Stirling, your mechanic should have realized something was wrong before returning the car to you. He needs remedial training on timing chain tensioners. Hopefully the installation of the head gasket and resealing of the upper timing chain cover were done correctly and oil leaks don't develop soon. I recommend you find another tech for future repair work. Fortunately you sensed something was wrong and M.B.DOC's advice prevented a major problem this time.

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Fred Hoelzle