Brake bleeding not working - Page 2

3disco · 22nd October 2016, 11:37

Possibly air trapped in the abs unit which would need t4 to open all valves/ports.

T-Cut · 22nd October 2016, 11:40

It's said that purging a replacement ABS module (indeed normal brake bleeding) requires a T4 or similar to control the internal valves. The MGR manual however dosn't mention T4 in the section covering ABS replacement. It simply refers to standard brake bleeding methods.

TC

SNAP!

SD1too · 22nd October 2016, 16:08

Quote:

Originally Posted by T-Cut

It's said that purging a replacement ABS module (indeed normal brake bleeding) requires a T4 or similar ...

I don't know about a replacement ABS module but normal brake bleeding does not require a T4 or similar. I have done mine conventionally and successfully. Also remember that the ABS system must be fail safe, so in the event of a fault, fluid has to be able to travel unhindered between reservoir and brake pads.

Simon

T-Cut · 22nd October 2016, 19:39

I've also bled car brakes the 'normal' way since I was a teenager and my 75's in exactly the same way. However, a few years ago the T4 blokes introduced us all to the 'proper' way to do it - but MGR don't mention anything that I don't do myself. Certainly T4 has an ABS valve opening routine, but whether it's essential to good brake bleeding is clearly debatable. Whether it's essential to filling/purging a new ABS module is equally debatable since the workshop manual simple refers you to the conventional bleeding method after fitting a new dry module. However, a 2011 post from a brake bleeding specialist suggested that brakes should be bled with the ignition 'on' to open the ABS valves. The use of a 20psi pressure kit was also recommended. These observations were made in the context of the Sinking Pedal Phenomenon, which happens in all 75/ZTs, yet was said to disappear after a T4 bleeding session. In a subsequent test, SPP wasn't was not affected by the ignition-on method, so it all remains debatable.

TC

klarzy · 22nd October 2016, 19:49

I con only suppose that it assists with the removal of trapped small air bubbles and or old and possibly hydroscopicaly contaminated fluid in the ABS module itself

SD1too · 22nd October 2016, 20:07

Quote:

Originally Posted by T-Cut

... a 2011 post from a brake bleeding specialist suggested that brakes should be bled with the ignition 'on' to open the ABS valves.

Oh no, not another "specialist".

Last week I retracted my caliper piston to fit new brake pads. The ignition was NOT switched on. Brake fluid passed unhindered from caliper to master cylinder, where I extracted it with a syringe. The ABS valves must therefore have been open and so it follows that the "specialist" to which you refer is talking a load of tosh (as James May would say).

Simon

T-Cut · 22nd October 2016, 20:20

Quote:

Originally Posted by SD1too

- - - it follows that the "specialist" to which you refer is talking a load of tosh.

Dunno. It was Derek Frost (derek999), maybe you should tell him.

TC

Chuckles · 23rd October 2016, 16:38

Well everyone; I have tried all that has been recommended, thank you one and all. It would appear that the first thoughts of a failed Master Cylinder valve is still top of the list. The problem now is can it be repaired?
I have two manuals and one does mention they are a sealed unit; how stupid is that?
So the hunt is on for a replacement now. What a quandary ... will a second hand unit be dried out? enough to give the same result and if so that wouldn't prove the original problem.
I have not been able to trace a new/remanufactured unit so ... mmmmm. Who knows!

eric27 · 24th October 2016, 10:32

I have a question.
I have been thinking when you disconnect the battery before you start bleeding the brake systeem the internal valves are then open and there is no power to the abs module to close the valves.
So you can bleed the brake system.
Am I wright?

Eric.

3disco · 24th October 2016, 10:47

If only it was that easy it would make the t4 redundant for this operation,I tried everything to get a decent pedal but the only way in the end was the t4 session,(central motors in chard said it was the first time that they had to use the t4 to bleed the brakes).

22nd October 2016, 19:49	#15
klarzy This is my second home none but not gone Join Date: Mar 2013 Location: March, Cambs Posts: 16,437 Thanks: 894 Thanked 4,247 Times in 3,025 Posts	I con only suppose that it assists with the removal of trapped small air bubbles and or old and possibly hydroscopicaly contaminated fluid in the ABS module itself __________________ [SIGPIC][/SIGPIC]….All praise Bananaswan….

23rd October 2016, 16:38	#18
Chuckles Gets stuck in NOW a Club Tourer was 1999 - 75 2.0Ltr Connoisseur SE petrol Saloon Join Date: Jan 2012 Location: Iwerne Minster, Dorset Posts: 552 Thanks: 63 Thanked 54 Times in 47 Posts	Well everyone; I have tried all that has been recommended, thank you one and all. It would appear that the first thoughts of a failed Master Cylinder valve is still top of the list. The problem now is can it be repaired? I have two manuals and one does mention they are a sealed unit; how stupid is that? So the hunt is on for a replacement now. What a quandary ... will a second hand unit be dried out? enough to give the same result and if so that wouldn't prove the original problem. I have not been able to trace a new/remanufactured unit so ... mmmmm. Who knows! __________________ Chuck Nth. Dorset. UK Membership #1896 Don't take life so seriously.... it is not permanent!

22nd October 2016, 11:37	#11
3disco 3disco ROVER 75 CONN TOURER CDTI and ZTT V8 SE LPG Join Date: Sep 2008 Location: chardstock.axminster,devon Posts: 1,493 Thanks: 361 Thanked 94 Times in 85 Posts	Possibly air trapped in the abs unit which would need t4 to open all valves/ports.

22nd October 2016, 11:40	#12
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,752 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	It's said that purging a replacement ABS module (indeed normal brake bleeding) requires a T4 or similar to control the internal valves. The MGR manual however dosn't mention T4 in the section covering ABS replacement. It simply refers to standard brake bleeding methods. TC SNAP!

22nd October 2016, 19:39	#14
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,752 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	I've also bled car brakes the 'normal' way since I was a teenager and my 75's in exactly the same way. However, a few years ago the T4 blokes introduced us all to the 'proper' way to do it - but MGR don't mention anything that I don't do myself. Certainly T4 has an ABS valve opening routine, but whether it's essential to good brake bleeding is clearly debatable. Whether it's essential to filling/purging a new ABS module is equally debatable since the workshop manual simple refers you to the conventional bleeding method after fitting a new dry module. However, a 2011 post from a brake bleeding specialist suggested that brakes should be bled with the ignition 'on' to open the ABS valves. The use of a 20psi pressure kit was also recommended. These observations were made in the context of the Sinking Pedal Phenomenon, which happens in all 75/ZTs, yet was said to disappear after a T4 bleeding session. In a subsequent test, SPP wasn't was not affected by the ignition-on method, so it all remains debatable. TC

24th October 2016, 10:32	#19
eric27 Regular poster Rover 75 saloon Join Date: Feb 2011 Location: Dedemsvaart, Netherlands Posts: 70 Thanks: 1 Thanked 7 Times in 6 Posts	I have a question. I have been thinking when you disconnect the battery before you start bleeding the brake systeem the internal valves are then open and there is no power to the abs module to close the valves. So you can bleed the brake system. Am I wright? Eric.

24th October 2016, 10:47	#20
3disco 3disco ROVER 75 CONN TOURER CDTI and ZTT V8 SE LPG Join Date: Sep 2008 Location: chardstock.axminster,devon Posts: 1,493 Thanks: 361 Thanked 94 Times in 85 Posts	If only it was that easy it would make the t4 redundant for this operation,I tried everything to get a decent pedal but the only way in the end was the t4 session,(central motors in chard said it was the first time that they had to use the t4 to bleed the brakes).