Technical More bleeding brake woes

[toyogran]

Hello again
I thought I had solved my 'low brake pedal' problems last year but still have to dab the brake pedal occasionally to bring it up to what I consider to be the proper pedal height and firmness on our 2005 2.8jtd maxi motorhome.
I have replaced last year the discs and shoes, had the slave cylinders off and bled the system several times (using a variety of methods, gravity, conventional her indoors pedal actuation operation, vacuum at the brake nipple etc) and don't seem to see any signs of air. Despite this I still have a very firm pedal with engine off, very firm after a couple of dabs with engine running but after driving for a while and coming to use the foot brake there are a couple of inches or so of pedal travel before the brakes 'bite'.
My question is could it be ageing master cylinder seals or air in the ABS pump circuit not enabling me to get a really firm, high pedal?
I have always been very careful not to let the MC get low when bleeding and done all the things I can think of to resolve the problem.
It passed it's mot fine in the braking dept in terms of efficiency but bugs me that you always have to keep dabbing the pedal to keep it high where it should be!
Has anybody any experience of using multieuscan to cycle the abs pump when bleeding or should I leave well alone!
Any comments or advice really appreciated.

 

[shotgun]

if the pedal is creeping down yes I would say its the master

 

[Deefordog]

+1 for master cylinder.

 

[errolmorris]

Sounds like a by-pass issue with the master cylinder.
A lot of gunk accumulates in the bottom of the master over time and when it comes time to bleed the system, the seals are pushed beyond their usual path and the gunk will bugger the seals as they move back and forth.
It is a very common problem and easily remedied with a new kit and light honing of the master cylinder or total replacement, especially if moisture has caused pitting of the cylinder. As you know, brake fluid attracts water and of course some dust will be collected over a period.
Some service/repair kits come with a sleeve for the master.

 

[toyogran]

Thanks everybody for your diagnoses.
If I take the master cylinder out (to replace or repair) will I run into any problems with getting air into the ABS pump and need to cycle the abs pump to shift any trapped air?
What about the clutch as I think they share a common reservoir?
I will get the bits for the master cylinder and have a go when we get from our current winter trip and hopefully get it sorted properly once and for all.
Will let you know when I put it all back together.
Thanks again, any pointers about changing the MC welcome

 

[errolmorris]

Thanks everybody for your diagnoses.
If I take the master cylinder out (to replace or repair) will I run into any problems with getting air into the ABS pump and need to cycle the abs pump to shift any trapped air?
What about the clutch as I think they share a common reservoir?
I will get the bits for the master cylinder and have a go when we get from our current winter trip and hopefully get it sorted properly once and for all.
Will let you know when I put it all back together.
Thanks again, any pointers about changing the MC welcome

Have you sat with your foot lightly on the brake pedal with the engine running? If you press hard on the pedal it shouldn't move once the pressure is applied, so a gentle pressure is what is needed.
You will feel the pedal slowly sink towards the floor and if so, this will indicate either air in the system or fluid leaking past the rubber valve in the master.
Check up under your dashboard to see if you can see if any oil has seeped through. If you have oil inside the cabin where the master cylinder shaft connects the brake pedal to the cylinder, you will know the master cylinder is the culprit. No oil does not mean it is okay, just that it is not leaking.

It's unlikely that removing the master cylinder will cause air to enter the lines, but remember to bleed the master cylinder before you fit it back into position.
You may still have to bleed the system anyway and remember start bleeding from the farthest brake cylinder if you are unsure and it wouldn't hurt to bleed the slave cylinder as well...just to be sure.

