Matt,
it's the intermittent sponginess that I don't like. so yea as you said, bleed it anyways to be on the safe side.
good luck and keep us updated.

Update
 

Got around to re-bleeding the brakes
yesterday. Followed the sequence from
RR to RL to FR...no bubbles came out.

Pressure on Motive Bleeder approx.
20-22psi. ( I found the E-Class Owner's
bible indicates that it is safe to pump
up to 30 psi...not sure if anyone has
tried that)

Started the LF and I get nothing for
first 2 minutes i.e. no bubbles in the
fluid....Then suddenly I start seeing
a stream of bubbles....I was a little surprised as I had on the last bleeding
pumped out 1.5 pints without a bubble.

Anyway, I noticed that the bubbles were getting introduced by the bleeder valve itself. If apply finger pressure to the side of the bleeder valve the bubbles vanished. So the current theory is that the caliper bleeder valve once it is cracked open is letting some amount of air back EVEN though there is pressure applied through the motive bleeder....

Later in the summer I will buy a set of those speed bleeders and re-try.

As far as the pedal condition goes, the pedal is somewhat less mushy. Braking action is fine so I will live with it....

After two sets of bleeding I am sure about one thing....I must have the cleanest brake fluid in my brake lines
since my '92 400E rolled off the assembly line.

Thanks for the helpful advice folks! Much appreciated.

400E_FAN, with the system pressurized it doesn't make sense that air is leaking into the system through the bleeder fittings; however, a member of another forum recommends removing the bleeder fittings before starting to bleed the system and coating the threads with silicone grease or Krytox.

Any chance of contamination?
 

Fred,

Any chance that silicone grease or Krytox mixing with brake fluid is detrimental to the system? Sounds like a cheaper way to go than the speed bleeders...

Matt, I guess there's a chance of contaminating the brake fluid if you put gobs of silicone grease or Krytox on the bleeder fittings; however, if you apply it sparingly there should be no problem. Keep in mind that the power bleeder pressurizes the system. Any brake fluid that leaks past the threads will 'flush' the threads.

Yeah, I believe you are 'pressure' bleeding with that Motive device, not vacuum bleeding. No air should be coming in from the bleeder threads. If anything, fluid would be leaking out

I have the vacuum type ('Vacula', also sold as 'Shark'). I find that putting teflon tape on the bleeder threads works better than silicone grease. The air that comes in around bleeder with vacuum bleeding is not harmful, but you cannot tell when you have gotten all of the air out of the system.

how about having someone else just help you out to pedal the brakes while they're bled ? wouldnt that solve this particular problem ?

Re-try
 

csnow, fredman

I will try teflon tape on a couple of bleeders and silicon grease on a couple to see what works the best ...but later in July.

Benz300,

I just did not have anyone around
that could pump the pedal while I was attempting the latest bleed....was really early on last Saturday morning. But will try and see if that can be engineered next time.

Thanks again gents.

Are these new calipers up front ? I hope not rebuilt. Used OK if it's not bad.
You should tap with a rubber mallet the calipers as you bleed them to release any bubbles in the caliper.

Also, if your brake-lines are over 3-years old, I would replace them as well.

Do you have ASR ? If so, do you bleed the ASR/ABS pump ?

If you do a "pump" the brake pedal type of bleed, I would be hesistant to push the pedal all the way down, because any corrosion that may have built up since we normally don't use the ENTIRE pedal stroke may make nick the master-cylinder's seal.

I would stick with a power-pressure bleed.

:-) neil
1988 E36T AMG
1993 500E

Calipers are re-builts/ New hose lines
 

ke6dcj,

Front calipers are re-built with new PBR Deluxe pads....did not want to spring for new ones at all given the cost. New hoses for both calipers also went in.
Rear Calipers are about a year old, again rebuilts installed a year ago with textar pads & new hoses then. No problems with them in approx. 12K miles.

Have not bled the ASR/ABS unit....I have heard mixed opinions on whether that is necessary or not....But I may do that too next time again later in July.

Update
 

I got around to taking a stab at this again. I rebled the front two calipers using the pressure bleeder and with some teflon tape on the bleeders. Looks like problem is solved. Somehow air was getting drawn in with the bleeders...and the teflon tape did the trick...Pedal feel is fine and master cylinder is healthy. Thank you for all of the advice and tips; much appreciated!