Lots of OM606 engines have developed delivery valve seal failures including mine within about 6 weeks after they started using ULSD here. Then my return lines went and they were less than 2 years old. I replaced everything in December, fuel lines, filters, seals and return hoses and so far no more problems.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz