Brake booster question

[limey4657]

Just added a missing booster check valve on my 72 gt. (Finally figured out why it ran so poorly when I was slowing down for stop lights). However, before the install, when I cranked the engine, the brake pedal depressed a bit, indicating a properly functioning booster. Now that the check valve is installed with the arrows correctly pointed towards the intake manifold, the booster no longer pulls on the brake pedal when I crank the engine. When I pull the vacuum line off the booster I seem to be getting good vacuum when I place my finger over the open end. Any ideas about why the booster doesn't work with the new check valve? Limey 4657

[namba209]

I'm kinda guessing a bit here that you've got a real good booster and with the check valve installed it's holding a good vacuum. With the check valve out of the system, the vacuum bled off when you shut down the engine, then when you start the engine the vacuum builds up again, pulling the brake pedal. Next question, do the brakes feel harder to apply or are they the same?

[2 Fast 4 U]

Originally Posted by limey4657 ......Now that the check valve is installed with the arrows correctly pointed towards the intake manifold, the booster no longer pulls on the brake pedal when I crank the engine......

Is the check valve working good??, it seems before you installed the check valve all was OK

[limey4657]

Thanks for the input.

The addition of the check valve really didn't help with pedal pressure -which seems pretty stiff. I don't have much Opel experience, but it seems about what you would expect in brakes without power assist. With the check valve installed the stalling that occurred anytime I hit the brakes was fixed.

I removed the valve and blew through it to make sure it was unimpeded. It correctly allows easy airflow in only one direction.

The service manual indicates the way to check the function of the brake booster is to feel the brake pedal depress when you start the engine. That only seems to occur without the valve in place.

Know any other way to check the function of the booster?

Thanks again,

Art

[jlthunder]

Simple test. unhook the vacuum line from the brake booster and plug the rubber hose which goes to the carb. Drive your car and try the brakes.

Re hook up the vacuum line to the booster and drive the car. If you notice a difference(better braking with line attached), then your booster works OK.

The booster is not like on an American car where the difference is night and day. It is a little more like night and early morning.

[limey4657]

I've no headlights -so will try it this weekend. I'll look for a mild difference. Thanks.

[blancojp]

The other way to check it is when you press the brake pedal, the engine will go up in RPMs if the booster is bad. I replaced the Opel unit with a BMW E-30 booster which is a 9" unit. It bolts right in and you can reuse the master cylinder and reservoir. You will however need to create an "interface" to mate up with the brake rod but that is very easy to do.

[wrench459]

Originally Posted by jlthunder The booster is not like on an American car where the difference is night and day. It is a little more like night and early morning.

Agree its not a power booster at all more like power assist!