A few years ago the clutch began to drag on my '88 190E 2.6, and I suspected the slave cylinder was bad, and I was right, but the failure mode was really surprising. The pushrod was worn and mushroomed over on the end. I've religiously changed brake fluid every two years, and the inside of the slave was perfect. I bought a new slave from Peach, which was only about 40 bucks and the cylinder casting had the same cast-in number as the original.

The clutch is easy to bleed during a fluid flush, but I was concerned how to fill it when empty. It was in the Haynes 190 manual that I read about this procedure to fill the clutch system from the brake caliper. Prior to doing the slave change I flushed the brake system, so it was full of fresh fluid.

There was a little fluid seepage from the caliper and slave bleeders, but since the fluid pressure is zero or postive as you depress the brake pedal, air won't get into the system, or if it does, it will migrate up. You only need to open the slave bleedeer about half a turn.

I gave the brake pedal about 10-12 pumps with a helper running the bleed valve, then tighten the slave valve and the clutch felt normal. To finish the job I bled the caliper a few more pumps and was done.

The procedure worked like a charm!

When flushing the brakes you have to be very careful to avoid draining the rear reservoir. You can really only see the level from the from the inside (engine side) of the reservoir at the very rear of the reservoir, and when you fill the reservoir, it's best to wiggle it side to side to be sure fluid spills over the baffle to fill the rear, which you can then visually check as above.

Duke