Bosch MW-Size Pump

The MW injection pump differs considerably from the M and A shown so far; however, the MW is very similar in design to the larger inline pump, the P-size unit. The MW pump was designed for higher injection pressures than the M and A units and is found on many automotive high-performance/high-output turbocharged engines produced by such manufacturers as Mercedes-Benz in its 300D and SD passenger cars, as well as by Volvo truck and marine engines, Navistar International, Mack Trucks, and Perkins diesel engines.

The MW pump uses a bolted flange/bushing installed into the top of the injection pump housing and does not have an access plate on the side of the pump housing that can be removed for individual pump adjustment as is the case with both the M and A pumps shown earlier. The bolted flange on top of the MW pump is slotted so that when loosened, the barrel and valve assembly can be rotated to ensure equal fuel delivery from each individual plunger and barrel assembly. In addition, each pump plunger prestroke can be set by the use of shims of varying thickness which are installed or removed from under each bolted flange on top of the pump housing.