ducato brake problem - Motorhome Forums, Motorhome Discussion, Motorhome Chat

User Tag List

 3Likes
  • 1 Post By Captdave
  • 2 Post By eurajohn
 
LinkBack Thread Tools
post #1 of 10 (permalink) Old 19-05-2017, 15:38 Thread Starter
Junior Member
 
Join Date: May 2017
My Motorhome: I drive...
Posts: 2
Thanks: 0
Thanked 1 Time in 1 Post
ducato brake problem

Hi there
im a newbie and looked through alot of problems you guys are having but none seem to match my problem which is
i have a ducato motorhome tag axle with a lot of travel on my footbrake, when i put my foot on the brake with engine off i have a good solid brake but when i start the engine and the servo kicks in the brake pedal travels a long way down and the brake feels spongey any idea why it is like this or is this normal
thanks for any replies
Pete
tower-block is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old 19-05-2017, 16:04
Senior Member
 
raynipper's Avatar
 
Join Date: Aug 2008
Location: Normandy. Just up the D903 from the roundabout with the D15
My Motorhome: Hobby 750 now sold.
Posts: 24,101
Thanks: 1,234
Thanked 474 Times in 446 Posts
Send a message via Skype™ to raynipper
Hello Pete.
My Hobby Tag was the same and never gave me confidence when braking. Eventually I put it into a local Peugeot agent and they said it needed pads and discs.
So told em to get on with it as they had everything in stock and next day new discs, pads, fluid and stops like a car now. But it did cost about €700.

Ray.

The FSA licensed a twice convicted fraudster to handle our life´s savings. Guess what? He robbed us of £750,000. http://raynipper.com
Brexit is madness orchestrated by the insane.
raynipper is offline  
post #3 of 10 (permalink) Old 19-05-2017, 16:58
Senior Member
 
fdhadi's Avatar
 
Join Date: May 2005
Location: Wigan, Lancs
My Motorhome: Burstner A747
Posts: 1,447
Thanks: 75
Thanked 14 Times in 13 Posts
Hi Pete.

How old is your M/H and what mileage?
I think I would start by bleeding the brakes, I did this on our 04 plate tag last year and found a difference.

Frank
fdhadi is online now  
 
post #4 of 10 (permalink) Old 19-05-2017, 17:52 Thread Starter
Junior Member
 
Join Date: May 2017
My Motorhome: I drive...
Posts: 2
Thanks: 0
Thanked 1 Time in 1 Post
hi
it is 6 years old and 17000 miles the disc and pads look good i would not expect it to want new disc yet but maybe it does, ima bit like you
raynipper no confidence when braking.
pete
tower-block is offline  
The Following User Says Thank You to tower-block For This Useful Post:
raynipper (19-05-2017)
post #5 of 10 (permalink) Old 19-05-2017, 18:42
Senior Member
 
Pudsey_Bear's Avatar
 
Join Date: Sep 2008
Location: Keighley, Still in Gods County.
My Motorhome: 2002 Bessacarr E745.
Posts: 38,256
Thanks: 1,554
Thanked 989 Times in 929 Posts
Send a message via AIM to Pudsey_Bear Send a message via Yahoo to Pudsey_Bear
Hi Pete, welcome to MHF.

I'd deffo get it into a decent garage who know what they're doing, it could be many things, but it needs sorting.
Pudsey_Bear is offline  
post #6 of 10 (permalink) Old 19-05-2017, 19:57
Junior Member
 
Join Date: May 2017
My Motorhome: I drive...
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
Changing the brake fluid after 6 year is the start of diagnostics.. Brake fluid has the tendency to collect water during these years and the effect on braking is massive.
seth_space is offline  
post #7 of 10 (permalink) Old 07-01-2021, 14:33
Junior Member
 
Join Date: Dec 2020
Location: Mallorca
My Motorhome: Hobby 750fml
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by tower-block View Post
Hi there
im a newbie and looked through alot of problems you guys are having but none seem to match my problem which is
i have a ducato motorhome tag axle with a lot of travel on my footbrake, when i put my foot on the brake with engine off i have a good solid brake but when i start the engine and the servo kicks in the brake pedal travels a long way down and the brake feels spongey any idea why it is like this or is this normal
thanks for any replies
Pete
Hi,

