Brake bleeding sequence 6R

Chat about your 6R/6C model Polos here!
Post Reply
cheba
Silver Member
Posts: 257
Joined: Sun Apr 05, 2015 1:38 pm
Drives: Polo R WRC 2014
Location: Sweden

Brake bleeding sequence 6R

Post by cheba »

So I'm changing my brake fluid, but I'm a bit confused about the bleeding order. The car is LHD so it has the brake fluid reservoir on the left side and the ABS unit on the right side.

The VW workshop manual states that the correct order is

1. Rear left
2. Front left
3. Front right
4. Rear right

However it doesn't state whether this is for LHD or RHD. Is this correct for my car?

Also I found it strange that the sequence doesn't include bleeding both rear brakes before the front ones (farthest brakes bled first). This is the classic way that I am used to. I tried to google for forum posts discussing brake bleeding on the Polo 6R specifically, and there too it is states that rear brakes should be bled first. So are these people simply doing it wrong?
User avatar
iichel
Bling Bling Diamond Member
Posts: 6361
Joined: Fri Nov 14, 2014 2:14 pm
Drives: Polo 6R 2.0 TDI, Passat B8 2.0 TSI
Location: http://mypassat.nl/

Re: Brake bleeding sequence 6R

Post by iichel »

I think the VW method uses the ABS unit to bleed itself with a diagnostic tool, using the pressure of the ABS pump itself rather than external pressure/suction.
Maybe that makes a difference.

Either way, I'd stick to the VW guidelines but that's just me.
cheba
Silver Member
Posts: 257
Joined: Sun Apr 05, 2015 1:38 pm
Drives: Polo R WRC 2014
Location: Sweden

Re: Brake bleeding sequence 6R

Post by cheba »

iichel wrote: Thu May 10, 2018 10:31 am I think the VW method uses the ABS unit to bleed itself with a diagnostic tool, using the pressure of the ABS pump itself rather than external pressure/suction.
Maybe that makes a difference.

Either way, I'd stick to the VW guidelines but that's just me.
In fact, the VW workshop manual states that there are 3 different stages (https://workshop-manuals.com/volkswagen ... v.a.g1869/):

-Pre-bleeding (using a pressure bleeder to bleed both front brakes simultaneously, then both rear brakes simultaneously, then bleeding again while running the ABS pump)
-Normal bleeding (using pressure bleeder, bleed brakes in the order RL, FL, FR, RR)
-Subsequent bleeding (old school method with one guy pressing the brake pedal while the other opens and closes the bleed nipple, in the order RL, FL, FR, RR)

So the RL, FR, FR, RR sequence actually refers to bleeding using externally applied pressure (pressure bleeder or pressed brake pedal).

I will use a pressure bleeder and will be doing only the normal bleeding. I don't have VCDS so I won't do the pre-bleeding. Of course it is preferrable to do it, but the most important is that most of the fluid in the brake lines is changed. And I don't see why the subsequent bleeding would be needed unless the normal bleeding har failed for some reason.
User avatar
iichel
Bling Bling Diamond Member
Posts: 6361
Joined: Fri Nov 14, 2014 2:14 pm
Drives: Polo 6R 2.0 TDI, Passat B8 2.0 TSI
Location: http://mypassat.nl/

Re: Brake bleeding sequence 6R

Post by iichel »

Ah I see. I currently don't have access to ELSA but the workshop manuals is a direct copy.
Whenever I did work to the brakes, I used a Gunson Eezibleed and used the VW sequence without any issues. No spungy brakes or anything :mrgreen:
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Brake bleeding sequence 6R

Post by RUM4MO »

I agree with you on the logical order to bleed these brakes, ie longest pipes first so in a few months time that will be how I replace the brake fluid on my wife's August 2015 Polo.

I have replaced the brake fluid on my 2011 Audi S4 twice using the Haynes advised order of bleeding and never did anything with the ABS block, I think operating the ABS pump in pulses is required if you accidentally let air into the system - in other words if you did not keep fluid in the reservoir while bleeding/replacing the fluid.

I wonder of some of these changes have been brought on by newer VW Group workshop tools and time allowed for these tasks to be completed, so they work on one side of the car at a time?

From Haynes repair manual for 6R Polo:- LHD cars order of bleeding - LF, RF, LR, RR. for RHD cars order of bleeding - RF, LF, RR, LR if system has been run dry ie emptied, bleed fronts both side simultaneously then repeat from both rears.

Again from Haynes this time for B8 S4:- assuming this is for RHD cars order of bleeding - LF, RF, LR, RR.

