P38A brake system pressure

kermit_rr · Jun 23, 2019

Hi
First off i have no brake problems, the pedal is nice and firm, stops well and the accumulator ok with the pump running only every 4th press of the pedal.
But when the engine is off the system seems to lose pressure fairly quickly, ie. leave the engine off for an hour and the pump needs to run for its full 30 seconds again and the 3 dash lights are on until the pressure builds
Is it normal to lose pressure so quickly?

DanClarke · Jun 23, 2019

Mine has a new accumulator and I often get to the car to find I have a Soft-pedal with a lot of travel.
After the first run of the pump, its all hunky-dory though. I thought this was "normal" behaviour?

domino · Jun 23, 2019

3 amigos should only go when you're moving I believe? At least, the ABS indicator anyway!

kermit_rr · Jun 23, 2019

With pressure in the system, the lights go out after what i assume is a bulb check, is the abs one that goes out when moving

domino · Jun 23, 2019

Ah, fair enough. I hadn't noticed.

Mine is like Dan's, takes a good 10-20 seconds of running after it's been sitting for a while to get up to pressure and then it's fine.

kermit_rr · Jun 23, 2019

Good to know! I'm probably just paranoid searching for problems where there aren't any!
I'll consider that case closed

RangeRoller dt · Jun 23, 2019

ABS goes out as you are going, HB should go off immediately unless it sticks, dunno bout TC I don’t have it.

Mine used to be firm from tickover, now needs few pumps first thing or pressure isn’t quite there. Has only done this since I buggered about with the slave and caused a problem. my Clutch went slack same time, bleed has helped but not same as used to be. I imagine my clutch will burn out shortly

I think it’s possible I got a little air trapped inside the accumulator.

Datatek · Jun 24, 2019

My daily driver has had a full fluid replacement after a failed brake line, the pedal remains firm even after a few days.
The project car on the other hand goes soft overnight but is back to normal by the time I have my seat belt on.
Jumping to conclusions, it may be that the brake fluid is old and/or there is air in the system.

Grrrrrr · Jun 24, 2019

Mine is always hard in the morning ... pedal too.

kermit_rr · Jun 24, 2019

I've got fluid ready to change, so I'll see if that makes any difference

wammers · Jun 24, 2019

System pressure will bleed off and fluid return to the header tank over a period of time with the ignition off. This is quite normal. That is why you do not check and top up fluid level until pump stops. It can take up to 40 seconds for working pressure to be reached with pump running after first start of day..

RangeRoller dt · Jun 24, 2019

Cleaning off my reservoir cap seemed to make a difference to me, but that may just be nonsense in my head.

wammers · Jun 24, 2019

RangeRoller dt said:
Cleaning off my reservoir cap seemed to make a difference to me, but that may just be nonsense in my head.

The reason for your clutch problem was explained at the time.

RangeRoller dt · Jun 24, 2019

Yes sir

wammers said:
The reason for your clutch problem was explained at the time.

I’ve re read Grrr’s thread and think I misunderstood at the time -

I have sucked fluid out of (or created air in) my master cylinder?

Rubberknees · Jun 24, 2019

I mine takes 25 secs for TC light to go out. I take wammers advice not to move car until it goes out so I know pressure is there

P38A brake system pressure

kermit_rr

Very

DanClarke

Well-Known Member

domino

Well-Known Member

kermit_rr

Very

domino

Well-Known Member

kermit_rr

Very

RangeRoller dt

Well-Sprung Member

Datatek

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

kermit_rr

Very

wammers

No longer with us, RIP

RangeRoller dt

Well-Sprung Member

wammers

No longer with us, RIP

RangeRoller dt

Well-Sprung Member

Rubberknees

Well-Known Member

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