The copper washers under the injectors start to leak at around 100 000 kilometres, and sooty gas gets from the combustion chamber into the engine bay. The soot first collects in the injector sleeve and makes the seal worse there, and then it gets into the engine oil.
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From there the path leads to the turbo. A fine gauze filter sits in the banjo bolt of the turbo's oil feed pipe, and the soot blocks it. Measured on such a car, the oil pressure at the turbo at idle was 0.8 bar, while the specified minimum is 2.3 bar; after the gauze was taken out it became 3.4 bar. With that much less oil the bearing of the turbo fails, and that typically happens above 130 000 kilometres.
The early signs are the smell of diesel in the cabin and black, oily deposits around the injectors on the engine cover.
The repair is not just the turbo, and that is the most important part of it. The oil feed pipe and its banjo bolts, the sump, the oil pick-up strainer, the oil filter housing and the oil cooler, the intercooler, the particulate filter with the exhaust and the vacuum pump of the brake system all have to be cleaned or replaced, and all the injector sleeves, seals and copper washers have to be replaced. If any of these is left out, the new turbo goes the same way.
What to check
- Open the bonnet and look at the base of the injectors: a black, oily ring shows a leak
- Look at the engine cover as well: the black, oily trace appears there too
- Smell the cabin after a cold start: the smell of diesel points to the same thing