No Brake Pressure

[Graaf]

Well, I locked the car away at the end of last year and all was working well.

Nice day today so I thought that I'd take it out for some fresh air.

No pressure at the brake pedal, pedal goes straight to the floor. I'm really glad I tried it before I took the car out.

The fluid reservoir is full and there are no signs of any leaks.

What could it be???? Hopefully easy fix????

Thanks

[Tuga2112]

pump that brake pedal a bit and confirm if the reservoir is losing fluid.

if its level is going down
most likely a small leak in one of the calipers => look around the car for any signs of fluid on the floor near any of the wheels.
when you find it. get a replacement nipple and bleed that corner

obviously. you may have a leak in the piping as well... in that case you need to replace the broken pipes.

if its level is not going down.
probably something mechanical between the pedal and the master cilinder (check for anything that may be loose or disconnected on the footwell

[dapinky]

Ooooh - I always hate it when there are no leaks - although clearly there is somewhere! (maybe!!!) - I say, 'maybe' because I am also assuming that the brake pedal is still attached to the piston which operates the master cylinder - it isn't unheard of for the 'R' clip (or splitpin) to fall off, and the clevis pin to work loose and fall out into the footwell.

I will make the assumption that you have checked all 4 corners of the car, and found nothing untoward (like a puddle of fluid underneath a calliper) - and likewise, there are no signs underneath the car along the chassis where the brake pipes run....

... that said, if it is a brake pipe, then any fluid leak may be onto the chassis/bodytub, so it is always having a look a bit later to see if it has dripped down to floor level....

....having got past all the 'obvious' potential leak spots, it only really leaves the master cylinder.

There are two possibilities that come to mind (but others may think of a different potential problem) - either the fluid is leaking into the servo by coming out of the back of the master cylinder, or the rubbers inside have failed and as the piston moves forwards, the fluid is getting past the seals and taking up the space where the seal started from.

Either of these scenarios will require removal of the master cylinder and either replacing the seals, or simply replacing the whole unit.

Generally, if the fluid is getting into the servo, it will then make its way through the vacuum pipe into the inlet manifold and be burnt off - this will give you a cloud of white smoke from the exhaust.

When you say that the pedal goes to the floor, does it come back up again when you take your foot off, or stay down? If you pump the pedal, do you get any braking effort? If you pump it a few times, does the fluid level then drop in the reservoir or stay the same? If it drops, then fluid is going somewhere, if it doesn't, then the seals have failed and the movement of the piston is doing nothing to the hydraulic bits.

Can you get someone to press the pedal whilst you watch the cylinder to see if you can see/hear/feel anything moving?

Edit - Joao beat me to it with his reply, but we're both thinking along the same lines. (no pun intended).

[Graaf]

Thanks for the comments guys,

I have pumped and pumped the pedal and their is no evidence of leaks anywhere.

The pedal returns on the spring.

I would hope that it’s not the servo or master cylinder as both were replace by the previous owner.

I’ll have a look at the mechanical side tomorrow and get someone to pump the pedal whilst I check.

Thanks again.

[Graaf]

Right Chaps.........

1. I've checked in the drivers foot well and the brake pedal is still connected to the wire which I assume connects it to the master cylinder.

2. The pedal comes up after being pressed.

3. Pumping the pedal gives no noticeable braking.

4. There appear to be no leaks in the pipework - no drips or little pools of brake fluid.

5. I have had someone press the brake pedal numerous times and can feel some movement in the master cylinder - so I assume all is connected.

6. There is no white smoke from the exhaust at start up.

7. The master cylinder reservoir appears to have gone down about and 1/8 th of an inch.

Can i take it that from the above it must be a fault on the master cylinder although it was fitted new by the previous owner approximately 4yrs ago?

If it is the master cylinder, does anyone know what car it is from - I know sjs have a replacement but would like to get it cheaper if possible

Lastly how difficult is it to replace/service the master cylinder for someone who is OK with big mechanical things but somewhat nervous where brakes are concerned - don't want to have fluid squirting everywhere?

Thanks again

[Tuga2112]

[quote="Graaf"]

7. The master cylinder reservoir appears to have gone down about and 1/8 th of an inch.[quote]

I'd suggest pump until liquid appears on the floor

[Fredjohn]

Fault sounds very similar to mine 12-18 months ago.
I bought SJ's replacement MC rather than the Lotus one he also sells (sold).

