
| Timing cover gasket & crank seal Front crank seal replaced with the cover off — cheap insurance. OEM To do | Add part no. | Timing & VANOSTiming | Add price | Shop | Watch |
| Full engine gasket set Covers sump, cam cover, intake and exhaust manifold gaskets in one box. OEM To do | Add part no. | Gaskets & sealsSeals | Add price | Shop | Watch |
| Rear main crank seal Only accessible with the gearbox off — do it now. OEM To do | Add part no. | Gaskets & sealsSeals | Add price | Shop | Watch |
| Cam cover (valve cover) gasket Plus the spark plug tube seals — a common oil-in-plug-well leak. OEM To do | Add part no. | Gaskets & sealsSeals | Add price | Shop | Watch |
| Turbo oil feed & return line seals Copper crush washers and banjo bolts — never reuse. OEM To do | Add part no. | Gaskets & sealsSeals | Add price | Shop | Watch |
Ancillaries replaced while the engine was out — cooling, fuel and induction.
| Part | Part number | Category | Price | Shop | Install |
|---|---|---|---|---|---|
| Water pump (with friction wheel) The friction-drive wheel wears — replace pump and wheel together. OEM To do | Add part no. | Cooling, fuel & inductionCooling | Add price | Shop | Watch |
| Thermostat & housing Plastic housing cracks with age. Comes with the sensor on later units. OEM To do | Add part no. | Cooling, fuel & inductionCooling | Add price | Shop | Watch |
| Coolant (BMW/Mini blue spec) Mixed 50/50 with distilled water. Do not mix colours. OEM To do | Add part no. | Cooling, fuel & inductionCooling | Add price | Shop | Watch |
| High-pressure fuel pump (HPFP) A known weak point on the Prince engine. Tested before deciding. OEM To do | Add part no. | Cooling, fuel & inductionFuel | Add price | Shop | Watch |
| Injector seal kit Teflon seals and O-rings for all four direct injectors. OEM To do | Add part no. | Cooling, fuel & inductionFuel | Add price | Shop | Watch |
| PCV / crankcase breather valve Built into the cam cover on some years — check yours. OEM To do | Add part no. | Cooling, fuel & inductionInduction | Add price | Shop | Watch |
Fluids, filters and wear items for the first start and the first service after it.
| Part | Part number | Category | Price | Shop | Install |
|---|---|---|---|---|---|
| Engine oil — 5W-30 BMW LL-04 Full synthetic. Break-in oil first, then this after 500 miles. OE spec To do | Add part no. | Service itemsService | Add price | Shop | Watch |
| Oil filter Mann or Mahle — the OE suppliers. OE spec To do | Add part no. | Service itemsService | Add price | Shop | Watch |
| Spark plugs (NGK, set of 4) Standard heat range for a stock engine. OE spec To do | Add part no. | Service itemsService | Add price | Shop | Watch |
| Ignition coils (set of 4) Replaced as a set — a misfire on a fresh engine is not worth chasing. OEM To do | Add part no. | Service itemsService | Add price | Shop | Watch |
| Air filter Standard panel filter in the standard airbox. OE spec To do | Add part no. | Service itemsService | Add price | Shop | Watch |
| Serpentine belt & tensioner Belt, tensioner and idler while the engine is on the stand. OEM To do | Add part no. | Service itemsService | Add price | Shop | Watch |
The tools that were specific to this rebuild. General garage tools live on the Tools page.
| Category | Tool | Spec | |
|---|---|---|---|
| Timing | Mini N14 / N18 timing tool kitCam locking bar, crank locking pin, tensioner tool. Non-negotiable. | Essential | Shop |
| Lifting | Engine crane (1 tonne folding)Folds away — important in a single garage. | Essential | Shop |
| Lifting | Engine stand (rotating)Lets you flip the block for the sump and bottom end. | Essential | Shop |
| Torque | Torque angle gaugeFor head bolts and con rod bolts — torque-to-yield needs degrees, not just Nm. | Essential | Shop |
| Assembly | Piston ring compressorBand type or tapered sleeve for the 77mm bore. | Essential | Shop |
| Assembly | Piston ring expander pliersStops you snapping a £40 ring set on the bench. | Recommended | Shop |
| Measuring | Plastigauge (green & red)Bearing clearance check on every journal. | Essential | Shop |
| Measuring | Feeler gauge setRing end gap and end float. | Essential | Shop |
| Measuring | Dial gauge & magnetic baseCrank end float and checking the deck is flat. | Recommended | Shop |
| Head | Valve spring compressor (overhead cam type)For the stem seals with the head on the bench. | Essential | Shop |
Bringing the outside back to match the inside. Products here overlap with the Detailing page — this is what's specific to the Mini.
| Category | Product | Spec | Fitted | |
|---|---|---|---|---|
| Roof | Convertible fabric roof cleaner & protector kitClean, dry fully, re-proof. The R57's roof is the first thing people notice. | Recommended | To do | Shop |
| Lights | Headlight restoration kitWet sand, polish, then a UV clear coat so it lasts more than a summer. | Recommended | To do | Shop |
| Paint | Paint correction compound & polishTwo-stage on the bonnet and boot where the swirls live. | Recommended | To do | Shop |
| Wheels | Alloy wheel refurb paint (OEM silver)Kerbed edges filled, primed and refinished at home. | Recommended | To do | Shop |
| Trim | Black plastic trim restorerWheel arches, side skirts and the scuttle panel. | Recommended | To do | Shop |
| Badges | Genuine Mini badges (front & rear)Faded and peeling ones replaced with OEM. | OEM | To do | Shop |
Every stage of Project Sunseeker, filmed as it happens.