No Brake Pressure

[Sparky Marky]

Hi,

I Have A Problem With My Brakes And I'm Not Sure What To Try To Fix It. When The Engine Is Not Running The Brake Pedal Seems To Work And You Can Feel The Pressure Keeping It Up. When You Start The Car And Press The Pedal, It Goes All The Way Down Even When You Pump It. I Know There Is An Air Leak Somewhere As It Is Affecting The Turbo As When Engine Started It Sits At -4, When Flooring It The Needle Goes Upto Half Way Between The 0 And +6 And Drops Instantly You Take Your Foot Off The Accelerator Back To -4.

Would The Problem Be The Inlet Manifold Gasket As I Fould One Sitting In The Boot? As The Last Owner Changed The Head Gasket It Could Be Possible That They Didn't Change This, Or Is It Going To Be The Servo? The Master Cylinder Looks New Too.

Either Way Are They Going To Be An Easyish Job Or A Day Or Two?

Thanks In Advance

[Karma Supra]

If the brake pedal is going straight to the floor there must be a leak, a huge airlock (no fluid?) or a dodgey master cylinder.... the fact that it only goes down when the brakes are assisted suggests that its probably the master cylinder, Are you losing any fluid?? When was it last changed?

As for the boost guage, its meant to be on negative at idle, that is the engines natural vacume although your boost does sound rather low...

[Sparky Marky]

I Bled The Brakes The Other Day To Make Sure There Was No Air Locks. The Fluid Looks Very Clean And The Master Cylinder Is Still All Shiny. I Thougt It Might Be The Inlet Manifold As Got Lots Of Spare Parts From A Headset. I Hope It Is As Simple As The Master As My Biggest Fear Is The Servo Being Faulty. There Is No Sound Of A Big Air Leak. As The Head Gasket Has Been Changed I Thought That Maybe If The Inlet Manifold Had Been Disturbed On Removal Of The Head.

There Is A Small Air Whistle Coming From A Component Near The Inlet Manifold. It Has A Large Pipe At The Bottom Of It And 2 Vacuum Pipes Either Side Of it. It Is Like A Filter As The Top Comes Off and There Is A Filter In It. It's About 3" In Dia And About 4" In Depth, It Is Held Into Place By A Clip.

Oh, I'm Not losing Any Fluid From The Brakes.

[vitaly]

I Bled The Brakes The Other Day To Make Sure There Was No Air Locks. The Fluid Looks Very Clean And The Master Cylinder Is Still All Shiny. I Thougt It Might Be The Inlet Manifold As Got Lots Of Spare Parts From A Headset. I Hope It Is As Simple As The Master As My Biggest Fear Is The Servo Being Faulty. There Is No Sound Of A Big Air Leak. As The Head Gasket Has Been Changed I Thought That Maybe If The Inlet Manifold Had Been Disturbed On Removal Of The Head.

There Is A Small Air Whistle Coming From A Component Near The Inlet Manifold. It Has A Large Pipe At The Bottom Of It And 2 Vacuum Pipes Either Side Of it. It Is Like A Filter As The Top Comes Off and There Is A Filter In It. It's About 3" In Dia And About 4" In Depth, It Is Held Into Place By A Clip.

Oh, I'm Not losing Any Fluid From The Brakes.

Did you resolve your issue with bad brake pressure?

I am having same issue with my Toyota Sienna.

I have a 2004 Toyota Sienna.

The brake pressure is bad.

I have to press the brake pedal 3 times to have brake pressure to stop.

I have replaced the master cylynder and the booster.

Also, have took it to the dealer to properly bleed the brakes.

Still no pressure...

Has anyone had this issue, and if so then how did you resolve this issue.

Thank you

[Leeky]

I had exactly the same issue on my mk2 supra. Its going to be the servo. Get yourself a new brake servo and that will sort it out.

While you are at it, change the master cylinder too if it looks like fluid has been rusting the servo just below where the master bolts on.