hi need help from you, before i go to the stealers

basically it started about 2 weeks ago, after a cold start, when tried to apply brakes there was non!

when pumped up the car would stop eventually

brake pedal feels spongy, there is no biting point, with the engine on if i apply constant pressure the pedal will go right to the floor
with the engine off i can pump it a few times and it will become and stay solid

went to kwik-fit this morning and the told me it's the master cylinder broken, but after gooogling i've found on volvo's forum very similar problem being solved by vacuum pump replacement

any ideas before i go and part with my cash?

just to add: the problem seems intermittent

arti_abarth said:

... just to add: the problem seems intermittent

Click to expand...

This maybe of no value regarding your specific brake problem. But I read an article this morning that submitted salt from the roads is causing brake pad/disc & caliper problems - I think the solution was a good cleaning. I can find the article source if of interest(?)

----------------------
Croma II 1.9/16v 150hp

This is what elearn has about checking the vacuum pump:

Discharge the vacuum in the brake servo, with the engine switched off, by repeatedly pressing and releasing the brake pedal forcefully
Start up the engine without accelerating with the pedal depressed.
After a few seconds, check that brake pedal is operating in accordance with the increase in pressure due to the action of the brake servo.
Release the brake pedal and swith off the engine without operating the pedal again.
After about 10 minutes with the engine switched off, operate the brake pedal and check that when it is operated for the first time the extent it is lowered corresponds to the brake servo and that the operation becomes gradually harder.

From what you say it seems there is no vacuum.

This is from 2.4, let me know which you have and I will send you all the info I have, including vacuum pipe and non return valves.

The test I would try is this; with the engine off, pump the pedal until it becomes solid. Leave the car for a couple of hours then go back and see if the pedal is still solid. If it's not, either there is air in your braking system or the master cylinder is faulty (or both, as failure of the master cylinder seal at the servo end leads to air ingress).

From the description I'm struggling to see how the vacuum pump can cause this - if there's too much vacuum then the brakes will be over-servoed but effective; not enough and the pedal will be over-firm.

Hope you get it sorted, please let us know how you get on.

thank you all for your suggestions

well after much more reading and testing i came to conclusion that the problem is not intermittent, my brakes seem to work most of the time because croma has two independent braking circuits configured diagonally - front left wheel with right rear and front right with rear left. So my brakes are working 50% now

today i'll test my vacuum pump as per keithglos suggestion, and with another method - disconnecting vacuum pipe from the pump and checking for vacuum (found info HERE)

I would like to know where the non return valves are, so keithglos if you would be so kind and give some info it would be very appreciated

at the moment i think (and hope) that DoIDon'tI is right, because when i start the engine the brake pedal is going soft - so there is servo assistance - so there must be vacuum - I'm i thinking right?

the brake master cylinder is only £74 so i can live with that, just wondering how much it will be to fit

i'm also wondering what have caused the failure on a three and a half year old car, 7 months out of warranty :bang:

also if anyone is interested i found a great pdf guide on everything about brakes HERE

arti_abarth said:

when i start the engine the brake pedal is going soft - so there is servo assistance - so there must be vacuum - I'm i thinking right?

Click to expand...

Yes.

arti_abarth said:

thank you all for your suggestions
I would like to know where the non return valves are, so keithglos if you would be so kind and give some info it would be very appreciated

Click to expand...

It now seems more likely that the problem could be master cylinder. A search for vacuum pump problems revealed just about nothing. The alfaowner.com is pretty good for for this type of trouble, but nothing.
This indicates that it's very rare (just as well) for the vac pump to fail.
I have put a couple of pages from eL into a word doc (147Kb), if you give me an email address I will send it, but it doesn't look very useful to me.

When was the brake fluid last changed? If in doubt change the fluid. (even if the last service agent claims to have completely change the fluid - some unscrupulous garages have been known to just suck the reservoir almost dry and top up with fresh fluid.)

For the sake of an hour+ and a litre of brake fluid I would completely change the fluid. Bad brake fluid can create all sorts of strange issues in modern brake systems.

i'm not sure when the fluid was last changed, should be every two years
i bought the car with 45k on the clock and 2,5 years old, there is no docummentation what was done during services.

anyhow i got the problem diagnosed as clutch master cylinder leaking fluid - a bit strange to me because i haven't lost any fluid and i don't have any problems with my clutch

i'm getting it done on Tuesday, hope new clutch master cylinder will fix it, they will renew the fluid aswell

Ah, daft question (which I don't know the answer to as mine's an auto) - do the clutch and brakes share reservoirs? Might explain it. Either way, hope you get sorted out.

DoIDon'tI said:

Ah, daft question (which I don't know the answer to as mine's an auto) - do the clutch and brakes share reservoirs? Might explain it. Either way, hope you get sorted out.

Click to expand...

no it's not a daft question, that's why i authorized this to be replaced, anyways today it turned out that clutch master cylinder is not causing the problem but they still say it's leaking

they will investigate further, i'll keep you updated