Unsure whether to source another abs pump or modulator block? I'm lost as to what to do next.
1996 RR 4.0 SE hard to stop, pump keeps running
- Thread starter Rover9676
- Start date
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Would those failed plastic pieces cause it to not hold pressure?
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- 19,297
- Location
- Buckinghamshire, UK. ('95 DT)
Don't know. I mentioned it because of the pedal going to the floor and apparently that was what happened. Only read about it though.
If you've tried 2 pumps already a replacement brake modulator seems the next obvious step. Pity you're not closer as I have one in my shed.
Okay. Not sure if I need another abs pump or modulator block? Should I take it somewhere to have the RR Power bled?
Do you think I should have someone Power bleed it? A power bleed should at least remove all air from the system and remove air stuck somewhere in the system from the equation.
Wammers, one more thing tonight. Should I take it and have it Power bled to remove air being stuck in the system somewhere from the equation?
I only purchased 1 pump. I referred to the original abs pump as the second one.
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- 58,170
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- Preston Lancs.
The front brakes are hydrostatic, they do not need pressure in the system to be bled. The rear brakes do not work if there is no pressure in the system and cannot be bled without it. Your problem seems to be that pressure is not being retained in the accumulator. Obviously when the brake is pressed pressure from the accumulator is used. When the brake is released fluid returns to the tank until after several applications, the pump starts again to recharge the accumulator. If the pump never stops the pressure is being lost somewhere. The fault has to be either the pump NRV or a valve in the ABS unit stuck open allowing fluid to return to the tank. You can bleed the system to your hearts content but it will not cure the pressure loss. Does your car have rear wheel traction control with a TC lamp that comes on with ignition? If so this lamp should go out when minimum working pressure is achieved but the pump should still run for a while after this lamp goes out before full pressure is gained and it stops. You could try fitting a blanking plug in the high pressure feed from pump to ABS unit. If with this plug fitted the pump stops the problem is with the ABS unit. If it does not stop the problem will be with the pump NRV.
Wow I understand. What's a blank plug and where can I get one or do I make one? Is the high pressure feed the black hose connecting the pump and reservoir? Would cut that hose to insert the plug or are you saying I would disconnect the hose from the pump and place the plug there? Oh, I do have TC light that would come on and go off.
Thankkkkk Youuuu!
To source an abs unit I have to the same part number (ANR2239) to ensure a proper-match, correct?
RangeRoller dt
Well-Sprung Member
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Same type as original yes (not sure what one - we can’t see it)
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- 58,170
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- Preston Lancs.
No the pipe from the tank is the low pressure feed to the pump you need to blank the high pressure feed from the pump to the ABS modulator. The pressure pump is a self contained autonomous unit, all it does is supply pressure to the system. None of the other parts of the braking/ABS system control it. It runs when pressure in the accumulator is low and switches itself off when full pressure is obtained. If you blank off it's outlet it should stop when full pressure is obtained. Switch ignition on and wait for TC to go off (minimum working pressure). Then switch off and back on. If TC lamp has come back on you have a bad pressure leak.
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Haven't read all 6 pages, but the pump relay is known to stick on....just incase it hasn't been mentioned - if it has, ignore me - most do!!
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- 58,170
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- Preston Lancs.
That has already been pointed out and the OP says a new relay fitted. I/we can only go on info received.
PS. I hope he realises that the ABS power relay has nothing to do with the pump. And it is the Black relay #17 that powers the pump. But he has a far more serious fault than a stuck relay.
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- Posts
- 19,297
- Location
- Buckinghamshire, UK. ('95 DT)
Worth mentioning, certainly. A relay has to be the cheapest option!
- Posts
- 58,170
- Location
- Preston Lancs.
I rather think that the OPs answer when i asked how quickly the fluid returns from the accumulator to the tank after the pump stops sort of is the main concern. The pressure should be retained within the accumulator. It is normal for it to bleed off slowly over time. But it should not run straight back into the tank when the pump stops.
At work now, just read the posts. Is there any way to check the accumulator? It has also been replaced but, it is used.
- Posts
- 58,170
- Location
- Preston Lancs.
You have fluid leaking back from storage into the header tank. The accumulator at this time an irrelevance.
Wammers, Thanks for clarifying!
If you weren't comfortable with the Blanking Plug procedure, which part would you source first, The Modulator/Block (ABS Unit under the reservoir) or the Pump (The unit with Accumulator sitting on top)?
Still don't know what's a Blanking Plug?
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brianp38dse
Well-Known Member
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- heathrow
Blanking plug = stop end on pipe or hose that comes out of the pump to the modulator.
