Vauxhall Vectra 2.5l GLS 1997 Petrol.
Can anyone advise why the brake fluid level (master cylinder) should rise over the months. I have noticed this particularly over the last couple of years but it may have done this since the car was new. I have to syringe out every few months to stop the fluid leaking through the cap.
Not sure if its related but the brake pedal slowly sinks to the floor if I push it down after braking to a stop (eg at traffic lights).
Last year Vauxhall 1)Bled & exchanged the brake fluid several times 2) changed the master cylinder 3) changed the servo 4) changed front brake pads - all under warranty. They then gave up & said the braking was "satisfactory". However there wasn't any improvement & the pedal still sinks slowly down when pressed, although normal braking is satisfactory & it passed an MOT since. ANY IDEAS FOR EITHER OR BOTH OF THESE PLEASE???
Thanks
Richard
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Apparent rise in brake fluid level is usually found to be caused by water somehow getting into the brake master cylinder.I've dealt with several Astra Mk3s with this problem where water runs off the cover at the base of the screen and on to the cylinder reservoir.When the brakes are applied it gets drawn into the brake fluid via the cylinder vent.Try covering the whole master cylinder with a plastic bag and see if there's still any rise in fluid level.
AFAIK if braking performance is OK,the pedal sinking problem you describe is an acceptable condition.I don't think the two concerns are connected,but obviously water getting into the brake system will be doing a lot of damage.You should have the system completely flushed out at the very least.
David Davies (Tune-Up Raglan)
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Can't see that it makes any difference but the fluid reservoir is also for the hydraulic clutch on the Vectra.
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I think that you will find that Astras were subject to a recall to provide a mod to prevent water ingress.
See www.honestjohn.co.uk/forum/post/index.htm?v=i&t=67...7
My view is that if pedal sinks to the floor it is indicative of a potential and serious problem that must be sorted. Braking performance is irrelevant. Use of the car should be discontinued immediately.
pmh (was peter)
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Richard,
I would get this sorted sooner rather than later. Your brake pedal should not sink at all when you've got your foot on it and the brakes are firmly applied. Obviously I don't need to point out that one day you might need to stamp on the brake pedal in an emergency and it could sink straight to the floor. God forbid that should ever happen, but you can never be too careful where brakes are concerned. I can't suggest what is wrong, but David Davies suggestion of water in the brake fluid certainly sounds plausible.
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Is it possible to check the brake fluid for water content? Boiling point or something?
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Most tyre/exhast places that offer 'Free' brake check should be able to do this.
Mark
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Water ingress hadn't occurred to me as a reason for the fluid level to rise by itself but it makes sense now that it has been pointed out.
The brake pedal slowly sinking to the floor could be caused by a failing (soggy) primary seal in the brake master cylinder. That is, when the pedal is pushed down fairly hard, the sudden high pressure makes the cup-like seal expand tight against the cylinder wall and so the brakes work OK, but holding the car gently on the footbrake doesn't fully expand the seal and the fluid slowly escapes past it (but is still retained within the system by the secondary seal). A bit like a worn-out bicycle pump where a sudden hard push is required to get the cup to expand against the bore.
I appreciate that the master cylinder on the Vectra has been changed but perhaps the seal problem is caused by the water in the fluid and this has caused the new master cylinder to fail in the same way as the original?
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Dizzy is bang on with the reasons for the pedal going down. Sounds like the secondary seal too if it goes all the way to the floor eventually. Replacement master cylinder required. Mike
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Hi Richard, I have come across this problem on a Rover which turned out to be engine coolant being dragged in through leaking (water heated) inlet manifold seals and then being drawn through the servo vacuum pipe through worn seals in the master cylinder. It took a while to work out where the extra fluid was coming from as I didn't have a brake fluid tester.
As for pedal travel, my advice is to stop driving the car immediately! Brakes work because fluid is incommpressible - the principle behind hydraulics. If the pedal sinks then you have either a fluid leak somewhere, trapped air caused by high water content that vapourises causing airlocks OR a flexible brake pipe that is ballooning under pressure. Try clamping off the flexible brake hoses then trying the pedal. If it stays firm then the problem is somewhere in the clamped off hoses. Release one at a time until the pedal goes soft. That should be the suspect hose. If none of this makes any difference then suspect the master cylinder.
Hope this helps, and please don't be tempted to use the car until it's been fixed.
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Hi Richard, I have come across this problem on a Rover which turned out to be engine coolant being dragged in through leaking (water heated) inlet manifold seals and then being drawn through the servo vacuum pipe through worn seals in the master cylinder.
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Sorry Agent K but I think you've been fed some misinformation by whoever diagnosed your problem, i.e. how does the coolant that's leaked into in the servo get to the seals in the master cylinder ?
A totally impossible scenario IMO, Somebody correct me if I'm wrong but IIRC the servo is connected to the master cylinder by a mechanical likage, fluid and vacuum transfer is not possible.
