S40d 06 strange noise

toppin39 · Post by **toppin39** » 01 Feb 2011, 07:15

On my s40 diesel i have a strange noise,the noise only comes on after you drive the car round about 10mph
it sounds like a crunch.thinking 1st gear was going, i then pulled away in 2nd 3rd the same noise appeared
again at hte same speed but this will only happen the once and as long as the engine is not stopped,you can go up
and down gears as normal with no more noise but like i say soon as you stop the car and start again then at the same speed no
matter what gear the noise appears only the once until ,everytime the car is started and driven.

Post by **jimmy57** » 01 Feb 2011, 11:04

The ABS system running its self test will cause the pump motor and the hydraulic circuit valves to be operated one pulse.
It does it with every key on cycle once when you first move and there can be a less involved test when you stop and take off again with no ignition switch on or off.
Is the car new to you or did the noise just now begin?
If you have owned the car nad the noise just started were there any repairs made in engine compartment just before it began the noise?