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[P6UL K]

During the drive home last night I noticed something was amiss with the brake pedal and brakes, The brakes were still working fine but I noticed that the pedal was slowly sinking away under my foot when I was applying pressure although the car was still slowing at a good rate. Then during the drive to work this morning first roundabout I approach and the pedal just drops away under my foot completely and the next thing I know I'm trying to push my foot through the bulkhead!!

Can the brake servo have possibly given up the ghost?! As much help as possible would be great so I can pinpoint a few things to investigate after my shift today as I need the car to get to from work!

[JamesV6CDX]

What's the fluid level like?

[P6UL K]

I'll have to do get back to you on that one James as I'm currently driving to Brighton for a delivery

[Nick W]

Servo failure is very rare(it's a very simple device), and makes the pedal hard.
You're looking for a fluid leak, have a quick look at the calipers and the hoses that lead to them.
But the most likely cause is a faulty master-cylinder.

[Andy B]

Servo failure is very rare(it's a very simple device), and makes the pedal hard.
You're looking for a fluid leak, have a quick look at the calipers and the hoses that lead to them.
But the most likely cause is a faulty master-cylinder.

That'd be my guess too

[P6UL K]

What's the fluid level like?

Completely empty!

[JamesV6CDX]

Get hunting for the leak, then

[P6UL K]

I have!

All 4 calipers and their flexi hoses are dry as a bone with no sign of any fluids inside the rims or on the ground.  AFAIK there aren't any other rubber brake hoses are there?

[Marks DTM Calib]

Has some Muppet fitted non vented discs to the rear?

[Andy H]

It is possible for a seal or seals to fail in the master cylinder and allow fluid to get sucked into the servo. From there it  passes into the inlet manifold and disappears in a puff of smoke (so doesn't leave any puddles as evidence). Never heard of it happening to an Omega though 

[05omegav6]

Is this the diesel one or the 3.2

[henryd]

I have!

All 4 calipers and their flexi hoses are dry as a bone with no sign of any fluids inside the rims or on the ground.  AFAIK there aren't any other rubber brake hoses are there?

It doesn't have to be a flexy hose that's failed,steel pipes can and do corrode and burst

[05omegav6]

I have!

All 4 calipers and their flexi hoses are dry as a bone with no sign of any fluids inside the rims or on the ground.  AFAIK there aren't any other rubber brake hoses are there?

It doesn't have to be a flexy hose that's failed,steel pipes can and do corrode and burst

Don't ignore the clutch... although, it's designed to fail long before the brakes do, making it almost impossible to drive before the brakes fail

If the clutch works, you still have fluid in the system, the level in the brake reservoir is different to the level under the cap...

[P6UL K]

Has some Muppet fitted non vented discs to the rear?

I'll have to let you know in the morning Mark

[P6UL K]

Is this the diesel one or the 3.2

The thorn in my side mate - the hearse.

[P6UL K]

I have!

All 4 calipers and their flexi hoses are dry as a bone with no sign of any fluids inside the rims or on the ground.  AFAIK there aren't any other rubber brake hoses are there?

It doesn't have to be a flexy hose that's failed,steel pipes can and do corrode and burst

TBH I'm not sure anything has burst as there is still 'very' minimal braking at about 5% 

[05omegav6]

Is this the diesel one or the 3.2

The thorn in my side mate - the hearse.

Right, so manual 2.2dti, should have solid rears, but if they've been upgraded at some point, the calipers will be marked with 42, same as the 3.2

[P6UL K]

Why would that be of any relevance chap?

[05omegav6]

Why would that be of any relevance chap?

Solid discs in vented calipers allows the pistons to escape, causing fluid loss, hence Marks post

You're already having vacuum issues with that car, so master cylinder/servo looking likely... and being a diesel, the cause/solution may be different to the V6.

As said, the clutch is fed by the brake reservoir, so fluid loss would soon stop you changing gear, again, if the clutch works, it points to a vacuum/servo problem...

[Nick W]

Sudden fluid loss with no obvious  external leak is classic master-cylinder failure.
The brake fluid has leaked into the servo, which is why you can't see it.

Yet.

Eventually, it will drip down the brake pedal and onto the carpet, so that's probably worth a look.

[P6UL K]

Why would that be of any relevance chap?

Solid discs in vented calipers allows the pistons to escape, causing fluid loss, hence Marks post

You're already having vacuum issues with that car, so master cylinder/servo looking likely... and being a diesel, the cause/solution may be different to the V6.

