Changing W140 rear brake hoses - bleed?

[Unavita]

Pretty direct question here that I do not know the answer to.

I changed the rear flex lines. Little fluid dripped out. Can someone post, share or go over the bleed procedure on '95 MY (W140 S420- is my car)?

Bleed entire system? Energize system and bleed ABS as well? Car is ASR equipped.

 

[gerryvz]

With an ABS+ASR system, you have to bleed the pump first at the valve marked "SP", and then the four individual brake lines. For the lines, you first bleed the passenger side rear, then the driver's side rear, then the passenger side front, and lastly the driver's side front.

The procedure for the .036 (E500E) is posted here. The W140 with ASR should be very similar.

42 Brake System

 

[gsxr]

The W140 may have additional procedures required. Follow the FSM directions:

https://www.500eboard.co/misc/Manuals/Servicev3.2/W124/w124CD1/Program/Maintenance/94_95/4280.pdf

 

[Unavita]

Thank you both for the clarification! I am familiar but foggy. Well done!

 

[Unavita]

I've done this job before and now I remember that I essentially had to high pressure bleed at the abs pump and master cylinder ever line. It seems my unit is not similar to the one in the illustration: I do not see a "SP" port. The car is a 1995 S420.

 

[gerryvz]

Looks like you need to find specific instructions for the W140 chassis to bleed it. Given that this forum's focus is generally the E-class, and it seems there are differences between the two, there probably will be little information here.

 

[Unavita]

Okay.

 

[gerryvz]

Try Banzworld or PeachParts. A Google search should point you to relevant threads/posts for the W140.

 

[Unavita]

Yeah- I have been on BW for a while- years before I grew tired of the constant back and forth and not being able to get good information or find the answers that people look for. I didn't know it was a question specific to the W140 and or that the pump PN 0024319612 is exclusive to the W140. The AllData site is lacking as well. But as a hobbyist I was hoping of finding professionals willing to share their expertise with someone desirous of knowing. But I suppose your resposne means you don't know the answer either.

 

[gerryvz]

But I suppose your resposne means you don't know the answer either.

Well, I suppose the focus of this site does tend to be on the W124 (.036 and .034). I have removed many ASR pumps from W140 models of the early-to-mid-1990s, and they are identical to those used in the .036. So personally I would follow the same procedure to bleed brakes.

But, I’ve never owned a W140, so I can’t definitely tell you what to do. Furthermore, since this thread pertains to the W140, and not the W124, it does not belong in the "Brakes Suspension and Steering" sub-forum, so it has been moved to Off-Topic Discussions where it should be.

I’m sorry that this site has not met your expectations. We do our best to try to help, and in this case it appears that it was not good enough. You get what you pay for?

 

[JC220]

Yeah- I have been on BW for a while- years before I grew tired of the constant back and forth and not being able to get good information or find the answers that people look for. I didn't know it was a question specific to the W140 and or that the pump PN 0024319612 is exclusive to the W140. The AllData site is lacking as well. But as a hobbyist I was hoping of finding professionals willing to share their expertise with someone desirous of knowing. But I suppose your resposne means you don't know the answer either.

Yes you should energise and open the switchover valve to bleed, pin outs described below

DIY Brake Bleeding on W140 With Master Cylider...

www.benzworld.org

I have 3x W140s and will be doing a brake flush / bleed soon and will energise the valve + pressure bleed like any other car.

 

[gerryvz]

Yes you should energise and open the switchover valve to bleed, pin outs described below

DIY Brake Bleeding on W140 With Master Cylider...

www.benzworld.org

I have 3x W140s and will be doing a brake flush / bleed soon and will energise the valve + pressure bleed like any other car.

Perhaps you can create an illustrated HOW-TO for our friend. Heck, maybe we can even create a W140 sub-forum for it !! Because, .034/.036 focus too narrow.

 

[JC220]

Perhaps you can create an illustrated HOW-TO for our friend. Heck, maybe we can even create a W140 sub-forum for it !! Because, .034/.036 focus too narrow.

But then that would require reading Gerry.

Maybe I should just catch a plane and make it happen?

 

[gerryvz]

✈ We'll see you soon?

Seeing as we can't go your direction ...

 

[Unavita]

Okay fellas. I get what you're saying to include the tongue in cheek metaphors. Putting the condescending aside I read that thread. Then I read another... and yet another... each with different "facts". I read the information here posted above. I read the AlldataDIY. One or more saying you do not need to do a full bleed when doing a small job like changing pads and then bleeding brakes. I consider rear flex lines to be the same= small. The question seems unsettled as to weather one needs the SDS just for an annual bleed.
I have done the brakes before on this very car- meaning I changed front flex lines. I did not "energize" in either of the descriptions and do not own an SDS system. However, my brakes worked perfectly. I have READ everything and the only perhaps mis-step is in relieve the pressure at the master cylinder. I bled the exposed nipple that is not attached to a brake line on the master cylinder. (SEE PIC). The two lines coming out of the cylinder are marked "H" and "V" which I understand to mean "front" and "rear" or "hi" and "low".

