Bosch R20, R21, R22, R23, R24, R25 & R28
Fuel Injection Pumps
improvements throughout the decade
The PES6KL 70B120 R20Y and future pumps carried over the larger access port for plungers and springs. Minor adjustments can be seen in the bulk of the pump body, which was significantly reduced. The R20Y was fitted with both start and stop solenoids and has force-feed oil lubrication.
The R21 carried over many characteristics from previous pumps but has a different three-dimensional cam from the R20. The R22Y brought minor improvements specified for the U.S. market. Characteristics include no starting solenoid, 4mm ball thrust valves, and a different three-dimensional cam. The R23 followed the R22Y with subtle changes that improved performance. The R24Y was modified for the U.S. market. Characteristics include no start solenoid, 4mm ball thrust valves, and a different three-dimensional cam. When installed on automatic transmission vehicles the vacuum control at the venturi control unit and throttle control linkage with dead travel are eliminated. The R25 increased the number of full load adjustment notches and replaced the hex. head governor screw plug with a flange. Lastly, the R28 use a different 3D cam from its predecessors.
The first set of images shows off a recently completed R20Y.
The second set of images shows a PESK6KL 70B120 R24Y for a US market W113 280SL "Pagoda". While this exact pump is headed back to the client, we have another R24Y available for purchase through our shop. Contact us today for details.
Here we have another R24Y shown in the midst of final testing. Once the pump is cleaned, replated, and reassembled it is meticulously tested and calibrated to ensure optimum performance.
Check out our test bench pages to learn more about the benches, how we test our pumps, and get an inside look at how we restored the test benches themselves to best suit our needs.
Recalls and updated maintenance recommendations are not modern creations. Here we have a document sent out in 1973 referring to changes in the recommended maintenance for fuel injection pumps for a variety of high end models like the 300SEL, 280SL, and 280SE.
After five years in the wild, it was found that some fuel injection pumps were being damaged due to a lack of lubrication caused by a blocked oil line. This document was sent to dealers with updated guidance on how to prevent this during regular maintenance services.