Motive power brake bleeder not usable on W124 (1987 300D)?
 

After replacing the rear calipers, I purchased a Motive power brake bleeder in order to flush the brake system completely. unless I'm missing something, it looks like there are some vents covered by rubber plugs in the brake reservoir...I'm guessing that pressure bleeding is not going to work without plugging those vents somehow. I was trying to do this job today without a helper to get back on the road, but that does not look like it's happening.

I bled the brakes the old school way with a buddy pumping the brakes a few months back, but the pedal is still very soft (It'll stop with a bit of pumping, but it's not really drivable as-is), so I'm guessing there is air somewhere, probably in the "new" rebuilt calipers.

Any tips or tricks on bleeding the brakes? It seems like the old school method was not too terribly effective on this car the first time around.

I have also noticed a honking type sound coming from the area of the master cylinder when pumping the brakes. I'm starting to wonder if the MC might be on the way out. I'll take a video in a bit.

If the vents leak fluid when using the bleeder, they need new caps.

Thanks -- ordered the caps, the current ones are badly cracked. Here are the videos of the sound, It's audible with the engine off, with the engine running, it does not make the honking sound.

Not running:
https://www.youtube.com/watch?v=flhubS0a8e8

Running:
https://www:.youtube.com/watch?v=F7COc9KqLKA

The shop I had install new rubber brake hoses on my W124 300D used a Motive power bleeder, so it should work?

Sorry, no details on method, was not paying attention as I was chatting with the shop owners. But the techs doing the job did not look like they had any problems.

I have found the one man bleeder method works great, never got air issues later.

Good to know -- I had never seen that method until yesterday when I was poking around on youtube, and it looks like a really simple way to do it. I saw someone with the tubing in a half full bottle, but I'm guessing a long loop of tubing higher than the bleeder would work just as well.

I'll probably just do the dry method with the power bleeder once I have the caps in hand from pelican. If the caps don't hold 5psi or so of pressure, I'll try the one man pump method.

The caps came in and the power bleeder worked without any trouble. Once bleed valve was clogged and needed to be cleared by pumping the brake pedal to get enough pressure to dislodge what appeared to be a bunch of rust flakes. Who knows how long that fluid has been in there, well over a decade, I'm sure.

It's all clean now, and the pedal is nice and firm without replacing the master cylinder. There was a lot of air in the system.

Blow in the pic is how I vacuum bleed the brakes on all of my vehicles.