Cooling System - Production Changes
83mercedes02TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE: June, 1983 REF. NO. 20/24
SUBJECT: ENGINE COOLING SYSTEM ENGINES 617.951/952
Since February 1983, a modified visco fan clutch (higher viscosity), a 9-blade plastic fan, a smaller water pump pulley, and shorter V-belts have been installed on engine 617.951.
The modified visco fan clutch and the 9-blade plastic fan will be installed on engine 617.952 as of July 1983.
Production Phase-In
Chassis As of Chassis End No.
123.133
123.153 Approx. July 1983
123.193
126.120 039449
FIGURE 1:
Due to the smaller pulley diameter (B, Fig. 1), shorter V-belts (9.5 x 1000, serrated) are required (previously 9.5 x 1035, solid belt). The pulley ratio is now 0.9 (previously 1.09)..
FIGURE 2 PREVIOUS FAN WITH VISCO FAN CLUTCH:
FIGURE 3 MODIFIED FAN WITH VISCO FAN CLUTCH:
The visco fan clutch is still temperature controlled. Due to the lower pulley ratio, the fan operates at a higher speed in all ranges. Maximum speed is approximately 4000 rpm (previously approx. 3500 rpm).
The 9-blade plastic fan (previously 6-blade light alloy fan) has a cast-in sheet metal hub (Figure 3). It is mounted to the visco fan clutch with four (M8 x 15) bolts and washers (previously (M8 x 18) bolts and spring washers).
Repair Instructions
Subsequent installation of the modified visco fan clutch together with the 9-blade fan, smaller pulley, and shorter V-belts is possible.
Parts Information
Quantity Description Part Number
1 Pulley, water pump 617 205 09 10
2 V-belt, 9.5 x 1000 004 997 85 92
1 Visco fan clutch 000 200 19 22
1 Fan (9-blade) 110 200 03 23
4 Bolt, M8 x 15 000933 008131
4 Washer, A 8.4 000433 008406