abs pump running frequently

[Krackatoa]

Hello.

Could someone please give be a bit of advice.

Ive just replaced corroded brake pipes on a friends a 1993 SE. I have bled the system as described in the Haynes manual. The problem i am having is the abs pump will run after pressing the brake pedal as far as it will go 2 or 3 times. My classic dose not have abs so i don't know if this is supposed to happen, is it? My guess is its not. Dose anyone know what might be causing this? My first thought was air but I've bled it 4 times now and I've gone through 4 litres of brake fluid. I have driven it down my track and the brakes work really well and the abs kicks in as well.

Any help would be really appreciated.

Cheers.

[David Sparkes]

Can't account for what work activity might have caused this, but if the complaint of pump running often came in on it's own, the normal suggestion is that the pressure reservoir (bomb) has lost it's pressure and needs changing.

Whatever the cost is, I suggest changing it, as pumps worn out through overuse are a LOT more expensive.

Possibly having all the fluid removed from one side of the diaphragm has allowed the diaphragm to move too far and split. I'm told that normally these pressure reservoirs are changed without needing to bleed the system, but of course you have to clear any residual system pressure before you unscrew the reservoir.

If the diaphragm has split, be prepared for the bomb to be full of fluid instead of Nitrogen, with consequent substantial spillage when removed.

HTH, but these comments are based on reading about the 38A system, rather than the Classic system. You may care to check the components and disassembly comments against a Classic Workshop manual.

[Bowie69]

You'll find with some driving, over the next couple of days say, that it will improve, they tend to self-bleed a bit in my experience.

[SteveRK]

Mine does the same after 2 or 3 full presses. It runs for about 10 seconds i guess. Left for an hour it needs to recharge fully on starting and that runs the pump for about 20-30 seconds.

Does that mean mines knackered also??