B48 and B38 petrol: the timing chain guide rail breaks
Typically above 60,000 km. It does not show up on every car.
critical
severity
above 60,000 km
mileage
700–2,900 EUR
repair cost
3 sources next to the write-up.
The fault
How you spot it
Plastic guide rails hold the timing chain in place. On these engines the plasticiser in the plastic leaches out over time, the rail turns brittle and then breaks into pieces. The pieces land around the chain and further down, in the oil sump and on the strainer of the oil pump, and the leached plasticiser also deposits on that strainer. Two kinds of damage come from this: without its guide the chain starts to flap, and less oil reaches the engine through the narrowing strainer. The first sign is a rattling noise on a cold start that goes quiet after a few seconds or once the engine has warmed up. It is heard best on a fully cold start in the morning, because the chain tensioner needs time to tension the chain. The problem is reported above 60,000 km. Replacing the chain costs between 700 and 2,900 euro, and is typically four figures, because the chain can only be reached by removing several engine components.
Which model
Who it affects
The card opens the generation, the engine or the transmission.
Engines and transmissions
Engine
B48A20
Engine
B48A20H
Engine
B48A20M0
Engine
B48A20M1
Engine
B48A20O0
Engine
B48A20P
Engine
B48A20T1
Engine
B48A20U1
Engine
B48B16M0
Engine
B48B20
Engine
B48B20A
Engine
B48B20M1
Engine
B48B20O0
Engine
B48B20O1
Engine
B48B20U1
Engine
B38A15
Engine
B38A15A
Engine
B38A15M0
Engine
B38A15M1
Engine
B38A15P
Engine
B38B15
Engine
B38B15A
Checklist
B48 and B38 petrol: the timing chain guide rail breaks
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Checklist
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Sources
How we know
Motorschmiede · BMW, BMW M, Alpina · Spezialist für MotorenB48 Motorschaden durch eine defekte Gleitschiene von der Steuerkette -BMW B48 Motor retten: Lassen Sie die Steuerkette alle 60.000 km überprüfen & vermeiden Sie teure Reparaturen! Unsere Profis sind für Sie da. Mehr erfahren!
EW-MotorenserviceSteuerkette BMW Benzinmotoren N20B20, B48 & B38 - MotorschadenSteuerketten Problematik bei N20B20, B48 & B38 BMW Benzinmotoren
What BreaksUsed Car Weakness Database46,895+ weaknesses models engines
Information, not an expert opinion
We write the descriptions, and we put the source next to them. A person reviews them before they go out. They are still information, not a technical expert opinion.
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