Engine - Updated Timing Chain Tensioner

91mercedes03

REF. NO.: 05/87


TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS

DATE: October 1991


SUBJECT: ALL MODELS WITH ENGINE 116.96 AND 117.96
TIMING CHAIN NOISE WHEN STARTING ENGINE
MODIFIED CHAIN TENSIONER


As of February 1989, a modified chain tensioner is installed in the above-listed engines. A number of modified chain tensioners were also installed in production during the period October to December 1987 as per the Effective Serial Number Range.

Figure 1:

Complaints of timing chain noise when starting the engine can be traced to the previous version timing chain tensioner. When shutting off the engine, oscillation from the crank assembly, in some cases, causes the thrust pin (12, Figure 1) to compress excessively.

An additional filler piece (7) in the compression spring limits the rearward travel of the thrust pin and reduces the compression area so that the chain tensioner reacts faster. Furthermore, an additional compression spring (5) in the supply valve allows a quicker pressure build-up (Figure 1).


In case of complaints about timing chain noise or when performing repairs to the chain drive, use only the modified chain tensioner. The modified chain tensioner must also be used in earlier production engines.


Effective Serial Number

Model Engine Engine End Number Chassis End Number

107.048 117.967 045973 A 099193

126.035 116.965 069128 A 467531

126.039/045 117.968 065319 A 467294


Effective Serial Number Range (October - December 1987)

Model Engine Engine End Number Chassis End Number
From To From To

107.048 117.967 029616 - 032299 A 078204 - 081360

126.035 116.965 051521 - 054379 A 374139 - 386918

126.039/045 117.968 040146 - 043441 A 374049 - 386656


Parts Information

Part Name Part Number

Chain tensioner (kit) 116 050 18 11


Only the modified chain tensioner is available as a spare part.