I have exactly the same problem even failed its ITV (Spanish MOT) for brakes being inefficient but as a retired mechanic I saw this as something of a challenge so set about fixing it. I first checked the master cylinder by disconnecting the brake pipes and fitting two bleed screws in their place and the pedal was rock hard as it should be. Next tried the same system by using the bleed screws on the ABS module in place of the rear brake lines again a very positive hard pedal just a very small amount of travel as I was now operating the front brakes only. So this is quite positive it means the fault is to the rear and with 4 x 15 year old brake hoses I think that is the place to start.
The pedal would slowly sink right to the floor with the engine running but was quite hard without the engine so I am thinking the extra force of the servo was enough to expand the brake hoses to give a sinking pedal. I have ordered some top quality brake hoses so hopefully this will fix it as all the discs and pads seem to be in excellent order almost new in fact. I am guessing that the last owner had problems too and had them all renewed and just scraped through the ITV. I will keep you informed if this cures the fault once the hoses arrive as I know there is a bit of a problem with Tag axle brakes.
raynipper likes this.

Last edited by Captdave; 07-01-2021 at 14:37.
Captdave is offline  
post #8 of 10 (permalink) Old 08-01-2021, 15:26
Senior Member
 
Join Date: Jun 2007
Location: Belfast
My Motorhome: Hymer Exsis-i 504
Posts: 9,724
Thanks: 193
Thanked 522 Times in 495 Posts
That's good information Pete. I doubt the OP will be back to say thanks as his only 2 posts were on this thread back in 2017!

Jean
jiwawa is online now  
post #9 of 10 (permalink) Old 08-01-2021, 15:50
Senior Member
 
Pat-H's Avatar
 
Join Date: Oct 2009
Location: Hertfordshire
My Motorhome: Swift Lifestyle 590RS
Posts: 7,316
Thanks: 4
Thanked 184 Times in 179 Posts
Send a message via MSN to Pat-H
Don't some trucks (and therefore MHs) have a rear lift detector in the brake feed to the rear axle? If the rear lifts up it reduces the braking force to the rear wheels to stop them skidding and sliding sideways.

Another simple part of expanding that testing is to use a pair of mole grips to clamp the start of the rubber brake pipe. Then clamp the end of the rubber brake pipe and see if its any different.
The long metal brake pipe run could also be expanding and contracting slightly (but less likely) other than that it could be the rear brake seals expanding under the pressure.
Or the caliper for the brakes is stiff and as the piston comes out the caliper gets forces along. But normally a few peddle pumps brings a very hard peddle that only gets softer again as you roll along were the deliberate brake disc run out forces the caliper away again.
So plenty of potential issues to explore.

Pat

Now just waiting until we decide to rejoin.
Happy to actively support Black Lives Matter because all lives do matter even black ones.
Pat-H is offline  
post #10 of 10 (permalink) Old 09-01-2021, 06:59
Senior Member
 
eurajohn's Avatar
 
Join Date: May 2005
Location: Mayenne France
My Motorhome: Frankia T640 FF2
Posts: 3,309
Thanks: 52
Thanked 228 Times in 205 Posts
This problem is well known and much has been written about it, a Google search for diesel vehicle brake servo creep or pedal creep will provide many suggestions.

Diesel engine vehicles use a pump to generate the vacuum for servo assistance.
Unlike the inlet manifold of a petrol engine, there is no vacuum relief with a pump. If excessive pedal pressure is applied when the vehicle is stationary with the engine running the hydraulic pressures required to stop the vehicle will be grossly exceeded.
Larger vehicles such as vans and 4x4s are more prone to this problem as they use servos with a higher boost ratio.
The problem is often incorrectly diagnosed in a variety of ways.
So long as the braking performance is within standards and no leaks or failed parts are on the system, the solution is to stop applying the excessive pressure.

However If you can get the brake pedal to creep with the engine switched off and servo exhausted, there is a serious problem that requires urgent attention!

.
raynipper and dghr272 like this.

John
eurajohn is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Motorhome Forums, Motorhome Discussion, Motorhome Chat forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome