P38: ABS noisy but now buzzing, accumulator or pump?

[Stufer]

For a long time my abs pump has been quite noisy on initial startup, but by many accounts noise for 15-20 seconds on first start is normal. However yesterday I started up and got quite a loud 'buzzing noise' which cut off after the usual 15-20 seconds. Seems to be coming directly from the pump / accumulator. It also occurs after each brake pedal application. I've done a LRZ search for this increase in noise but not found anything specific. I'm hoping this is just the accumulator and not the pump Any experiences appreciated

 

[wammers]

It should not happen on each application of brake. Noise is your pump trying to fill a knackered accumilator. If motor is noisy may be as well to change the lot.

 

[Stufer]

It should not happen on each application of brake. Noise is your pump trying to fill a knackered accumilator. If motor is noisy may be as well to change the lot.

I'll have to keep an eye on this one for a while, I used it yesterday (to pull a big tree stump out of the garden ) and the buzzing noise had gone, with only occasional pump operation after each pedal press. Can't say I like the look of the 2nd hand units on eBay, but I suppose worth a try against the cost of a new one

 

[Alan C]

I recently fitted a second hand pump sourced from Ebay, I just selected one that looked clean in their photo from as late a car as I could, comparing others against condition, cost etc. Hopefully as most are suppled from breakers yards if they send you a duff one there should be some sort of guarantee. My old pump was leaking brake fluid. I also ordered a new accumulator, no point in using an old one as their life is about 8 to 10 years or so. You could always use your old accumulator, the pump should only run every 2nd or 3rd application of the brake pedal. If it runs on every application then the accumulator is knackered. The accumulator is easily changed with no need to bleed the system. The pump is easy to change too, and I didn't need to bleed the brake system. After swapping the pump I only did the output banjo up finger tight then turned on the ignition, the pump started with gurgles and hissing then a good squirt of brake fluid from the loose union. Turn off, tighten up, top up, clean up, job done.