Brakes: Gravity vs Pressure Bleed

sikwan

06 T1N Can
I'm about to embark (plan) on flushing my brake fluid and doing a disk/pad inspection. I haven't located the fluid yet, but would like to try Gravity bleeding or maybe I should call that flushing.

Has anyone tried it on the Sprinter and how long did it take?

Is the procedure the same as pressure bleeding (start at brake farthest from master cylinder, fill master occasionally) or can you gravity bleed with all four bleeder screws open?

I may just do the regular/pump action/pressure bleed if it's going to take forever or if it's not possible.

Thanks!
 

rlent

New member
In order to fully flush the brake system fluid the use of a DRBIII is required (on T1N's), in order to (repeatedly) activate to activate something in the ABS (either a pump or valving) I believe.

I just had this done at the dealer ..... the price was $94 (1 hour) plus the cost of the fluid (around $20 I think) ..... having bleed brakes before a number of times, I considered it a very reasonable price.

I also had them do a cooling system flush and replace the anti-freeze, price was about the same as the brakes. Again, a reasonable price IMHO.
 

sikwan

06 T1N Can
Thanks for the reply, RLent.

In order to fully flush the brake system fluid the use of a DRBIII is required (on T1N's), in order to (repeatedly) activate to activate something in the ABS (either a pump or valving) I believe.
Service manual says you don't need the DRBIII. :idunno:

It actually doesn't state that, but it goes on to say (on an overhaul) to open all bleed screws and close when you see fluid dripping. Then go through the normal "have helper push down brake pedal" while releasing each bleed screw one at a time.

It also said DOT4, but I think read somewhere here and on the master cylinder to use DOT4+. :hmmm:
 

mobileoilchange

New member
pressure bleeding is when you use a adapter cap that screws onto the master cylinder in place of the yellow cap. you then use a pressure bleeder that is either pressurized by a hand pump (think of a weed sprayer) or a pressure tank thats pressurized by a air compressor. once the master cylinder adapter cap is on and the hand pump or air tank is pressurized you can then open the right rear bleeder until the fluid is clean, then close the bleeder screw and go to the left rear bleeder, close the bleeder and go to the right front and then the left front. but you must keep on eye on the fluid level in the master cylinder. it must keep full, if you get air in the brake system you must then bleed it for air.

another way of flushing or bleeding brakes and fluid is by vacuum. again starting from the r/r, l/r, r/f, l/f keep the vacuum going until the fluid is clean.

the best way to remove air from a brake system is by reverse fluid injection (RFI) since air rises its best to remove it by pushing the new fluid from the bleeder to the master cylinder.

go to this site and it will describe everything to you. http://v-12.com/technical.htm

master cylinder caps. http://www.powerprobe.com/powerprobe/BBAdapters.html

hand bleeder / flusher. http://www.mityvac.com/pages/products_hvpo.asp

hand pump.http://store.motiveproducts.com/sha...reType=BtoC&Count1=304699122&Count2=221839547

air powered bleeder/flusher. http://www.mityvac.com/pages/products_bcbe.asp or
http://www.branick.com/core/products_brake_bleeder.php


i myself use the power probe caps with both the phoenix power ject or the branick bleeder/flusher. but for personal use i think the motive products is good.
 

rlent

New member
Thanks for the reply, RLent.
You're welcome, of course.

Service manual says you don't need the DRBIII. :idunno: It actually doesn't state that,
You're right - it doesn't :D:

but it goes on to say (on an overhaul) to open all bleed screws and close when you see fluid dripping. Then go through the normal "have helper push down brake pedal" while releasing each bleed screw one at a time.
Ahhh .... bleeding ..... and I thought you wanted to flush it ..... :smirk:

The definitive source:

Brake Fluid Flushing heads up
 

rlent

New member
BTW, I have a friend who has an older Sprinter (2003 3500 IIRC) ...... he'd never had the fluid flushed .... was talking to him about a month ago ....... his ABS unit had recently failed. My recall isn't perfect but it seems like he said that the price for a new ABS unit was either $1800 or $2100 .....

Dunno .... might be the cheapest $120 ya ever spend to have the dealer do it right .....

(BTW, apparently he was told by the dealer wrench that if the ABS unit fails, the hydraulic brake system is still functional - you just don't have ABS brakes - I have no idea whether that is actually true or not)
 

mobileoilchange

New member
the reason why you should flush brake fluid every 2 years is because brake fluid assorbs moisture and causes internal brake rust and fluid boiling.

(BTW, apparently he was told by the dealer wrench that if the ABS unit fails, the hydraulic brake system is still functional - you just don't have ABS brakes - I have no idea whether that is actually true or not)

this is true, also since i didnt see his abs unit, it could of failed do to internal rust from moisture in the fluid.
 

rlent

New member
the reason why you should flush brake fluid every 2 years is because brake fluid assorbs moisture and causes internal brake rust and fluid boiling.
Yup.

also since i didnt see his abs unit, it could of failed do to internal rust from moisture in the fluid.
If I recall some of he comments by Doktor A the gist was that there are very small passages and orifices and the like inside the ABS unit which can be very easily clogged or plugged ..... course I could be confusing that with something he said about the NAG1 valvebody ....... :crazy:
 

abittenbinder

Doktor A (864-623-9110)
Proper Sprinter brake fluid flushing (to exchange moisture laden fluid) or brake bleeding (to eliminate trapped air due to component replacement) requires remote ABS activation(stationary vehicle)with a DRBIII.

The prompted DRB program requires 2 techs and activates the ABS pump and opens appropriate bypass valve solenoids remotely. This is the only way to purge the ENTIRE brake system of aged fluid or of entrained air, whichever your intent.