 

[varesecrazy]

The foot on pedal test should be a good indicator..
if its rear shoes..are they properly adjusted/ ing.as that will make for LONG pedal travel too.
Charlie

 

[merovingian]

I have the same problem on the same vehicle, had the fluid changed last year by a garage and sponginess has got worse slowly since. I have checked for leaks found all is dry and ordered a eezibleed to do the job.
The fluid was 10 years in the lines before i had it changed and i reckon this has ruined the Master Cylinder seals but I see no fluid leaks inside the cab or around the MC. I don't know if changing the MC fixed the problem for Toyogram or not

 

[errolmorris]

I have been wondering how it all went as well.
If all the other work has been done then a new master cylinder sounds like the way to go especially since you say the fluid is around 10 years old.
As for the hard pedal with the engine off, that is perfectly normal even if the master is buggered. With the 'vacuum assist' operating, the problems become obvious.
Just because there is no obvious fluid leak doesn't mean that it is not bypassing. Remember there are two brake systems working off the master cylinder. One for the front and one for the rear brakes.
For my money, I'd replace the master without a second thought.

 

[corcai]

I have the same problem on the same vehicle, had the fluid changed last year by a garage and sponginess has got worse slowly since. I have checked for leaks found all is dry and ordered a eezibleed to do the job.
The fluid was 10 years in the lines before i had it changed and i reckon this has ruined the Master Cylinder seals but I see no fluid leaks inside the cab or around the MC. I don't know if changing the MC fixed the problem for Toyogram or not

Have you checked pads / calipers, seized calipers and resulting wedge shaped pads, can give a springy feeling that can be mistaken for spongy.

Empty the servo by pressing the brakes few times with the engine off until assistance is gone. Allow it to rest for a few minutes.

Press the brake, if the pedal feels spongy pump it several times does it feel less spongy with each stroke? Yes - Air, No - Seized caliper, pad issues.

Press the brake pedal hard and keep applying pressure,does it gradully sink - Master Cylinder.

 

[merovingian]

Have you checked pads / calipers, seized calipers and resulting wedge shaped pads, can give a springy feeling that can be mistaken for spongy.

Empty the servo by pressing the brakes few times with the engine off until assistance is gone. Allow it to rest for a few minutes.

Press the brake, if the pedal feels spongy pump it several times does it feel less spongy with each stroke? Yes - Air, No - Seized caliper, pad issues.

Press the brake pedal hard and keep applying pressure,does it gradully sink - Master Cylinder.

Well, I see no evidence of pad or caliper issues all looks normal, I have ordered new parts including a MC and a Gunsons eezibleed kit which I will attach to my compressor, I will have another go at the weekend when I have time, the pedal symptoms: The servo is functioning fine, the sponginess goes when the brakes are pumped, but hard constant pressure and the pedal sinks slowly down; so, maybe it's a bit of both?

 

[toyogran]

Just to keep you up to date.
Have had another go at bleeding and changing the brake fluid before I change the MC over as I had major problems on a VW Golf after replacing a MC and shifting the air in the MC itself even though it has its own bleed nipples.
Short term the pedal feels better but reverts to "vague" after a longish run so I think it's a matter of biting the bullet and getting it done.
As a matter of interest a friend has a 244 Maxi and the brake pedal on his doesn't feel much better! He reckons it's a Ducato thing!
In the process of doing the cam belt at present as urgently needs a change on age grounds and don't want a disaster whilst on an extended trip.
Who designed the access to the alternator adjustment? Have ordered a universal jointed spare arm with built in eyeballs to see what's going on while trying to get at the adjuster over the back of the drive shaft!
Keep taking the tablets.

 

[corcai]

Who designed the access to the alternator adjustment? Have ordered a universal jointed spare arm with built in eyeballs to see what's going on while trying to get at the adjuster over the back of the drive shaft!
Keep taking the tablets.

Probably a direct transplant from iveco where the engine is longitudinal.

A ratchet ring spanner makes it a bit easier.

 

[merovingian]

You can hardly get your arm through the gap it's a bloody nightmare

 

[rolandbrindley]

My 1992 LHD Ducato 10 TD has always had a long brake pedal travel when driving, compared to a short travel when standing. I have been through the entire brake system and front axle assembly and put it down to excessive runout of the front disks which causes the pads to retract more than is necessary as you drive along, meaning more brake fluid needed when you brake. Worn front wheel bearings could aggravate this condition.