As said, the clutch is fed by the brake reservoir, so fluid loss would soon stop you changing gear, again, if the clutch works, it points to a vacuum/servo problem...

I'll check that out tomorrow but I doubt anyone would bother with that kinda upgrade on this Omega 

[P6UL K]

Sudden fluid loss with no obvious  external leak is classic master-cylinder failure.
The brake fluid has leaked into the servo, which is why you can't see it.

Yet.

Eventually, it will drip down the brake pedal and onto the carpet, so that's probably worth a look.

This is what I suspect and have been advised, can I just replace the master cylinder or do I need to replace the servo also? I'm guessing I can't leave it with brake fluid in it...? :-/

[Nick W]

You're unlikely to need to replace the servo, just remove all the brakefluid from it. A large syringe works well, or you could soak it up with lots of rag/tissue.

[P6UL K]

You're unlikely to need to replace the servo, just remove all the brakefluid from it. A large syringe works well, or you could soak it up with lots of rag/tissue.

Good stuff, I'll get onto Vauxhalls in the morning then! Hopefully this will sort my boost issues too but I doubt it 

[Andy B]

....
Good stuff, I'll get onto Vauxhalls in the morning then! Hopefully this will sort my boost issues too but I doubt it 

I'd expect the price of A N Other master cylinder to be favourable than that of the main dealers 

[P6UL K]

That's a fair point Andy and one which I will look into but I have trade card so no doubt will save me a fair bit 

[Andy B]

That's a fair point Andy and one which I will look into but I have trade card so no doubt will save me a fair bit 

Trade Club Card is mainly for service items, you might get it at 'Trade' if you're lucky.

An OOF breaker might be your best bet. 

[Nick W]

A secondhand brake mastercylinder?

Count me out.

[P6UL K]

Nah I'll buy new, get good discount on most things from Vx with the trade card, failing that I get trade at a few motor factors. And Halfords 

[Andy B]

A secondhand brake mastercylinder?

Count me out.

Come off it ...... do you need a hand down from your high horse?  ? It comes under the same heading as part worns when you buy your 'new' car ..... we don't change all four tyres (Chris might  ) What's the problem?

[Andy B]

Nah I'll buy new, get good discount on most things from Vx with the trade card, failing that I get trade at a few motor factors. And Halfords 

I doubt that many motor factor will hold stock of a part for a 10 yr old car ....... & I'd be interested to know how much the dealers will charge. I know they (the dealers) don't do seal kits for them.

[chrisgixer]

Would brake fluid in the servo eat the rubber bladder/components?

[Andy B]

Would brake fluid in the servo eat the rubber bladder/components?

Possibly 
I seem to remember being recommended to replace master cylinder complete with a servo ....... it was a long time ago now & I can't remember why.

[chrisgixer]

Would brake fluid in the servo eat the rubber bladder/components?

Possibly 
I seem to remember being recommended to replace master cylinder complete with a servo ....... it was a long time ago now & I can't remember why.

I'd hope they'd design in some oil/bf proof components given the possible failures. But I'm not sure I could trust it personally.


I must say though, at the first sign of a sinking pedal, I'd be checking for faults pretty sharpish.

Anyway, we're surmising until Paul reports back the fault.

[Andy B]

....
I must say though, at the first sign of a sinking pedal,  ....

In the same situation 30 yrs ago in my MKIII Cortina, my first thoughts were ............. OH opps!!!!! and then reached for the handbrake.  Fortunately I was only going slowly. 

[chrisgixer]

Oh that old thing, is there any point on an auto? Think I'd be too busy crapping me pants tbh

[terry paget]

Interesting thread. I don't understand how Paul got 5% braking with no fluid. If I had lost all my fluid and could not see the leak, I would have put in more fluid and  waited to see it emerge somewhere. I have known steel pipes rust through with pinholes and slowly lose fluid. But, as Al said, clutch should fail first, and fluid level warning light come on. Did the light come on, Paul?

I have known brake failure; master cylinder seal failure (Vw Passat), rear cylinder popping out (Peugeot 505) and copper brake pipe fracture (Omega); also slow fuel loss from pinhole in steel pipe, Peugeot 505 again.

Not sure if the clutch would fail; fluid in the vertical pipe might suffice to operate  clutch.

