Brake pedal whooshing sound.

[PeterH]

I've been having a bit of a search around for info on this, I'm sure some of you have had to deal with this before.
When I press the brake pedal, I have roughly an inch of movement before anything happens.
While the pedal is moving through that inch, I hear a whooshing sound.
Pressing the pedal further, the pedal feels good, brakes work perfectly and the P38 pulls up with no trouble at all with no sounds.
I have recently bled the system properly twice and also replaced the brake hoses, with another proper bleed. The accumulator is about 12 months old.
I'm wondering if this is something to do with the modulator.
I've read bits about the brake modulator, there is a fine mesh screen in there that gets clogged, others have put some type of kit through and cleaned the whole modulator out as well.
I have not tackled the modulator before, so if anyone can share their experiences with this I'd be most appreciative...or any other suggestions you may have!
Cheers, Pete.

[TheTree]

Pete

I am not sure about the whooshing sound but the brake modulator thread is here

http://www.aulro.com/afvb/p38a-range-rover/53794-all-p38-owners-up-mid-1999-please-read.html

Perhaps another bleed might solve the problem?

Steve

[PeterH]

Thanks Steve, I've been doing a bit of research on this and I think you may be right, could just be air in the system still.
I'll fit that other short brake hose and give it another full bleed...fingers crossed!
Other than that, the brakes are working perfectly, pump is running as it should, no fluid leaks, new fluid right through.
Mine is a 2001 P38, which should not have the plastic components described in that thread.
Interesting read though, seems like a major oversight on Land Rovers part, it was probably cheaper to put plastic components in rather than metal.

[Hoges]

Hi Pete,
I suspect that LR simply bought the complete assembly from Wabco...and that warranty claims from LR forced a change to the Wabco production line... full marks to Russell Botha for his persistence in developing a local "fix" for parts which are otherwise "unobtainable" ...and he provides a CD with detailed instructions!!

[mtb_gary]

I've installed one of Russell's kits. Not a hard job, and well worth the effort! Bleeding the brakes as per RAVE with SWMBO remains the hardest part ;)

Gary

[PeterH]

I was wondering if I need to give my modulator a clean out. In particular the fine screen inside the reservoir can get clogged, thought that may be playing funny buggers with my pedal. Of course pulling the modulator apart would probably require new seals etc which are probably in that kit. I'll give the system another bleed and see where it's at.
Thanks for the replies, Pete.

[mtb_gary]

Peter, if you are going to bleed the system again consider removing the reservoir and cleaning the filter on the bottom of it. The reservoir simply pushes into rubber seal on top of the modulator and is not pressurised. It can be prised out fairly easily with a couple of screw drivers.

Gary

[PeterH]

Gary, you are a champ! That is exactly the info I needed.
I want to clean that screen, but didn't know how to get to it.
Just to be clear, the reservoir just levers off the top of the modulator?
It is my understanding that screen is inside the reservoir, once it is off, how do I get to the screen?
Never done this before, just want to be prepared.
Thanks, Pete.

[Hoges]

just make sure that you wear protective gloves...those blue nitrile gloves from Coles/Woolies are ideal. The glycols etc in brake fluid are on the nasty list and you don't want to be absorbing it through your skin...

[PeterH]

Thanks Hoges, I'm a painter and decorator by trade, so I have a good supply of those extra strong black nitrile gloves, always have a pair on when working on the car.
Aside from the protection from nasties, it's great pulling the gloves off at the end of the job to find clean hands underneath!

[mtb_gary]

Peter, to firstly drain the reservoir I found thet disconnecting the low pressure hose on the pump end rather than the reservoir end gave me an easier way to drain the reservoir into a small measuring jug. When the jug starts to fill up put your thumb on the end of the hose to stem the flow of brake fluid whist you then empty the collected brake fluid into a larger container. ( I hopee that makes sense). Once the brake fluid is drained from the reservoir you can then gently lever it out of the modulator (it is a press fit into a rubber seal). The filter is part of the reservoir and cannot be removed for cleaning, but soaking the reservoir in a dish of warm soapy water will clean it up pretty well. Then rinse thoroughly and dry. I let mine dry in the sun for a day making sure it was free of any moisture.

Gary

[PeterH]

Nice one Gary, will give that a go.
Thanks for the great tips, will let you know how it goes.
Cheers, Pete.

[benji]

Peter my brakes do the same thing, a slight wooshing noise, and the faster I press the brake pedal the more noticable it is.
My 93rrc did the same thing so I assumed it was normal. Both cars will pull up amazingly quick.

Sent from my GT-I9305T using AULRO mobile app

[PeterH]

Thanks Benji, yes that is exactly what mine does, otherwise the brakes a great.
I'd love to know what causes it, could be as simple as a few stray air bubbles in the system.
Mine is definitely doing it less after being bled, I'm hoping it's just another bleed.
Will let you know how it goes!
Thanks,
Pete.

[glenhendry]

I am the same I have the woosh sound. Also, I changed my modulator (with a non-new replacement) and it is still there. I figured that it was supposed to be like that.

[mtb_gary]

Peter, I don't think cleaning the reservoir and filter will cure the whooshing sound but it will help your pump by not having to work as hard to pull the fluid through and of course less chance of contaminants in the system. My theory (and it is only a theory) is that the whooshing sound you are hearing is the rubber gaiter on the modulator. The linkage from the brake pedal to the modulator has a rubber gaiter on it and it may be that the shaft is sliding in and out of the gaiter producing a whooshing like sound......just a thought

Gary

[PeterH]

Thanks Gary, after having a close look at the braking system, I tend to agree with you, cleaning the modulator will probably not have any effect on the sound.
I had the same thought, as the pedal is connected to the modulator, I was suspecting something along those lines.
The brakes are working fine, so it's not really a safety issue, but it was getting a bit annoying having that sound every time I used the brake pedal.
Thanks for your thoughts on this.
Pete.