P

Petrallis

New Member
P38 1996 4.8 petrol
After replacing the accumulator and bled the brakes(5 times thinking there is air in the system), my brake pedal even with the slightest touch engages the Abs even at standstill, even with ignition off, even with all the relays and fuses out of the abs system but with pressure in the brake system.
If driving and press the pedal the abs locks the wheels and i have a slight pull to the right.
Any help or advise will be appreciated
 
Last edited:
Was it bleed following the correct procedure in Rave the workshop manual as it will mess things up if you get air in the modulator.
 
Petrallis said:
P38 1996 4.8 petrol
After replacing the accumulator and bled the brakes(5 times thinking there is air in the system), my brake pedal even with the slightest touch engages the Abs even at standstill, even with ignition off, even with all the relays and fuses out of the abs system but with pressure in the brake system.
If driving and press the pedal the abs locks the wheels and i have a slight pull to the right.
Any help or advise will be appreciated
Click to expand...

If the accumulator has been dry it can be a total bar-steward getting all the air out. I found on old Ezibleed kit best and just flush the bleed nipple on the accumulator with about 5 litres before doing the rest. Always top up at each step as it gets lower than it looks.
 
Just an update, after bleeding once more. Some air came from the 3rd nipple of the pump and after test driving it i felt the abs for the 1st time so i can definitely say that what i was feeling was the pedal pushing/pulsating back on my foot and not the abs.
That being said, all the calipers and guide pins were checked and they are fine with free movement. No leaks, the pump starts every 4 pedals.
Again the car pulls slightly to the right.
I am thinking maybe a valve inside the booster is stuck? Or the master cylinder is failing? Or maybe i am lucky enough and there is some air trapped inside the booster?
 
Petrallis said:
Just an update, after bleeding once more. Some air came from the 3rd nipple of the pump and after test driving it i felt the abs for the 1st time so i can definitely say that what i was feeling was the pedal pushing/pulsating back on my foot and not the abs.
That being said, all the calipers and guide pins were checked and they are fine with free movement. No leaks, the pump starts every 4 pedals.
Again the car pulls slightly to the right.
I am thinking maybe a valve inside the booster is stuck? Or the master cylinder is failing? Or maybe i am lucky enough and there is some air trapped inside the booster?
Click to expand...
Did you bleed the nipple's in the correct order before going on to the front calipers?
 
Petrallis said:
Yes, every time step by step in the correct order.
I drive the car hoping that if it's air it will move and then after another bleeding, no difference.
Click to expand...
Well I wouldn't be driving the car until you sort it out. I've never had a problem sticking to the bleeding procedure. if you are still getting air out your not bleeding each nipple on the accumulator block enough,and make sure the reservoir is kept topped up at all times,in fact overfill it you can always take some out when the bleedings finished and the system is pressurised.
 
tomcat59alan said:
Well I wouldn't be driving the car until you sort it out. I've never had a problem sticking to the bleeding procedure. if you are still getting air out your not bleeding each nipple on the accumulator block enough,and make sure the reservoir is kept topped up at all times,in fact overfill it you can always take some out when the bleedings finished and the system is pressurised.
Click to expand...

Yeah but this is a modulator that has been completely drained. They can be an utter sod to get all the air out afterwards.

Only other option is if someone has clamped a flexi hose by the caliper and damaged it internally restricting flow.
 
Grrrrrr said:
Yeah but this is a modulator that has been completely drained. They can be an utter sod to get all the air out afterwards.

Only other option is if someone has clamped a flexi hose by the caliper and damaged it internally restricting flow.
Click to expand...

Didn't think of tha flexi hose, maybe thats why it pulls on the right , due to restricted or blocked hose on the other side.
Thanks
 
Grrrrrr said:
Yeah but this is a modulator that has been completely drained. They can be an utter sod to get all the air out afterwards.

Only other option is if someone has clamped a flexi hose by the caliper and damaged it internally restricting flow.
Click to expand...
Right, I've never bled a system that had a drained modulator, I remember you had a right bastard with yours so when I did the brake pipes on both of mine I made sure that.;)
 
Fixed the issue

Just to update the post, after removing the modulator i discovered that one of the servo valves was stuck open letting pressurized fluid pass through and block the front right wheel.
Thats why i felt the pedal pulsating, it had nothing to do with abs.

Many thanks
 
Well thats a new one to add to the list of brake problems, bet that was not easy to find the cause, well done for sorting it:)
 
Petrallis said:
Fixed the issue

Just to update the post, after removing the modulator i discovered that one of the servo valves was stuck open letting pressurized fluid pass through and block the front right wheel.
Thats why i felt the pedal pulsating, it had nothing to do with abs.

Many thanks
Click to expand...
Well done good result:)
 
Petrallis said:
Fixed the issue

Just to update the post, after removing the modulator i discovered that one of the servo valves was stuck open letting pressurized fluid pass through and block the front right wheel.
Thats why i felt the pedal pulsating, it had nothing to do with abs.

Many thanks
Click to expand...

Someone else had jammed valves / corroded springs in the accumulator recently. Seems they're getting to end of life, especially if fluid hasn't been changed at least bi-annually.
 
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