RBT252

I have a whining noise that gets louder when revving the engine.
My mechanic said it was the ABC Pump, so I purchased a reconditioned unit.

I booked to get it installed this morning and asked him to check the AC pump and the Accumulator/Pulsation Damper as these have been known to fail.
He put the car on a ramp and placed a long screwdriver on the ABC pump and the other end to his ear, there was a loud grinding noise, although not as loud as the whining noise.
We did the same with the AC pump/compressor and there was a slight noise coming from it too, this noise was quieter and we were both unsure if it was just the sound of the AC pump, or if there was a problem, I have opted to replace this too as it's only £165

When he placed the screwdriver on the Accumulator/Pulsation Damper, he said it was silent.
The car has done 72K miles and I think it would be worthwhile replacing the damper at the same time as fitting both pumps.

I do not know what the part number is for the pulsation damper which is next to the ABC pump, can anyone help?

I know there are small ones and larger ones, but I don't want to order the wrong part.

If anyone has any other thoughts on what the whining noise may be, please share your thoughts.
I will record a video of the noise later this afternoon and post it.

geepower

I have the same noise in my 2013 CL550. It is an intermittent noise like in this video. I ordered the pulsation damper of the tandem ABC pump. Hopefully, it will resolve the issue. It might be the pressure reservoir of the suspension as well (I am not sure if mine has a pressure reservoir at all yet).

There is the Xentry topic regarding this issue: topic # LI32.50-P-048280 - Humming/howling noise from ABC suspension up to approx. 2000rpm.