[05omegav6]

Had fluid loss on my Seat, caused by clutch slave failure, similar set up to the Omega. Once the fluid dropped below the clutch feed the pedal simply fell to the floor

Have also experienced vacuum/fuel pump failure on a 1.9tdi Superb, that made the brakes almost non existent, temporarily cured by adding oil to the vac line from the servo to the pump

[Andy B]

There are baffles in the master cylinder to retain fluid in the various sections of the brakes ie split (front/rear) brakes system likewise with the clutch. Not sure how there's a complete loss of fluid 

[Shackeng]

Interesting thread. I don't understand how Paul got 5% braking with no fluid. If I had lost all my fluid and could not see the leak, I would have put in more fluid and  waited to see it emerge somewhere. I have known steel pipes rust through with pinholes and slowly lose fluid. But, as Al said, clutch should fail first, and fluid level warning light come on. Did the light come on, Paul?

I have known brake failure; master cylinder seal failure (Vw Passat), rear cylinder popping out (Peugeot 505) and copper brake pipe fracture (Omega); also slow fuel loss from pinhole in steel pipe, Peugeot 505 again.

Not sure if the clutch would fail; fluid in the vertical pipe might suffice to operate  clutch.

This is what I could not follow, unless the warning system is fubar.

[05omegav6]

There are baffles in the master cylinder to retain fluid in the various sections of the brakes ie split (front/rear) brakes system likewise with the clutch. Not sure how there's a complete loss of fluid 

Clutch is fed straight from the reservoir by way of the spigot on the side of it, manual and auto using the same reservoir 

[Andy B]

There are baffles in the master cylinder to retain fluid in the various sections of the brakes ie split (front/rear) brakes system likewise with the clutch. Not sure how there's a complete loss of fluid 

Clutch is fed straight from the reservoir by way of the spigot on the side of it, manual and auto using the same reservoir 

I know. But it would be a crap design if a failed clutch slave cylinder caused a complete brake failure. There's a baffle inside the reservoir such that if the slave leaks you still maintain a brake fluid level for the brakes and as above a leak on front or back of the brakes maintains a fluid level for the remaining half of the brake system ie split braking system.

[Andy H]

The spigot is about 1/3 up the side so a faulty clutch still leaves 1/3 in the rear compartment. The baffle is higher again so the front compartment should remain about 1/2 full.

The dual circuit master cylinder usually has two pistons, the first one is connected to the brake pedal via the servo. The second one is further down the bore of the cylinder. Pressing the pedal pushes the first piston which forces brake fluid down one set of brake pipes but also makes the second piston move and feed the second circuit.

If the seals on the first piston fail then the pedal will go half way to the floor before the piston makes contact with the second (floating) piston to give some braking from the second circuit.

If the seals on the second piston fail you won't really notice any difference unless or until the seals fail on the first piston and you need the second piston to save you.

I think this is what happened to Paul - the floating piston seals were probably just good enough to stop the car once but not enough to stop the fluid leaking between circuits.

[Marks DTM Calib]

So time for some facts and reality.

1) the clutch take off is high up the side of the rest so failures there won't impact the brakes

2) its a twin circuit so master cylinder failure should only affect a pair of brakes, similar if it was an external seal failure

[05omegav6]

So time for some facts and reality.

1) the clutch take off is high up the side of the rest so failures there won't impact the brakes

2) its a twin circuit so master cylinder failure should only affect a pair of brakes, similar if it was an external seal failure

But fluid loss should result in clutch failure before brake failure if fluid loss is the issue

[Marks DTM Calib]

Fluid loss is likely to not affect the clutch at all unless it suddenly needs extra fluid (and clutches don't wear that quick)

[P6UL K]

I see a lot has happened while I've been at work! 

In short, yes the red warning light has come on on the dash but I took that for the pads were low as it's also on the info screen and the brakes were still working fine at the time.

Clutch is working fine and all gears engage as they should.

Since then the light seems to come and go but as I explained earlier the front brakes are running at a very low 5%ish! And from what Andy M has described the issue sounds just like that.  I rang Vx for a price on a master cylinder which came in at approx £230 with trade discount but I remembered I used a Co called Brake Engineering in Wrexham, I've spoken to them and for roundabouts £60 their going to strip and completely refurb my original master cylinder for me.

It's going to be NYD before I get to have a proper look at things - bloody winter days being so short!

[AndyRoid]

A secondhand brake mastercylinder?

Count me out.

Come off it ...... do you need a hand down from your high horse?  ? It comes under the same heading as part worns when you buy your 'new' car ..... we don't change all four tyres (Chris might  ) What's the problem?

As above really Nick, a secondhand master cylinder will either work or not...there is no inbetween.

Granted it could fail sooner than expected, but so could a brand new one.

