Original 190sl Fuel Pump Restoration
The fuel pump with out the priming lever was supplied with the car and was not original. This was replaced with an original spare fuel pump with priming lever. The fuel pump remained unchanged except for the discontinuation of the water drain plug. The version for my chassis number consisted of a pump without this water drain.
The photo below of the fuel pump stripped does not do justice to the grime and condition before chemical cleaning and glass blasting the components. The fuel pump housing's flat mating surfaces were dressed with emery paper on a flat surface to reduce the chance of leakages.
All plating was done using a home yellow passivate plating kit from Frost Auto Restoration. The factory finish was yellow cadmium, which is unobtainable nowadays due to its toxic nature. Repair kits are still available from Mercedes Benz and at first sight appeared to be incomplete. Mervyn Wright at Jacksons Bournemouth was kind enough to check other kits and these too where short of a few parts. Three lens head screws and washers are provided so one must recycle three from the pump being rebuilt. The old strainer included a soldered pressure spring. The kit includes the strainer only and one must reuse the pressure spring from the old pump and carefully soldering onto the new strainer. The small countersunk screws require one to be recycled. One other part not supplied with the kit that may be required if you intend to re-plate all parts, is the hand lever circlip. In addition to this fibre washers for the end cap and hollow/fixed screws need to be ordered separately.
To assist in rebuilding the fuel pump I followed an excellent article by Ray Ilich on the Ponton website. This article was based on a Mercedes Benz Ponton, in fact this pump is shared with the following models; 170S, 170Sb, 170S-V, 180, 180a, 180b, 180c, 190, 190b, 190SL, 219, 220, 220a, 220S and others. The hardest part during rebuild was to engage the diaphragm onto the push rod. This part is important otherwise you will not have pressure when priming the pump. There does not appear to be any information in the factory workshop manuals on the fuel pump, but ensure that the fuel pump pressure is at the factory specification of 2.8 psi. This will be checked once the fuel pump is fitted and engine started with a fuel pressure gauge.
Photos below show the cleaned, plated, rebuilt and tested pump ready for action.
