Power brake problem

[deemsriddle]

When I step on the brake pedal, it feels solid and unresponsive. I expect the brake booster may need rebuilding but I don't know the best route. Any help will be appreciated. Deems

[boyt911sc]

Check how much vacuum your brake booster is getting with the motor running. Without the correct vacuum, your braking power would feel hard and deficient. In the trunk, you will find the metal vacuum line and a rubber vacuum hose before the brake booster. Install a vacuum gauge in series and record your vacuum reading.

The brake booster could be leaking and requires some investigation. Keep us posted.

Tony

[Locker537]

In addition to Tony's check using a vacuum gauge, you can do a quick test without any additional tools.

With the car off, pump and hold the brake pedal. Start the car. The pedal should depress slightly as the booster builds vacuum and assists you.

[gomezoneill]

Originally Posted by boyt911sc

Check how much vacuum your brake booster is getting with the motor running. Without the correct vacuum, your braking power would feel hard and deficient. In the trunk, you will find the metal vacuum line and a rubber vacuum hose before the brake booster. Install a vacuum gauge in series and record your vacuum reading.

The brake booster could be leaking and requires some investigation. Keep us posted.

Tony

Thank's for not using the word FRUNK

[Pedro '84 Coupe]

Also check the vacuum line discussed here: https://forums.pelicanparts.com/porsche-911-technical-forum/435952-vacuum-leak-you-probably-didnt-ever-think.html

[john walker's workshop]

^^^^^^^^Just fixed one last week on a '77. Hard pedal and idle air screw bottomed out and still high idle is the giveaway.

[GH85Carrera]

There is one super easy place to check as well. I was working on my heater blower and somehow knocked this connection of on my 85 911.

It is just to the right of the cruise control module. With that off, the brake pedal was really hard to stop the car. The engine was running a bit strange, but the brake pedal was the instant clue of a vacuum leak.

[deemsriddle]

Well, this may answer another question, idle problems. Where does the vacuum line go?

[911obgyn]

The picture shows on the engine where the vacuum line for the booster goes, it is disconnected in the picture. The plastic venturi tube cracks also.

[Walter415]

Originally Posted by deemsriddle

When I step on the brake pedal, it feels solid and unresponsive. I expect the brake booster may need rebuilding but I don't know the best route. Any help will be appreciated. Deems

Your brake pedal is harder. A brake pedal should hit a sweet spot when you depress it — it shouldn't be too easy or too hard to push down. ...
Your brake pedal is higher. ...
Your stopping distance changes. ...
You hear a hissing sound. ...
Your car keeps stalling when you brake.

rapidfs