During the appraisal of our 1967 Mercedes 250SL, it was noted that the nearside front wheel was binding. Pete removed the wheel for a closer inspection and found that the inner piston was seized in the calliper body. He attempted to free this while the calliper remained on the car. He removed the pad retaining springs and pins and the pads but no amount of fiddling would push the piston back – operating the foot pedal didn’t affect a push-out either.
The calliper was removed from the car and separated on the bench where better access to each piston was available. Pete removed the dust seals and gave them a liberal coating of penetrate oil and allowed it to soak while he worked on a fix for the fuel pump.
Regarding the pump, Pete’s gasket repair from last week didn’t allow enough clearance for the pump to spin on the motor and as such there was no fuel supply. He stripped the base plate from the pump again and removed that gasket repair. He actually found an o ring that was a close match to the size needed although it did require hand stretching with the addition of some heat and fitted perfectly. The pump was remounted, pipes connected for the final time and the guard refitted.
Back to the calliper, given time to soak and the addition of plenty of force Pete managed to break the rust that was holding it solid, each piston was slid out by hand, cleaned with a scotch pad so the surface wasn’t damaged and refitted back in the calliper body with some clean lubricant. The dust seals were cleaned and greased and refitted, before Pete fully assembled the calliper and fitted it back in the car. The brakes were bled, the wheel refitted and torqued to spec.
After this, Pete then stripped the faulty washer pump. He found that the mating faces were well worn, where the internal pump cogs rotate against it much like an oil pump. He cleaned and reversed the plate, fabricated a new cork compression gasket as it was missing and sealed the assembly with a liquid gasket. He then re assembled the unit and put it back into the engine bay, tested it and there is now a much quieter operation, and a lovely clean windscreen!
