561design

While I was powdercoating the calipers, one of the rubber bushings I was using to seal the lines fell off and emptied the whole system. The brake reservoir was empty.

We bench bled the master cylinder and checked it to see if it's working. It's good.

We tried to bleed the system by using a vacuum pump, that didn't work. We tried the two man pumping method, no good. Last night, we tried the pressure pump method and ran about 1.5 bottles thru each caliper. While some bubbles came out, the pedal is still very soft.

Should something be plugged to the car to turn the ABS on? Am I missing something? I'm at a loss.

The next thing I'm thinking of doing is to put speed bleeders on and bleed all four calipers at the same time.

deadlyvt

I'm just assuming you're doing the caliber bleeding in the right order... Farthest first closest last... What fluid did you use I'm assuming new fluid and either the factory Benz or something even higher quality?

561design

Yes, furthest caliper and ending with closest. Using similar quality OEM dot 4.

BLKROKT

I think if you drain the entire system like you did, you need to use the MB STAR tool to actuate the ABS pumps while refilling/bleeding. Not 100%, but that's what I've heard.

561design

That's what I thought as well. I couldn't find anything in regards to that when I searched.

Velociabstract

I had a similar problem after rebuilding my front calipers. The master cylinder and one line emptied. I put a gallon of fluid through the system and still had a soft pedal. What finally solved my problem was taking out my new brake pads, using worn pads, then bleeding.

Les

Jasonoff

I have heard you can simulate what the star system does with the ABS pumps by slowly pumping the brake pedal while pressure bleeding with the car is running.

561design

Yeah, I think that's the next thing I'm gonna try. Thanks!

BLKROKT

FYI the AutoEnginuity program can actuate the ABS also, and it's a handy tool to have around anyway.

Jons95c36amg

I had my Clk55 brake fluid drained recently. After the new fluid was done. I noticed a mushy feel of the brakes. Went back and they found there was the slightest air(bubbles) in one of the brakes. The bleeding process was a 2 man job. Have them do it again.

wasp01amg

I had a similar problem bleeding the brakes on an F150. Turned out that there was a bleed fitting on the ABS valve. Once I bleed that, all was well.

Diabolis

Pressure bleed at 10-12 psi, with farthest -> closest caliper order. If air did get in the ABS pump, then you do need a s/w tool to open it up.

561design

Thanks!


Yup, did all that. It appears that air did get into the ABS pump. During the install of the calipers a screw had been stripped on the hardline. The guy who came in to cut/flare the hardline didn't cap the line when he was done. So the whole system leaked out over night.


In hindsight, I should have put a rod in the foot well to push the brake pedal down to close the master cylinder and prevent the system from draining out completely.


We're getting the tool into the shop tmrw to open up the ABS pump and hooking up a pressure bleeder @ 30psi to get the damn air out.


Tough lesson learned, but I'll definitely not make this mistake again!

561design

Tried this last night and it didn't work. Getting a tool in the shop tmrw to open up the ABS pump.

Jasonoff

Thanks for confirming.

Gerry_M

This happened on my BMW X5. I tried to make an appointment with the dealer a week later but I found that the pedal got firmer the more I drove it during the week. By the time I took it in, the pedal was already good.

Diabolis

You need the MB STAR Mux or equivalent in order to properly cycle the ABS valves and pump while bleeding the fluid, but I don't think you want to apply more pressure with the pressure bleeder than what you'd normally use. I don't have access to DAS / Xentry at the moment, but the procedure you need to follow is the one you'd do if you were replacing the ABS unit. I don't know what pressurre is calls for (it's entirely possible that it calls for 30 psi), but I wouldn't arbitrarily decide to increase it as too much pressure can permanently damage the master cylinder seals and ABS pump, which are rather pricey. Just a word of caution - I learned it the hard (expensive) way on a P-car...

561design

Hmmm, I read somewhere that 30psi was required. But confirmation would be great. We've been using 30psi and everything seems ok. Maybe we blew the ABS pump and I don't know it yet. We did bench bleed the master cylinder and it is properly functioning.

Jasonoff

IIRC it mentions 2bar in the WIS when using the MB pressure bleeder tool.

Diabolis

In that case 30 psi is perfect (2 bar = 29 psi). Tks Jasonoff.