Sprinters without ESP (pre-'04 2500 and some 3500) will need the ALB lever temporarily secured to the full load position to prevent pressure spikes during bleeding/flushing.

BTW, the ABS pump activation is NOT done to solely pressurize lines for bleeding. The procedure requires an appropriate generic pressure bleeder with the appropriate German ATE sized cap adapter to provide the majority of the fluid expulsion.

You can use a pressure flushing/bleeding device without the DRBIII, that's better than doing nothing, but that will allow the most expensive components of your braking system to remain exposed to contaminated fluid (or air, if the ABS unit was serviced).

Plan on using a minimum of 2 liters of DOT +4 fluid. Doktor A
 
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Altered Sprinter

Happy Little Vegemite
Thus AD8-AD9-animation.gif for BFDV
Richard
 

TimJuhl

Member
Guys,
After reading the previous posts I picked up my phone and called the nearest sprinter dealer (70 miles) and asked about getting a brake fluid flush. He confirmed that it was recommended every two years and quoted a price of $120. Inasmuch as my basic 36K warranty runs out in a few hundred miles I decided to go ahead and at the same time have them give it a once over looking for anything that needs attention. I'm planning on taking a long trip with the Sprinter in Feb/March so I thought it was a good time to "git -) done." Dr. A's comments about the need to use a DRBIII showed me the wisdom of not trying it myself.

Had it not been for this forum I would have been ignorant of the need to flush the brakes. Looking in my owners manual and in the obvious places in the service manual I downloaded from this group I do not find any mention of flushing the fluid other than the admonition to "Only use brake fluids approved by the manufacturer (DOT 4 plus)."

I appreciate the information that this forum presents as it allows me to be an informed Sprinter operator. As Kelli Bundy said, "To be forewarned is to have four arms....." :)

Tim

Note: If you are scratching your head about my quotation, she was a character on the old Married with Children TV show.
 

sikwan

06 T1N Can
Well, I just spent $123.57, no tax, free ship, for the Mityvac MV6835...

MV6835.jpg

I have a few vehicles that I have to flush/bleed, so hopefully this will pay for itself (convenience-wise) in the long term.
 

jdcaples

Not Suitable w/220v Gen
I can't wait to see your write up, Sikwan.
 

amauri

New member
Well, I just spent $123.57, no tax, free ship, for the MV6835...

View attachment 11332

I have a few vehicles that I have to flush/bleed, so hopefully this will pay for itself (convenience-wise) in the long term.
We use these bleeder pumps all the time and have found them to be effective.
But, because of the design of the bleeder screw, you loose quite a bit of the suction thru the bleeder threads.

Looking at the photo bellow, you can see that much of the suction will be lost through the threads instead of sucking brake fluid from the caliper.

I take the bleeder off the caliper and wrap some PTFE tape on the threads before screwing it back in, just don't tape the two side ports just bellow the threads.

The bleeder in the photo is from one of out bikes and smaller than those used on the Sprinter calipers but you get the idea.
 

Attachments

sikwan

06 T1N Can
Thanks Amauri. I read about the vacuum leakage through the threads, but was going to do a wait and see. Some teflon tape will be on my list to get.
 

amauri

New member
I just installed new pads, rotors and front wheel bearings on my 05-158.
For brake fluid, I used Motul 5.1.
The dry/wet boiling temps exceeds the MB requirements and the Motul has the thinner viscosity intended for ABS systems.

Started by sucking most of the fluid out of the m/c reservoir using the vacuum pump hose thru the reservoir cap.
Next I unbolted all four calipers, lifted them off the spindles and secured them with heavy wire to keep them from dangling and damaging the brake hose.
Cracked open the bleeder screw and retracted the pistons on one caliper at a time to push out as much of the fluid as possible.
Since there was still quite a bit of old fluid in the plastic m/c reservoir, I removed it to dump out the rest. After removing the single screw that holds it in place I wiggled it around a bit to loosen it from the rubber grommets (didn't want to break it).

Now that the system was as empty as I could get it, I filled the reservoir and pumped it back up and had a firm pedal without having to bleed anything.
The final step is to find a shop that has a DRBIII and knows how to cycle the ABS to flush out the last bit of old fluid from the system.
.
 
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elvisvoltare

New member
Proper Sprinter brake fluid flushing (to exchange moisture laden fluid) or brake bleeding (to eliminate trapped air due to component replacement) requires remote ABS activation(stationary vehicle)with a DRBIII.

The prompted DRB program requires 2 techs and activates the ABS pump and opens appropriate bypass valve solenoids remotely. This is the only way to purge the ENTIRE brake system of aged fluid or of entrained air, whichever your intent.

Sprinters without ESP (pre-'04 2500 and some 3500) will need the ALB lever temporarily secured to the full load position to prevent pressure spikes during bleeding/flushing.

BTW, the ABS pump activation is NOT done to solely pressurize lines for bleeding. The procedure requires an appropriate generic pressure bleeder with the appropriate German ATE sized cap adapter to provide the majority of the fluid expulsion.

You can use a pressure flushing/bleeding device without the DRBIII, that's better than doing nothing, but that will allow the most expensive components of your braking system to remain exposed to contaminated fluid (or air, if the ABS unit was serviced).

Plan on using a minimum of 2 liters of DOT +4 fluid. Doktor A
I want to follow your advice and have my brake system flushed to protect these components on my 2002 sprinter. So, I called my local Mercedes dealer and explained the service I wanted. They claimed that they could do a standard flush for $160, but when I pressed them to insure that this would inlcude the flushing of the ABS by using a remote activated device, the technician acted like he didn't know what I was talking about and said the pumped flush was all they ever do. Any ideas where I could get this service done? I'm in the Las Vegas area.
 

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