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Known fault

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

Checklist

B48 and B38 petrol: the timing chain guide rail breaks

What you would check for this fault. Take it to the car.

Before you buy

Checklist

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vinkodex.com · Before you buy it, see what can go wrong.

Sources

How we know

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.

  • A fault on the list does not mean the car you are looking at has it.
  • A fault missing from the list does not mean the model is fault-free. Write-ups are made model by model. Not all of them are done.
  • You decide whether to buy. This is no substitute for an inspection. That needs a workshop and a history check.
Details in the terms