So, there you go, Haynes advises bleeding the short lines first.

One maybe just logistical comment I'd make here is, by following the Haynes order of bleeding, and using a DIY type of pressure bleeder like Gunsons EasyBleed, if you clear the remainder of the old fluid from the reservoir with the first line bleeding,then that job can be completed without refilling the fluid containers - which is a good thing, so if my memory serves me correctly, you then only need to refill your fluid containers after completing the front brakes, and the refill is enough to let you flush just the longer rear lines and callipers - if that makes any sense?

Edit:- technically the plan is to get rid of all the old fluid and replace with new, so the Haynes method makes good sense to me, now if I had opened up one of the brake lines for repair, I would bleed that circuit short line first then long line. I seem to have a VW advised amount of fluid to be collected from each wheel somewhere - though that should include a large amount for the first line to be bled as it includes fluid that existed in the reservoir, more than 1 litre for the S4, so hopefully slightly less than 1 litre for the Polo. Two containers of VW Group Dot 4 currently being stored in a warm place ready for action!
cheba
Silver Member
Posts: 257
Joined: Sun Apr 05, 2015 1:38 pm
Drives: Polo R WRC 2014
Location: Sweden

Re: Brake bleeding sequence 6R

Post by cheba »

Well, that is a third way of doing it then (shortest lines first, instead of the classic longest lines first that I've been taught).

I can't really see why it would make much of a difference really. What you need to achieve when bleeding the first line is to flow trough the volume of fluid in that brake line and caliper + the volume of old fluid left in the reservoir. But regardless of which line you bleed first, you need to flow through the volume of old fluid left in the reservoir only once. So in the end it the amount of fluid you need to bleed through the car is the same anyway.

I have a manual so I will bleed the clutch also. Some say that it must be bled before the brakes, some say it should absolutely be done last. I guess it has the shortest line of all.

There seems to be so many ways to do it. Short lines first, longest line first, or the VW method (I'm leaning towards the VW method). And clutch first or last? So confusing.

I think the point of running the ABS while bleeding is to get the old fluid inside the ABS unit out into the brake line so it can be bled out, and getting new fluid into the ABS unit. Without running the ABS pump, you will still have a little bit of old fluid which will be pumped into the brake line the next time ABS kicks in.
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Brake bleeding sequence 6R

Post by RUM4MO »

Clutch, yes, hum, well I've never ever changed the clutch fluid and I've owned cars with combined brake and clutch reservoirs for almost 30 years, I know that I should, but the safety aspect of water in fluid is not an issue with the small clutch system, still maybe desirable to have low moisture in clutch systems even if their cylinders are plastic and don't pose a corrosion issue.

One thing to remember is, it is only too easy to crack a plastic clutch slave cylinder by using too much force when closing the bleed valve.

ABS module, I'm not convinced that it actually has an area where static fluid is stored only to get used when the ABS is operating, what I thought was, when wheel slip or any other situation which requires ABS action, the valves are all closed and a high pressure pump run and the output valves pulsed, so okay, if there is a small volume of old fluid in there, it will get mixed with the new fluid but probably in the ratio of 20:1 so very little impact on the moisture content of the fluid - and if you are replacing the fluid every 2 years from now on things should be okay.

Finally clutch fluid replacing, I don't know about the VW Group workshop manuals, but surely if it is an important operate, it should be included in any task involving replacing the brake fluid, Haynes workshop manual, which is not the motorist's bible, does not mention anything about replacing the clutch fluid while discussing and carrying out a fluid change on the brakes!
cheba
Silver Member
Posts: 257
Joined: Sun Apr 05, 2015 1:38 pm
Drives: Polo R WRC 2014
Location: Sweden

Re: Brake bleeding sequence 6R

Post by cheba »

So I just got back from my local DYI garage where I rented a four point lift.

I ended up doing it in the order specified by the VW workshop manual (RL, FL, FR, RR). I started with sucking out the old fluid with a syringe down to the "min" marking (it's impossible to see through the reservoir so I had to look down at the fluid level in the reservoir, then look at the "min" marking on the outside of the reservoir, and trust my 3D vision). Then I filled it up with new fluid almost to the "max" marking, connected my newly purchased bleeder (Sealey VS820) containing the new fluid, pressurized it and started bleeding.

For the first caliper (rear left) I had to bleed through a lot of fluid to get all the bubbles out. Even after the new, clearer fluid was coming through, bubbles were still coming. After about 0.45 liters bubbles stopped completely. I ended up bleeding a bit over 0.5 liter through that brake alone.