 

[Unavita]

An illustration would be lovely. Perhaps a caricture as well.

 

[gsxr]

Any time the hydraulic system is opened, i.e. to replace a brake hose or caliper, the entire system must be bled. And some models may require pressure bleeding. The SDS should NOT be required except in special cases, like the early 210 with optional ESP.

What's confusing me is the lack of port SP on an early 140 with ASR. And, the FSM has never been very clear to me about what should be done with the switching valve below the MC, on models which have this. It doesn't look like your 140 has the switching valve on the MC, just the ASR charge pump. But you also have a bleed valve on the MC, which I'm not familiar with. I don't know the 140 well enough to help much on this one.

V/H is Vorderseite / Hinten (approximately), German for Front / Rear.

 

[Unavita]

Any time the hydraulic system is opened, i.e. to replace a brake hose or caliper, the entire system must be bled. And some models may require pressure bleeding. The SDS should NOT be required except in special cases, like the early 210 with optional ESP.

What's confusing me is the lack of port SP on an early 140 with ASR. And, the FSM has never been very clear to me about what should be done with the switching valve below the MC, on models which have this. It doesn't look like your 140 has the switching valve on the MC, just the ASR charge pump. But you also have a bleed valve on the MC, which I'm not familiar with. I don't know the 140 well enough to help much on this one.

V/H is Vorderseite / Hinten (approximately), German for Front / Rear.

That is exactly my conundrum. No SP port. And agreed on the FSM not being clear.

Thanks GSXR for your direct input.

Even this bulletin refers to the SP port!

 

[gsxr]

BTW - your ASR pump looks different than what I'm used to seeing. Can you post your VIN, or the last 6 digits? There are some oddities in the EPC...

 

[Unavita]

I thought so too and then I checked it with the local dealership!

Here ya go though: SA236384

Model ABS pump is 002 431 9612

additionally, the one that looks like all the others is also the one found in my '91 500SL. It has the SP port.

 

[gsxr]

That helps! From what I can tell... you have a weird, 1-year ETS/ASR unit. 1996-up used a different part number. And earlier (1994-ish & previous) used the ABS/ASR unit with the SP port.

Best I can tell, you should try doing a normal pressure bleed, 25-30psi, starting at passenger rear and working the driver front. Only question is if you should energize the solenoid at the MC while bleeding.

 

[LWB250]

Having owned a number of W140s I resorted to vacuum bleeding on several occasions. Say what you like, but it worked for me in more than one instance when I had a malfunctioning EZ-Bleed. Get your siphon cup and a MityVac and have at it.

Dan

 

[gsxr]

Dan, did you vacuum bleed cars with ASR? Or only non-ASR cars?

I thought ASR needed pressure to push through valves inside the ASR unit. That might only apply the earlier "ABS/ASR" units shown in the diagram above though.

 

[gerryvz]

I once had a vacuum bleeder. It was IMHO completely worthless, particularly compared to a pressure bleeder.

I think I'd rather "gravity bleed" a car than vacuum bleed it. Pressure bleeding is 100% the way to go. Just my opinion....

 

[LWB250]

Dan, did you vacuum bleed cars with ASR? Or only non-ASR cars?

I thought ASR needed pressure to push through valves inside the ASR unit. That might only apply the earlier "ABS/ASR" units shown in the diagram above though.

At least one of them had ASR. And say what you want, Gerry, it worked, but yes, it was slow in that I didn't get a lot of fluid out over a short time. Unfortunately, the first time I did it was because the EZBleed I had was leaking, and I didn't have much of a choice. And yes, pressure bleeding is by far the way to go, and I now have a good quality pressure bleeder I use regularly. The EZBleed ended up being a POS and went into the trash.

Crude, but effective.

Dan

 

[Unavita]

Having owned a number of W140s I resorted to vacuum bleeding on several occasions. Say what you like, but it worked for me in more than one instance when I had a malfunctioning EZ-Bleed. Get your siphon cup and a MityVac and have at it.

Dan

Dan, that is exactly what I did last time. I believe you are referring to connecting the miti-vac at each bleeder valve at each wheel and use vacuum to 25psi, correct?

 

[Unavita]

That helps! From what I can tell... you have a weird, 1-year ETS/ASR unit. 1996-up used a different part number. And earlier (1994-ish & previous) used the ABS/ASR unit with the SP port.

Best I can tell, you should try doing a normal pressure bleed, 25-30psi, starting at passenger rear and working the driver front. Only question is if you should energize the solenoid at the MC while bleeding.

View attachment 112656

THAT IS EXACTLY THE QUESTION!
So- I followed the procedure... twice so...
Energize- that's the question. One source said to use a stand alone 12v source and flat pin here and ...disconnect the 28 fuse... That or vacuum at each wheel seems to be the answer... well one I will try today.

