E21 320i booster acting strange

[KU Roo]

So I've had my S52 swap running for a few months and I'm loving the power. One issue, the brake pedal does not seem like it should. I used the e21 booster and stock MC for my swap.

The pedal requires more effort then I have ever expereinced with the old e30 booster. I've read that since the e21 booster is smaller, you get less assist but here is what makes me think there might be a problem - when I turn the car off with my foot on the brake, the pedal "pushes" back on my foot.

I cannot remeber which vacuum hose I used, the e30 or e21 one. I seem to recall reading on another post that there might be a valve on the e21 hose that keeps vacuum held in the booster. Is this correct? Could I be missing this valve? Where does it go exactly?

Thanks for any help you can give.
Roo
'90 325i S52

[Massive Lee]

Did you fit the rubber seal between the MC and the booster?

[KU Roo]

Yup, black O-Ring was there on the MC.

[M-technik-3]

There is a check valve is that on the intake?

[KU Roo]

There is no valve on the intake side that I can see, just a plastic niple where the vacuum hose attaches.

Do you mean the non-return valve on the booster side of the hose items #7 or #8 in this?
http://www.realoem.com/bmw/showparts...63&hg=34&fg=25

I am wondering -if the valve on the booster side of the vacuum hose is shot, then could that be my problem? Or should I try and check for vacuum leaks at the base of the MC where is meets the booster in case the o-ring got messed up during MC install?

Thanks for your input.

[M-technik-3]

I had mine on mounted on the intake side ala a e34 style. The valve could be bad things do fail.