While checking timing chain wear on the transplanted 617.950 in my recently acquired 300SD W126, I noticed about 1/2" to 3/4" lateral movement in the chain just below the cam sprocket on the passenger side.

(With the marks at the cam sprocket perfectly aligned, the marks at the crankshaft showed it to be 2 degrees after TDC; so although some chain wear exists, it could be much worse.)

I don't yet have any detailed information on this engine and, based on what I saw, I now need to ask how the timing chain tensioner operates.

Question: Does the tensioner take up chain slack by use of engine oil pressure or does the long spring shown in a parts picture at the Fastlane site provide adequate pressure to compensate for slack? Do I possibly have a broken spring with this installed tensioner?

The engine ran well before the shutdown for a valve adjustment and a glowplug check/replacements.

Thanks for any info on this.

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Respect, protect, and maintain complex systems - whether natural or of German design, to benefit from their full potential.

1982 300SD W126.120 with an OM617.950 from a W116.120
1984 300SD W126.120 with an OM617.951