Since the earliest petrol and diesel engines, pistons have been the component at the heart of the combustion cycle — translating the explosive pressure of burning fuel into the rotary motion that drives the crankshaft. Each piston travels the full bore of its cylinder hundreds of times per minute, under extreme heat and load, guided by piston rings that seal the combustion chamber and regulate oil consumption. When the rings wear or the piston itself becomes damaged — typically through pre-ignition, lubrication failure, or overheating — the consequences are unmistakable: blue smoke from the exhaust, a measurable drop in compression, and oil consumption that rises from drops per thousand miles to litres. Piston replacement is a specialist workshop operation requiring the engine to be substantially disassembled, which is why getting the OE reference right at the outset is critical: bore diameter, compression height, and pin bore must all match the engine's internal geometry exactly. MAHLE and KOLBENSCHMIDT are the two dominant OE piston manufacturers in Europe, supplying the majority of volume car manufacturers directly from their factories; both brands also market replacement pistons carrying the same OE cross-references. Yenmak and IPSA offer cost-effective alternatives that cover a broad application range for older or high-mileage engines.
Pistons are defined by bore diameter, compression height (crown to pin centre), piston pin diameter, and ring groove dimensions — all of which are specific to the engine build code rather than just the model and year. Use your full engine code (stamped on the block) alongside make and model in the vehicle selector on this page. It is also essential to know whether the engine has been rebored at any point, as oversized pistons with larger bore diameters may have been fitted, and standard OE references will not be correct in that case.
OEM pistons from MAHLE or KOLBENSCHMIDT are produced to the vehicle manufacturer's exact metallurgical specification, including the aluminium alloy grade, ring groove coating, and pin bore finish. Quality aftermarket pistons from the same makers or from YENMAK replicate these parameters precisely and carry cross-reference OE numbers. Budget alternatives may use different alloy grades or less precise ring groove dimensions, which can lead to elevated blow-by, accelerated oil consumption, or premature ring failure in high-stress applications.
Yes, pistons should always be replaced as a complete set for the relevant bank or engine. Installing a new piston alongside worn originals creates a mismatch in thermal expansion and ring tension that leads to uneven compression across cylinders, rough running, and accelerated wear on the newly fitted piston. The labour involved in accessing pistons also makes replacing a single unit economically irrational — the disassembly cost is the same whether you fit one or all of them.
Persistent blue or grey smoke from the exhaust on a cold start that reduces as the engine warms is the classic sign of worn piston rings allowing oil to enter the combustion chamber. A compression test will confirm low readings across one or more cylinders. Heavy oil consumption — needing a top-up between services — combined with fouled spark plugs on petrol engines or injector deposits on diesel engines also points to ring and piston deterioration. A knocking sound from the engine, particularly at low speed and load, can indicate piston slap — excessive clearance between piston and bore wall in a worn engine.
Showing 100 of 10,321 Piston OE numbers. Enter the OE on the main OE search to jump to any reference.