[Marks DTM Calib]

Omega master cylinders are bullet proof so second hand is a viable option ( I recall there being three versions)

[P6UL K]

Had the car into the garage today to fix the brake issue which turned out to be........ A burst solid brake pipe hidden up above the rear beam!!!!

So had that repaired, new fluid and bled and the brakes are working a treat now and while they were there they fitted the only remaining part of the vacuum system that hadn't been replaced - the vacuum pump.  Non boost issue still remains!! Ugh!

[05omegav6]

At least the brakes work again

[P6UL K]

With no turbo the wingmirrors create enough drag not to need brakes anyway   

[chrisgixer]

Any cause identified? Rubbing or corrosion maybe?

[P6UL K]

I've been informed that it was just down to corrosion mate.

[AndyStobbs]

The plastic clips hold moisture against the pipe. The pipes always fail where there has been a clip.

[05omegav6]

I've been informed that it was just down to corrosion mate.

Not long been MoTd though any advisories then?

[P6UL K]

I've been informed that it was just down to corrosion mate.

Not long been MoTd though any advisories then?

Nope, nothing! Came back clean as a whistle!

[henryd]

I've been informed that it was just down to corrosion mate.

Not long been MoTd though any advisories then?

Nope, nothing! Came back clean as a whistle!

Did the tester have a Labrador by chance

[aaronjb]

Did the tester have a Labrador by chance

Always annoys me when they're hitting my car with their white stick..

[terry paget]

Had the car into the garage today to fix the brake issue which turned out to be........ A burst solid brake pipe hidden up above the rear beam!!!!

So had that repaired, new fluid and bled and the brakes are working a treat now and while they were there they fitted the only remaining part of the vacuum system that hadn't been replaced - the vacuum pump.  Non boost issue still remains!! Ugh!

My Omega has not got a vacuum pump. It gets its vacuum from the inlet manifold, with  A reservoir or two..

[P6UL K]

Had the car into the garage today to fix the brake issue which turned out to be........ A burst solid brake pipe hidden up above the rear beam!!!!

So had that repaired, new fluid and bled and the brakes are working a treat now and while they were there they fitted the only remaining part of the vacuum system that hadn't been replaced - the vacuum pump.  Non boost issue still remains!! Ugh!

My Omega has not got a vacuum pump. It gets its vacuum from the inlet manifold, with  A reservoir or two..

Is it a diesel tho?

[terry paget]

Had the car into the garage today to fix the brake issue which turned out to be........ A burst solid brake pipe hidden up above the rear beam!!!!

So had that repaired, new fluid and bled and the brakes are working a treat now and while they were there they fitted the only remaining part of the vacuum system that hadn't been replaced - the vacuum pump.  Non boost issue still remains!! Ugh!

My Omega has not got a vacuum pump. It gets its vacuum from the inlet manifold, with  A reservoir or two..

Is it a diesel tho?

No. I did not not know diesel cars had vacuum pumps. Do all diesels have them? They must suck at some stage.

[aaronjb]

Had the car into the garage today to fix the brake issue which turned out to be........ A burst solid brake pipe hidden up above the rear beam!!!!

So had that repaired, new fluid and bled and the brakes are working a treat now and while they were there they fitted the only remaining part of the vacuum system that hadn't been replaced - the vacuum pump.  Non boost issue still remains!! Ugh!

My Omega has not got a vacuum pump. It gets its vacuum from the inlet manifold, with  A reservoir or two..

Is it a diesel tho?

No. I did not not know diesel cars had vacuum pumps. Do all diesels have them? They must suck at some stage.

All diesels with no throttle butterfly (that's 99% of them up to a few years ago) do, no butterfly = no vacuum as the engine is always sucking against an open ended pipe.

[terry paget]

Had the car into the garage today to fix the brake issue which turned out to be........ A burst solid brake pipe hidden up above the rear beam!!!!

So had that repaired, new fluid and bled and the brakes are working a treat now and while they were there they fitted the only remaining part of the vacuum system that hadn't been replaced - the vacuum pump.  Non boost issue still remains!! Ugh!

My Omega has not got a vacuum pump. It gets its vacuum from the inlet manifold, with  A reservoir or two..

Is it a diesel tho?

No. I did not not know diesel cars had vacuum pumps. Do all diesels have them? They must suck at some stage.

All diesels with no throttle butterfly (that's 99% of them up to a few years ago) do, no butterfly = no vacuum as the engine is always sucking against an open ended pipe.

Amazing. So what does the throttle pedal control?

[05omegav6]

Fuel delivery