The Rise in fluid level is, via the cap as mentioned previously and whilst the pedal slowly sinking RIGHT TO THE FLOOR is probably leaky seals, slow sinkage of the pedal (not to the floor) is quite normal on some cars, whilst stood, as the vacuum in the servo drops.
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>>A totally impossible scenario IMO, Somebody correct me if I'm wrong but IIRC the servo is connected to the master cylinder by a mechanical likage, fluid and vacuum transfer is not possible
To put it this way,not one I have come across in all the years I have worked on them and owned,has this happened to, so fully agree...However coolant leak in inlet manifold effects the running of engine and has no effect AFAIK on brakes
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Steve
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I agree - the direction of airflow is from the servo *to* the manifold - water in the manifold won't get into the brake reservoir.
Number_Cruncher
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its only a one way valve ,they can fail ,see the merc thread earlier this week ,its exactly what i suggested ............cant remember the outcome mind?dont think there has been one?
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Ah! - it isn't the one way valve that determines the direction of flow! It is because the manifold is at lower pressure (or higher vacuum if you prefer) than the servo. The one way valve is only there to hold the vacuum in the servo while the throttle is open.
Even if the one way valve fails, while there may be temporary flows in the reverse direction, the aggregate air flow is towards the manifold.
I can't imagine any significant amounts of material finding their way into the manifold - all the servos I've ever looked into have been perfectly clean except for the cases where the master cylinder has failed.
Number_Cruncher
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Sorry Agent K but I think you've been fed some misinformation.....
I should point out that this thread is over 3 yrs old, and also that Agent K hasn't been seen in all that time either.
DD.
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Sorry to disapoint DD but Agent K is very much alive. Please read my latest thread on this subject. Briefly, coolant was leaking in such a way from the inlet manifold that said coolant was being forced into brake servo via servo to manifold vacuum hose. It was a combination of worn engine, worn master cylinder and bad coolant leak that caused this very unusual and rare problem. I have only seen it once in 17 years, which goes to prove that one should never assume anything - especially when it comes to cars.
Regards
Agent K
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Sorry to disapoint DD but Agent K is very much alive.
Well, when I posted my comment, you (as in Agent K) hadn't been seen in all that time.
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Sorry to disagree but when we carried out an automotive autopsy on the braking system, we found that coolant WAS being drawn into the brake fluid lines via the water cooled inlet manifold. We also had a Rover technician back us up as he has seen this happen only once before in a very long career. As I stated in my original posting back in 2003, I warned the driver NOT to drive the vehicle. The car that I had worked on and spotted coolant being drawn in to the brake circuit did have a very worn master cylinder. I have worked on all sorts of makes and models (professionally I might add) and this strange incident sticks in my menory as I have only seen this happen once. The reservoir , was protected from water ingress and we even got to the stage of adding a dye to the coolant and watched (including the Rover Tech) as coolant containing the dye slowly showed up in the brake master cylinder reservoir.
As a car mechanic with 17 years experience AND a healthy understanding of engineering principles, I never ignore the 'impossible'. I am open minded and to this day, have never stopped learning. Every mechanic will occasionally experience baffling symptoms on a car. I also have experienced numerous incidents of rising fluid levels on Astras due to poor drainage. I will add that on the Rover, the brake fluid reservoir and master cylinder were protected and the installation was better thought out than the vauxhall Astra set up.
I continue to post on this site but have not used Agent K handle since now when this thread came up.
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Dear Richard,
I have a 1991 Cavalier and have exactly the same problem of my brake pedal sinking down after braking to a stop.
Did you ever get your problem resolved?
Thanks,
Cavalier99
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I don't think you will get an answer, he hasn't posted here for over three years.
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Perhaps his brake pedal went to the floor once too often...
As mentioned above - if the pedal continues to sink under steady pressure, rather than stopping at a certain point, the master cylinder is at the top of the list of suspects.
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Agentk. I am intrigued how coolant water was getting into the Brake system via the inlet manifold. There is not connection between the Manifold and the brake circuit other that the Vacuum used for the servo. Regards Peter
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>>I am intrigued how coolant water was getting into the Brake system via the inlet manifold
As am I ????
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Steve
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Sorry, forgot to ask what Rover this happened to??
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Steve
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Hi Peter, we found the coolant escaping from heated inlet manifold then being drawn via brake servo vacuum hose then into brake servo. Leak was so bad that servo was full of coolant which made its way into master cylinder. I have to add that the car in question was quite un-driveable. The owner had noticed that the brake fluid level had been rising but had not checked to see if the coolant level was dropping. To top it all, the servo one-way valve was faulty which in normal circumstances should not have allowed even a major leak into a braking system.
Like I mentioned in my last posting, myself and the Rover technician had not seen this symptom before and we suspect that it was a combination of a very knackered engine and some ill advised tinkering by the owner. Since then, I have never seen this mechanical malady since, although I have seen several Vauxhall Astras with rain water ingress in the brake reservoir.
Andrew.
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Mmmm.....flying pigs come to mind.....
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Agent K,please specify the Rover you mentioned it happened to.
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Steve
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Amazing. No wonder the cost of bacon is so high. !! Regards Peter
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