I've been chasing the problem of a very loud abnormal sound in the 617 diesel engine for some time. I initially took the car to a local indy who listened carefully and determined the problem was Transmission Torque Converter Flex Plate failure. This proved to be an inaccurate diagnosis...also, He did not seem too interested in offering a pay-to-play diagnostic service to further investigate.

After much discussion here in the forum, it was determined the real problem was a failed fan clutch. I finished replacing the water pump and the fan clutch yesterday, filled the car with 50/50 coolant mix and WOW!...the engine sounds like NEW!