Hello fellow T4 owners,
We have 1998 T4 2.5TDi ACV panel on 223,000miles, partly converted.
There’s no difference in the brake performance when driving. But when I get to a destination and turn off the engine, I can hear a subtle whining/buzzing noise coming from around the coolant reservoir (the black N75? boost control valve solenoid??). I then pump the brake pedal a couple of times, the whining pitch goes higher and then stops.
For couple of occasions I sat in the van after turning off the engine and the noise eventually goes off, perhaps after a couple of minutes. I also tried to turn on the engine and off again, and the whining noise sometimes stays on after the engine is off.
It’s not impacting on the braking performance but I don’t think it ever did this so I’m’ wondering what is causing this whining noise post-engine off and whether I need to repair something.
What do you think? Many thanks for any suggestions or advice.