Front brakes required a lot less bleeding, there were basically no bubbles at all. I bled a little over 0.2 liter through each.

Last caliper (rear right) was similar to the first, bubbles kept coming for quite some time. Not fully as much as the first caliper though, after just under 0.4 liters I was confident it was enough.

I was going to do clutch last but I ended up skipping it as it turned out I didn't have the correct spanner size with me (9mm)? It was also a bit tricky to get a tool on it without removing the entire airbox, and I determinded that changing the clutch fluid isn't that important anyway.

The reason I would have wanted to change the clutch fluid is simply because the fluid is shared with the brakes which means that absorbed moisture in the fluid in the clutch line can spread to the brake fluid over time, aging it faster.
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Brake bleeding sequence 6R

Post by RUM4MO »

Just in case anyone who still has to change their brake fluid reads this, I have copied the Audi workshop instruction for Audi S4 and RS4 and it gives the same order of wheels as VW do, but it quotes 0.2Litres for front wheels and 0.3Litres for rear wheels and 0.15Litres for clutch, now that is a bigger and longer car than a Polo 6R/6C and has higher capacity master and wheels calliper cylinders.

I'd still think that the first wheel to be to worked on needs a bit more fluid than Audi and probably VW allow for as the initial state or condition is to remove as much fluid from the reservoir as is possible without removing the strainer/mesh basket - but what do DIYers know about anything?
cheba
Silver Member
Posts: 257
Joined: Sun Apr 05, 2015 1:38 pm
Drives: Polo R WRC 2014
Location: Sweden

Re: Brake bleeding sequence 6R

Post by cheba »

This guide is for a mk5 Golf GTI and also states the same order as Haynes to for Polo 6R LHD (FL, FR, RL, RR) (although the Golf in the photos is RHD...): https://www.micksgarage.com/blog/projec ... ur-brakes/

It also states 200ml for front brakes and 300ml for rear brakes. 50ml+50ml for clutch.

They also do the ABS bleeding after the normal bleeding.

It does indeed sound strange that an RS4 with its massive brake calipers wouldn't need to bleed more volume per caliper than a Golf or Polo with single piston calipers.

And yes, the for the first wheel you will definitely have to bleed more unless you have completely emptied the reservoir before filling it up (which is not recommended).
benzinkopf
Gold Member
Posts: 859
Joined: Wed Apr 02, 2014 4:01 pm
Drives: 1.2TSI 105HP DSG7
Location: Malaysia

Re: Brake bleeding sequence 6R

Post by benzinkopf »

cheba wrote:So I'm changing my brake fluid, but I'm a bit confused about the bleeding order. The car is LHD so it has the brake fluid reservoir on the left side and the ABS unit on the right side.

The VW workshop manual states that the correct order is

1. Rear left
2. Front left
3. Front right
4. Rear right

However it doesn't state whether this is for LHD or RHD. Is this correct for my car?

Also I found it strange that the sequence doesn't include bleeding both rear brakes before the front ones (farthest brakes bled first). This is the classic way that I am used to. I tried to google for forum posts discussing brake bleeding on the Polo 6R specifically, and there too it is states that rear brakes should be bled first. So are these people simply doing it wrong?
Mine is RHD. And I think the reservoir(left) n abs unit (right) are the same over here. If you standing in front and facing the engine.


Sent from my iPhone using Tapatalk
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Brake bleeding sequence 6R

Post by RUM4MO »

cheba is meaning Right and Left in the usual and correct way of thinking, ie all references to Right or Left are always "as seen by the driver in the driver's seat looking forward".

Edit:- your car being a RHD has the servo/reservoir on the RHS and the ABS block on the LHS.
benzinkopf
Gold Member
Posts: 859
Joined: Wed Apr 02, 2014 4:01 pm
Drives: 1.2TSI 105HP DSG7
Location: Malaysia

Re: Brake bleeding sequence 6R

Post by benzinkopf »

RUM4MO wrote:cheba is meaning Right and Left in the usual and correct way of thinking, ie all references to Right or Left are always "as seen by the driver in the driver's seat looking forward".

Edit:- your car being a RHD has the servo/reservoir on the RHS and the ABS block on the LHS.
Thanks for your input! I’m expecting that. But it’s funny for me personally to think of engine layout and positioning while we re in drivers seat. But it’s correct. It shud be like that. Hence the right hand headlamp always on the right of the driver.


Sent from my iPhone using Tapatalk
Post Reply