The N20 is the 2.0 turbo petrol used in 320i, 328i, 520i, X3 28i and several other cars before the B48 replaced it. The N26 is the low-emission twin of the same engine. Buyers look for a used N20 when the chain guides have already failed in their own car, or when they want a complete unit instead of another guide kit.
Which N20 you are buying
Early N20 engines are the ones with the reputation. BMW later changed the chain guide and tensioner. A later N20B20A or N20B20B is not automatically safe, and an early one is not automatically ruined. The question is whether this particular engine still has the original guides, and whether it rattles.
The N26 is not a cosmetic label. It was built for stricter emissions rules and the catalyst and engine computer are paired with that spec. Do not fit an N20 into an N26 car, or the other way around, without the workshop confirming the control unit and the exhaust.
The noise
The chain noise people mean is a rattle at cold start, from the front of the engine, that can last until oil pressure comes up. A short second of it on a very cold morning is worth noting. A rattle that goes on, or a rattle that is there when the engine is warm, is a reason to look at another unit.
If the seller says the chain was done, ask for the parts list. Guides, tensioner, chain and the oil-check valve that feeds the tensioner belong in that job. A chain fitted without the guide update is the same problem waiting.
Parts that must match
The N20 in an X3 often has a different oil pan from the N20 in a 328i. Automatic and manual cars need the right flywheel or flexplate. The turbo, the high-pressure pump and the intake should be the ones your car's wiring expects. We photograph the stamp and the pan before an engine leaves Hamburg.
Send the 17-character VIN. We match the code, and we say if the unit in the shop is the wrong pan or the wrong injection spec.
Full N20 and N26 guide · N20B20 engines in the shop
The fitting week
Change the oil and filter before the first road test, and replace the coolant. The N20 oil-filter housing and the valve cover are the leaks that come back if the old gaskets are reused on a fresh block. The charge pipe should be the later, less brittle one if you are transferring parts from the broken engine.
Clear any chain-related fault codes only after the engine has idled and come up to temperature. A code that returns on the second cold start is information. Do not clear it again and deliver the car.
The yard is at Andreas Meyer Straße 38, 22113 Hamburg. Call or WhatsApp +49 15510 030835, or email autowerkeengines@gmail.com, Monday to Friday, 9:00 to 16:00 CET. Shipping is 249 € per order. We are an independent seller, not BMW AG.