But mine doesn't have ABS which for you complicates matters further. I think bleeding an ABS system never gets the fluid inside the ABS pressure reservoirs and pump changed, unless you can motor the ABS pump while bleeding. I have a headache with the ABS on our 2009 Jeep Compass CRD for just this reason, how to motor the pump while bleeding the brakes?

The application of ABS for private vehicles was one of the worst steps taken by the motor industry and is now being questioned for it's effectiveness.

 

[corcai]

Loads of tools readily available that will bleed abs, Multiecuscan, alfaobd, lexia, pp2000, multidiag, wurth/delphi/autocom, launch, snapon etc. etc.

Who exactly is questioning the effectiveness of abs? I lived in a rural area for 12 years roads would often be covered in chippings, slurry, clay from tractor tyres, grass growing in the middle of the road and you often drove with two wheels in the ditch when passing another car. Several times a day you'd have 2 wheels on asphalt, 2 on grass/gravel/cow****/earth. You very quickly learn to appreciate abs in those kind of conditions.

 

[digger58]

I have just done the brakes on my 02 2.8, new front caliper seals and pads, new wheel cylinders and shoes, the wheel cylinders were in a very poor state and weeping, very rusted inside, changed fluid and then found it hard to get a pedal, eventually changed MC as well, old one was a bit nasty looking inside. Still found it hard to get a decent pedal. eventually called a friend who does commercials every day and he he said he has come across at least 3 duff new MCs for Ducatos recently! He said pressure up to 25psi and also pump pedal at the same time, eventually got it done. The brakes have never been so good since I've owned it and also a decent handbrake now. Still never failed a test with the old ones!

 

[merovingian]

My 1992 LHD Ducato 10 TD has always had a long brake pedal travel when driving, compared to a short travel when standing. I have been through the entire brake system and front axle assembly and put it down to excessive runout of the front disks which causes the pads to retract more than is necessary as you drive along, meaning more brake fluid needed when you brake. Worn front wheel bearings could aggravate this condition.

But mine doesn't have ABS which for you complicates matters further. I think bleeding an ABS system never gets the fluid inside the ABS pressure reservoirs and pump changed, unless you can motor the ABS pump while bleeding. I have a headache with the ABS on our 2009 Jeep Compass CRD for just this reason, how to motor the pump while bleeding the brakes?

The application of ABS for private vehicles was one of the worst steps taken by the motor industry and is now being questioned for it's effectiveness.

Having read a bit on the subject it has to be done with special equipment which I suppose only the main stealer will have, ha now I have seen Corcai's post! Well, If i get no improvement they have announced a bit of Sun tomorrow, I have no garage yet but am waiting for planning permission to build a big one to take the Hymer and car and I will remove the rear disks and drum for the handbreak. All is dry externally but we will see

 

[rolandbrindley]

I have also experienced trouble with water accumulating in the rear brake cylinders on my 1993 Ducato 10 motor-home. This rusts the cylinder bores and blocks the pistons when you brake, resulting in poor or no rear axle braking. The handbrake will be unaffected as the linkage is all mechanical.

When the rear wheel cylinders get like this there is no easy solution, replace them as they will be pitted, and change the fluid in the entire system as it now contains water.

Incidentally I have read in Jeep documentation somewhere that ABS is indeed of limited value and can cause more trouble than it avoids. It was developed for a quite different application, heavily loaded commercial aircraft, and for private car use a bit of careful driving and experience works wonders.

Some much-praised braking aids can indeed get you into big trouble, the Telma for example. Switch this onto position 4 in the wet with an unloaded truck and you will find the back end overtaking you in a hurry!

 

[toyogran]

Update two.
Just fitted a new master cylinder.
Bleed it with a combination of gravity and using an Easybleed at 25psi.
Brakes brilliant, braking starts just touching the pedal and very firm.
Just got to sort the water pump now!
Thanks for the input and advice.