brake pedal sinks while steering is slightly turned

[mrhaz]

As title says the pedal sinks while steering is slightly turned. I had it in for a mot all the brakes were checked nothing seemed wrong apart from the handbrake the guy said it needs adjusting any ideas cheers.

 

[stu1873]

You checked the brake fluid levels in the reservoir?

 

[mrhaz]

You checked the brake fluid levels in the reservoir?

Fluid level is fine mate when I open the cap I can see the fluid just by the line its not overloaded near max.

 

[AdamB]

Double check the vacuum line that goes to the servo and make sure that's not split. When you turn the steering wheel (without pressing the brake and stationary) does the engine rev up a little? It should rev slightly as it's under more load.

 

[mrhaz]

Double check the vacuum line that goes to the servo and make sure that's not split. When you turn the steering wheel (without pressing the brake and stationary) does the engine rev up a little? It should rev slightly as it's under more load.

Haven't tried it but when the steering is turned full it does change the tone of the engine so I'm guessing that's when its putting load on engine. Don't think the revs go up.

 

[mrhaz]

Double check the vacuum line that goes to the servo and make sure that's not split. When you turn the steering wheel (without pressing the brake and stationary) does the engine rev up a little? It should rev slightly as it's under more load.

^^^ this mentioned above is this what you ment? And wheres the vacuum line that goes to servo thanks

 

[AdamB]

If the engine tone changes that's fine.
The vacuum line, just look at the servo, there's only 1 hose that comes off it, it will go to the inlet manifold. It shouldn't have any T-pieces or joins etc. If you want to test to see if its split, get some washing up liquid and water in a spray bottle and spray on the hose, if you see bubbles it has a leak.

 

[mrhaz]

If the engine tone changes that's fine.
The vacuum line, just look at the servo, there's only 1 hose that comes off it, it will go to the inlet manifold. It shouldn't have any T-pieces or joins etc. If you want to test to see if its split, get some washing up liquid and water in a spray bottle and spray on the hose, if you see bubbles it has a leak.

Thanks for getting back I will spray water over it and check it out? But if its losing brake fluid then that does mean there's leak in system will I need a new servo or cylinder then?

 

[Eddie Z]

I don't think you can check for leaks in the vacuum line by using washing up liquid, because it would basically just suck the liquid in the crack and you wouldn't get any bubbles. That works for pressurized lines or tires though. I've seen someone use smoke (eg. cigarette) to find leaks in vacuum line. You can find examples in google.

Based on your description, I would guess that you have a small leak in the brake booster itself, that causes it to loose vacuum. Easy way to check for vacuum leak is to press the brake pedal while starting the engine. The pedal should sink when the booster gets vacuum.

 

[AdamB]

I was going to mention the cigarette thing, or E cigs as they give of plenty of vapour :lol:

It's not a brake fluid leak you have, assuming the fluid level is fine on the master cylinder reseviour.

Deffinately check the servo for operation by doing what Eddie said with starting the engine. I had a look today on my own engine, the vacuum pipe which comes from the servo isn't very long at all and goes into a metal joiner where its clamped on.

 

[mrhaz]

I was going to mention the cigarette thing, or E cigs as they give of plenty of vapour :lol:

It's not a brake fluid leak you have, assuming the fluid level is fine on the master cylinder reseviour.

Deffinately check the servo for operation by doing what Eddie said with starting the engine. I had a look today on my own engine, the vacuum pipe which comes from the servo isn't very long at all and goes into a metal joiner where its clamped on.

I will check that thanks and will get it to garage. Anyway if car is running and stationary when pressure is applied on the brake pedal should it be sinking or not? Pressure as in pressed excessively. The brakes do make a funny creaking sound when I'm driving at slow speeds and brake from front discs. I did put in mtec discs and ferodo 2500 pads 10 months back sorry for the long post cheers.