Na Brake Booster Can't Handle The Boooost

[R33 Jared]

I have an R33 GTS-t Series 1. It originally had an aspirated RB25 swapped into it for P Plater laws, 2 years into owning it I then reimplanted a S2 RB25det. All is sweet, only when I disconnect the brake booster to intake manifold hose. If that is connected, it makes a screaming sound, as if the brake booster could only handle atmospheric pressure, not the pressure of a turbo. What are my solutions here so i can still have safe, working brakes and the full 7pounds of boost?

[Ben C34]

One way valve

[GTSBoy]

Even though what Ben said is correct, I have no idea what the OP is supposed to mean.

Where is the screaming noise coming from? The booster? Or the end of the hose (the massive vacuum leak you created when you pulled the hose off)?

[Scott Black]

basically all working properly the booster should never see boost as stated above there is ment to be a one way valve in the line, if the booster actually sees boost the brakes wont work well at all. check the one way valve to ensure it works, and also make sure the booster isnt stuffed and leaking,
as above where is the screaming noise actually comming from and when does it do it, idle, driving, only on boost ?

[R33 Jared]

basically all working properly the booster should never see boost as stated above there is ment to be a one way valve in the line, if the booster actually sees boost the brakes wont work well at all. check the one way valve to ensure it works, and also make sure the booster isnt stuffed and leaking,

as above where is the screaming noise actually comming from and when does it do it, idle, driving, only on boost ?

I have bolted off the hoses so there is no leak. There is no valve what so ever between manifold and brake booster inlet. Will go search around for one, thanks guys.

[jiffo]

No need for an extra valve, the vacuum hose connection at the booster has the non return valve incorporated.

Are you sure the booster was OK prior to the transplant?

[Scott Black]

No need for an extra valve, the vacuum hose connection at the booster has the non return valve incorporated.

Are you sure the booster was OK prior to the transplant?

not really and easy enough to loose when people swap engines around, unlike alot of other cars the one way valve isnt actually the connection on the booster, yet a little upstream, heres a pic i stole from another sau thread to show it

its the little valve just behind the cap for the master,

however pushing boost into the booster may have damaged it to yet you will find that out when you fit a one way valve

[89CAL]

Thats an R32, I believe the check valve may be part of the connection to the booster in an R33 but may be mistaken

[jiffo]

You're correct, 32 GTR and that's an external check valve plus there's another for the clutch.

Haven't seen a booster with an external valve since the olden days.

Caught again!!!

[R33 Jared]

No need for an extra valve, the vacuum hose connection at the booster has the non return valve incorporated.

Are you sure the booster was OK prior to the transplant?

A few years back when I was a red P Plater I switched all the hoses to blue silicon ones. I had almost switched all the silicon hoses back to the genuine black ones except the hose from the brake booster to the intake. I went out into my parts bin, found the original hose (noticed it has a built in valve that the aftermarket ones didn't) and now it's working perfectly. Full boost and brakes! Thanks for the help though, would've had no clue otherwise. Summary is NA pressure doesnt require the valve, turbo does.

[Ben C34]

The valve should still be there for a na. Otherwise you instantly loose power brakes when the engine is off.

[GTSBoy]

Summary is NA pressure doesnt require the valve, turbo does.

Not true. The check valve IS required on NA in order to KEEP the vacuum inside the booster, so you don't have no assistance after WOT.

[jiffo]

Ben and GTSBoy are dead right.

N/A or turbo makes no difference, you must have a non-return valve either built into the booster or in the vacuum supply line.

Photo shows what I thought your car had, valve built into the vacuum hose connection.