leaking brake bomb?? S2 avant

[stevenEK9]

hopefully someone can help with this.............


for a while the car has flashed up the "fault in brake system" light on the dash at startup (( ! )) which goes out after a while

didn't think anything of it

recently was out driving and smoke started pouring out from under the bonnet, obviously first thought being oh ****!!!!!! all gauges reading normal so pulled over and let it cool

some form of leak which was hitting the exhaust and causing the smoke

whole way home the steering felt low on fluid and groaning a bit, so made me think that it was a steering fault


although today had more of a read into it and noticed that the warning light is brake related and the "brake bomb" runs off the PS system

this could explain why when looking for a leak the only leak i can see is fluid dripping from the underside of the brake master cylinder



so question is, would failure of the brake bomb cause enough of a lack of pressure in the PS system to cause the above? any help is massively appreciated

cheers

[Monkeymagic]

No it would appear you have low fluid due to a leak. The bomb only applies positive pressure intil the pas pump gets the system up to pressure or in the event of stalling etc. Just check the pipes and unions to find the leak....

[Michael S2]

Is it losing power steering fluid or brake fluid?

[stevenEK9]

It isn't brake fluid that is dripping from under the brake master cylinder, it only leaks once the car has been running for a bit

As mentioned when you turn the wheel it feels like the rack is low on fluid - however with the engine off the PS fluid level is between min and max

It was just after reading up on the brake fault warning light today that made me think the brake bomb could be at fault

No obvious leaks from the rack or unions - only leak i could see was from underside of brake MC, hopefully get another look tonight, it's very very frustrating

The pump is a bit noisy and will be looking to replace this soon also, but a faulty pump wouldn't cause a leak at the back of the engine bay.....

[Michael S2]

Sounds like a small leak is causing your problems. My bet is the hose from the rack to pump is split near the rack. Might only be a small leak which is why your levels still seem ok.

I had the smoke under bonnet scenario earlier this year and turned out to be this hose.

[Monkeymagic]

It only takes a small drop in the levels to affect the pas pump.

[bluequattro]

Are the pas pipes kinked?
My "ace mechanic" put one back wrong when he took rad out of my tdi for cam belt change
He fitted pas pipe in the hooked bracket wrong
Mrs said a few days later it was making a funny noise and the steering felt wrong
The kinked pipe(low pressure) wouldn't let fluid through
Moved/unlinked pipe and all was well
It may be pressure not returning on yours that s found a weak pipe in the system, they usually split where you can't see them!

[stevenEK9]

Thanks for the replies, had a look at the car tonight and can understand the system a bit better

Once running the fluid level drops below the pickup point in the resevoir - hence there is no leak now as the pump is effectively dry running

Going to top it up, run the car and check for a leaky pump to rack line


Got spare lines and rack i picked up on here the other week so can swap out whatever is dud

Cheers

[rynaqui]

Make sure to use genuine G004000!

[stevenEK9]

Yeah i used the correct hydraulic fluid

What a faff and a half!!! Replaced the pump to rack hose tonight and it is now leak free!!!!!

I think the brake fluid 'leak' was just water from the car sitting as that all seams fine

Just an inner cv to do and the car will be 110% again


Cheers again for the input

[Greg_S]

Another possibility is the valve in the bomb is knackered so it is being filled with pas fluid and rather than retaining that pressure for the event of stalling etc it just gets returned to the reservoir when the engine is switched off