Excessive brake pedal creep

[james robert]

Hello, i'm sure this may have been asked before but i'm after a bit of help.
My brake pedal on my 2005 ducato based motorhome (no abs) is firm when the engine is turned off, but when you start the engine it sinks to the floor when pressed wothin about 10 seconds. All the internet says is it is a thing called deisel creep but it seems excessive compared to other diesels i have owned. I have replace the master cylinder in case the seals where going but no change. Thanks for any help

James

 

[EuroTrotters]

Very often a problem with the brake fluid.

How old is the fluid ?
Have you bled the system ?

It could be contaminated with moisture or have air in it.

 

[Barchetta47]

I have a 2004 Ducato which we have owned for 7+ years. The brake pedal has always behaved as you have described on start up but a quick push of the pedal returns it to ‘normal’. Until now I’ve never considered it an issue

PS: Brake fluid changed at last service and still the same.

 

[james robert]

Brake fluid change last year when replacing master cylinder and again yesterday this time with 5.1 dot and just replaced all the rubber hoses in case one was ballooning. I have bleed a good 2 to 3 litres through the system, from my haynes manual it holds about 1 litre in total and no bubble coming through when bled. The mot tester on its last test commented how the peddle didnt feel right and the rear brakes just scraped through on efficency, but that could of been because i didnt empty it and it was fully loaded.

 

[Bill-H]

Mine has always gone about 1/2 way down in the situation you describe, I always assumed to was something to do with the servo assistance, and the brakes work perfectly after taking your foot off that first time when starting.

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[Steve N Tracy]

Because there is minimal vacuum in a diesel inlet manifold unlike a petrol they have a vacuum pump powered by the engine, these can create a much higher vacuum then what you get in a inlet manifold so if you keep your foot on the pedal you will get what is sometimes known as "diesel creep" it's normally nothing to worry about.

 

[Oldrat]

With the engine off the pedal should press down a little way and then be firm, no further movement down. Keep the pressure on and start the engine, the pedal should drop a little as the servo comes on.
That is normal, if it’s anything else, it needs checking out.

 

[Just smiffy]

Wheels off and clean up all the brake parts make sure none are binding, I had a little of this and I changed the discs and pads and it was much better…

 

[oldiesontour]

My last van 2011 iveco was as you describe would slowly(very) creep to the floor with the engine running...but drove perfectly normally,passed several MOT s I t worried me for a while but on asking around and after routine new discs,pads,rear calipers and then master cylinder,I accepted what others said they are all like that.

 

[james robert]

Wheels off and clean up all the brake parts make sure none are binding, I had a little of this and I changed the discs and pads and it was much better…

Had new front discs last year and just done rears, just fitted brembo brake pads front and rear. All new spring clips and slider pins lubed with silicone grease and still the same. Its got me running out of ideas lol thanks