Bleeding W126 brakes with a Motive Power Bleeder

I recently changed the flexible brake hoses in my 1986 300SE.   I wasn’t sure how old they were and they are a wear item.  The next step was obviously bleeding the brakes.  Bleeding W126 brakes is really no different to any other car.    I recently purchased a Motive Power Bleeder to make this job easier.

I’ve bled brakes many ways over the years.   The traditional two person method of pumping the pedal; various one man systems such as vacuum pumps or valves.    So far I had found the vacuum pump system the best.  However I had ruined two vacuum pumps by getting brake fluid in them.    The Motive Power Bleeder looked promising.

At first, it looked like it was going to be much harder than the videos suggested.  I couldn’t get the system to hold pressure.   There was a hissing sound, and it appeared that it was coming from the cap.   I tried to bleed the brakes anyway, and got one wheel done before fluid started gushing out of the reservoir.

Turns out the little rubber grommets above the fluid level sensor had gotten hard and were letting fluid through.   They were still available and quite cheap.   The reservoirs were also still available, an updated version without the grommets.  I got both, as I didn’t want to find the grommets didn’t fix the problem and have to wait another couple of weeks to get the reservoir.   Also in my mind was having a spare reservoir on hand given how little interest Mercedes-Benz has these days on suppling youngtimer parts. The picture above shows the reservoir with the grommets removed, and below shows with the new ones installed.

Once I had the leak fixed, Bleeding W126 brakes with the Motive Power bleeder was a cinch.   It took longer to get the car up in the air and take the wheels off.

I needn’t have put that old tee shirt around the reservoir to catch any overflow, as the new grommets did their job.   There was enough vacuum to do all four wheels.   This may not be the case if starting from scratch, as I had done one wheel last time.

Instead of buying the motive catch cans, I used an old coke bottle with a hole drilled in the lid.   It worked quite well. I drilled hole in an oval shape so it held the hose but let air get into the bottle.

Due to COVID lockdown, I didn’t get a chance to test drive the car.  The pedal felt firm so I am confident that all is well.    I also noticed that I have a miss matched set of wheels on the car, so I want to change some of the tyres so I have a set that match on this car and a set that match as my spare set.

Now I have the Motive power bleeder, I will probably do regular fluid flushes myself.  I don’t think I’ll be that keen to take on the replacement of the hoses though.