Resolved my soft pedal issue completely. Also like you I could find no leaks anywhere, not even around the MC and pedal.

Did it myself. Awkward job, especially undoing the 4 brake pipes from the MC. I used open ended ratchet spanners as well as multi sided open ended ones.

But it's easier than having to replace the servo.

PS some owners have fitted a different diameter MC to change the brake feel and response. Search on this site somewhere for choices and reasons. Usually associated with upgraded calipers. I stuck with standard MC even though I have upgraded claipers front and rear.

[Graaf]

Thanks, I think that I’ll bite the bullet and order a new mc and get it over with

[Tuga2112]

if fluid is disappearing from the reservoir is must be going somewhere. and being a closed circuit. the only way it can disappear is via a leak.

I Would be bleeding all corners before spending any money on anything.

my 4runner was stopped for nearly a year. when i started it again. the clutch wouldnt budge at all. and there was no signs of a leak.
when pumping i noticed the slave cilinder didnt move. so. bleed it. and everything is workig now..

a slow leak would not show the fluid on the floor, but would be enough to allow enough air to give you no braking effort while the pedal moves.

[epipete]

I'm following this with great interest.

I had exactly the same symptoms on starting up yesterday after a protracted period of being parked up.

There is no evidence of leakage at any of the corners and so although I have to give it more attention I'm fearing the worst

So, from reading the above Fred John raises the spectre of the Servo being at fault, but if so why? And how would you determine if it's the Servo or the Master Cylinder?

And the other question regarded what alternative units are available from which supplier/car?

Several years ago there was a lot of discussion on using a different but comparable master cylinder which gave a greater advantage - does anyone recall the topic?

[RonR]

I think it was on this thread which started in 2013.

However there was some discussion about whether the BMC could move enough fluid to cope with brake upgrades or when 1 circuit failed.
I'd read the whole thread before deciding to go for it.

[Fredjohn]

Pete
Although I mentioned the servo, given there is no white smoke coming from the exhaust to indicate burning off of brake fluid, my suspicion would be focused on the MC not the servo.
Similarly there seem to be no leaks, so his and possibly your condition replicate mine: a worn MC.
I was happy to use SJ's replacement.

PS this posted itself despite system saying ''error''.

[Saltire]

Edited to remove double posting

[Graaf]

Well, I’ve bled all 4 corners and got huge amounts of air out of the front offside calliper.

Took the car out for a brief spin and seems ok. Next dry day I’ll try again.

[Graaf]

Update.........

I have now bled all 4 corners.

Took it for a short drive to ensure all well and had no problems.

Took it for a drive today and the 'BRAKE' warning light came on intermittently.

I have checked the handbrake and that switch is OK and checked the brake fluid and it doesn't seem to have gone down.

Any suggestions???????

Thanks

[dapinky]

The intermittent warning light is usually caused by the fluid level in the reservoir being too low and it sloshing about as you drive. Because the reservoir has 2 chambers (front and rear) albeit they are actually joined, it isn't unusual to see fluid up to the line and think there is enough in there.
I'd suggest checking with the car on a flat bit of ground, and pouring a little more fluid into the tank (if it will take it!).

[Tuga2112]

make sure you tightened both bleed nipples and feed lines on all corners. if those fasteners are a little under torque they sometimes let air in in minute amounts that you wont notice if you drive it regularly, sometimes changing the copper washers in the feed lines is enough to stop a leak.

also. this is a less likely scenario. but bleed nipple threads may be damaged. which the advisable approach to correct is changing the caliper body... however a temporary solution is PTE tape in the threads... depending on how badly the threads are damaged.

[Graaf]

I’ll give those suggestions a go, thanks.

[Graaf]

I have decided to replace all of the brake fluid.

Brake warning light has gone off and all seems good but I’ve not had the chance to do many miles yet. I’ll make up for it when I get back from holiday.

Thanks again for all the help.

[Tuga2112]

I have decided to replace all of the brake fluid.

Brake warning light has gone off and all seems good but I’ve not had the chance to do many miles yet. I’ll make up for it when I get back from holiday.

Thanks again for all the help.

yes do many miles. thats the most important thing about owning an elan.

Ive measured my vehicles costs based on miles per pound.
the way to justify owning an elan is to do a lot of miles, because regardless of driving it everyday or only for 6 weekends a year. your gonna find yourself with the same costs in repairs.