Join Date: May 2005
Location: Mayenne France
My Motorhome: Frankia T640 FF2
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!