Tick tick tick noise in my 1980 300TD wagon, at about 6 beats per second at idle, and that continues in proportion to engine speed, won't go away.

The sound does not seem to be affected by engine temperature or load

Adjusted valves, no difference. cracked injectors one @ a time, about equal, but did not affect noise.

Removed oil pan, and found a circlip that fell off the oil pump chain tensioner. Replaced that, refilled oil, no change in the noise. There was no evidence of rod bearings shedding metal, (dissected oil filter) what I could see of 2 pistons looked OK. It was generally quite clean in there.

Baffled where to look next.

Stethescope picks up the noise at the very center of the round portion of the valve cover, and also on a curved corrugated aluminum pipe below the air filter that I think is part of the turbo. The steel injector lines are all about equally very loud.

Local (West Palm Beach) mechanics that have heard it say it sounds internal.

Runs pretty well, good oil pressure, runs cool. The 2 rods I could reach
did not seem loose.

Where to look next ???

See Tinkerbell or any alligators nearby?

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1993 MB 300D 245K died.

I just got the head off mine that has the same noise. Looks like it sucked something in and cut up the walls. I won't know until I clean it up though. Really sad

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84 300sd 2.47 dif 360k
26 mpg needs lots of love
given to me in pitty

89 civic hatchback auto 140k
33mpgs soon to be low to mid 40's
been in the family since mile 1

85 300d with unknown knock. driven over 30k with knock and still going. sold for $800