 

[Unavita]

Welp- to quote Doc Holiday "I have two guns. One for each of ya." (

) < if that's allowed> I have a dual miti-vac and a pressure one only so I could suck and blow at the same time.

 

[LWB250]

Dan, that is exactly what I did last time. I believe you are referring to connecting the miti-vac at each bleeder valve at each wheel and use vacuum to 25psi, correct?

Correct.

 

[Unavita]

Welp- I believe I completed the task. No SDS or icarsoft/ dealer. I am composing a write up. I suspect as GSXR figured out this is a one year (1995) ABS/ASR unit that is CLEARLY different than those that preceded and succeeded it. WRITE UP TO COME.

 

[Unavita]

Brake bleeding a 1995 W140 S420

Today I have driven my 1995 W140 S420 20 miles. There are no dash lights and the brakes are working perfectly. This post is to answer those that have the exact same year car with the ABS/ASR pump number 0024319612. This part was succeeded by 0024319812 and is said to be the same. I can not verify that.
WHAT IS IMPORTANT TO NOTE IS that this model is the ONLY one that I know of that DOES NOT have an SP port. This is important because every factory manual and direction for the ASR models refers to this port in it’s procedure.

I WILL be covering here how to bleed the brake system. NOTE: I have not used an Star Diagnostic Tool or similar device to “actuate y61 switch other valve”.


THIS FIRST ACCOUNT DID NOT DO THE JOB! It left me with a stuck caliper at the front passenger and rear driver. In this I followed the procedure found in the EPC WIS, on AlldataDIY and on this thread and site. Of course the only difference being there is no SP port to relieve pressure from. This was done after replacing the rear brake flexible lines and the front calipers, pads and hardware.

(When up capping a brake line I used rubber plugs from my Miti-vac kit to stop brake fluid from leaking and air getting in the system.) After topping off with Pentosin Super Dot 4 I opened the male nipple on the master cylinder. I started the car. The I brought the mitt-vac pressure bleeder that I attached to the fluid reservoir with their provided screw on cap style attachment. I squeezed the handle until the psi was 20 and made sure all air bubbles were gone before I stopped this process. I then moved to the passenger rear.
At the this tire I had my assistant keep pressure with the mitt-vac to 2 PSI. I bled that wheel until there we no air bubbles. I did this procedure then for the driver rear, front passenger and then front driver. At the end of this process the aforementioned problems arose- the front passenger and rear driver caliper was stuck closed.
With the car running I put it in gear. I wanted to see if the driver rear would turn. I gave it gas. The ABS pump began making noise that it makes similar to when a person slams on the brakes. The dash board lit up with the ABS ASR and Brake light indicators illuminating.

That evening I posted in this forum. I searched through engines and posted in Benzworld. After searching for two days I was still no closer to answers. Then I came back to the 500e board and saw some additional posts. GSXR figured out that the unit on this singular model year is unique to it. Another member posted his experience and it was similar to mine when I had done this job once in the past.

The following is what I did. THIS WORKED.

The beginning of my process was identical to the above until I got to the passenger rear.
THERE WAS A BIG CHANGE HERE! I attached the pressure bleeder to the fluid reservoir. BUT THIS TIME I attempted to also use a second vacuum mitt-vac at the wheel. I WAS NOT GETTING MUCH FLUID AT ALL!
(THIS NEXT PART I DO NOT RECOMMEND UNLESS you have a new or close to new master cylinder). I removed the pressure bleeder from the fluid reservoir, filled the fluid and put the oem cap on it. I then asked my assistant to pump the brakes as should would if she was coming to a stop. She did this for 9 times. I still was trying to pull with the vac at the wheel but it was creating air bubbles. Finally I had her pump 9 times and then I closed the valve. HERE IS THE PART THAT WORKS:
AFTER PUMPING FOR 9 TIMES I HAD HER PRESS THE BRAKE ALL THE WAY TO THE FLOOR AND once she was at the floor I opened the bleeder valve with the 9mm brake line wrench and closed it as soon as the fluid was without bubbles. It was a very quick open - close action. I repeated this two more times. I then did this at each wheel. The passenger front required the most attempts. THE ENGINE WAS RUNNING DURING THIS ENTIRE PROCESS and I MADE SURE I DID NOT GO LOW ON FLUID in the reservoir.

MY BRAKES feel better than they ever have. I have had no lamps come on. I hope this helps!

FOOTNOTE: when my assistant was pressing the brake to the floor it was done so gently. We did hear the metallic click of the master cylinder until- this stopped once all wheels had been done to completion.

 

[Unavita]

So we are day 3 and the brakes have had no inkling of problems. The car, with new calipers, new Pirelli P-Zero's, New complete tune up, new trans filter and fluid change, new front sway bar links makes a person realize what a bombshell these cars were when they came out. I have not "hard braked" the car yet. Will do soon.

 

[Unavita]

5th day. All is perfect. I will post again here only if something goes wrong. I hope this helps some other poor soul!