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Gentlemen:

A friend of mine will be installing a new master cylinder (MC) in his MB and he asked for some help. I seem to recall a post about pre-filling the master cylinder with brake fluid, before installing it. If this is correct, can you tell me how.

Also, while we are replacing the MC can we replace the old DOT3 with synthetic DOT3.

Regards Dennis

It's called bench bleeding and most new master cylinders come those directions and the rubber hoses to do it. You place the master cylinder in a bench vise. Connect a hose to the pressure port and put the other end of the hose in the reservoir. Add fluid and pump the shaft until the bubbles stop. Then mount the cylinder with the hose still in place. Then quickly disconnect the hose and install the fittings and pressure tube.

Dot 3 is compatible with all DOT 3 & 4 fluids and is not compatible with DOT 5 fluids.

Thanks Wes for the info. Best Regards Dennis