Vacuum source for Brake Booster

[Pete_89T2]

Were the brakes working fine before the booster hose was changed? If so, another possibility is that the check valve was reinstalled backwards, which would prevent the booster from holding a vacuum.

[RETed]

I believe the largest fitting of the fittings inline on the back side (facing the firewall) of the upper intake manifold is for the oil injectors?
If so, this fitting is sourced BEFORE the throttle body, which means it will NEVER see vacuum.
This explains why your brakes are not working properly.

The brake booster needs to source vacuum AFTER the throttle body.
I believe this fitting to be at least 10mm?


-Ted

[RETed]

I just checked my Zenki FC turbo...
The brake booster fitting is on the surge tank of the upper intake manifold.
It's offset towards the passenger side of the car facing the firewall.
This is for US-spec engines.
It's basically the lowest fitting back there.

For J-spec upper intake manifolds, there's a short banjo to pipe fitting that comes off the lower intake manifold right over the turbo.
This is to compensate for the RHD design which locates the brake booster on the opposite side of the firewall.


-Ted