Greetings and a Happy Friday from the US...

The ABS booster on my daily driver 2001 P38 has started running almost continuously. For example, at a stoplight with my foot on the brake it won't stop running until I take my foot off the brake. Otherwise I hear it about every 2nd brake push. Looking at the PO's receipt box the accumulator has about 90k (miles) on it so that's likely the cause but it could also be the switch.

I also have a 99 P38 that I need to dispose of finally so I'm thinking I could rebuild that one's ABS booster and swap it in to my 2001. On eBay I see a guy selling 'rebuilt' ABS boosters for $800 USD. https://www.ebay.com/itm/STC2783-RANGE-ROVER-P38-ABS-BOOSTER-PUMP-REBUILT-COMPLETE-UNIT-95-02/
This caught my eye and the reason why I'm asking: "PUMP IS REBUILT WITH NEW SEALS, RACES, PISTONS, SPRINGS ETC." I notice the accumulator he's using has a flat finish so it's definitely aftermarket.

Is that something I can do myself? Replacing with an OEM accumulator, pressure switch and the motor would run me about $400 USD.

To further clarify I'm interested in rebuilding the pump body and replacing with new the accumulator, pressure switch, and motor. What do you guys think?

Sounds like a good idea, this is one of the areas where easy/affordable replacements are not available.
I've seen sometime in the past somewehere some rebuild ideas for the Classic's pump, but never for the P38.
I will follow with interest ...

The two problems I’ve ever found is either the pressure switch, or the sphere , both are readily available, i don’t know anyone whose pulled these apart yet 🤣

I had similar problems on my project and I have today replaced the accumulator and it has stopped running everytime I now press the brake pedal and throwing extra lights at me.

Rebuilding one from the ground up seems new territory apart from the one guy selling them to make some extra dollar

I have never seen a rebuild kit advertised. That link is also dead by the way.
Does anyone know if the wabco pump was used on any other vehicles?

The pressure switch is also used on some Saabs, no idea if the pump is the same though. The one on a Classic is very similar except for the mounting points so probably the same innerds. I pulled mine apart after it burnt out and it doesn't look the sort of thing that can be repaired easily..

Full URL this time

I reached out to the shop owner. He replied that I’d have to talk to his vender about it and to email again on Monday.