Brake booster leak? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

JerkFaceJason · 01-21-2003, 08:10 PM

I had been having idling problems, but I noticed that it only drops when I depress the brake. The idle will drop a few hundred rpms when the brake is depressed.

does the brake booster need to be replaced? and if it does, how hard is this on a scale of 1 to 10? 1 being changing your oil and 10 being... well.. really hard. thanks

*Jeff240sx* · 01-21-2003, 09:14 PM

Hmm. Is this an auto or manual tranny? Sounds like either a clutch problem, or clutch pack. The brake booster wouldn't cause your idle to drop. I've never heard of it.
-Jeff

kandyflip445 · 01-21-2003, 09:54 PM

It may be your booster. Or just a vacuum leak. Because, IIRC, when you press the brake a valve closes the diaphram(sp?) in the booster off leaving a vacuum on the engine side of the booster and exposing the other side to atmospheric pressure to give you that "boost". I may be wrong though....

But, just in case here is a test for the Vacuum Booster.
----------------------------------------------------------------------
Turn off the engine. Pump the brake pedal several times to eliminate any vacuum from the system. Depress the brake pedal with approximately 15lbs. of force. Start the engine. The pedal should move down. If it does not, check the vacuum supply to the booster.

If the pedal does move down, check the pedal feel. Allow the engine to idle for one minute, then shut the engine off. Apply the brake with the engine off. If the pedal is hard to push, check the vacuum systems and supply (especially the vacuum check valves). If pressing the brake pedal requires the same level of effort as it does with the engine running the power assist is all right.

Hope that helps!

Just PM me if you have any questions about this.

JerkFaceJason · 01-22-2003, 03:33 PM

thanks alot! I'll go try it right now and see what it does.

and yea, i'm fairly sure its a vaccum leak somewhere, and from the advice of a friend i figured it was probably a vaccum line somewhere near the brake booster

JerkFaceJason · 01-22-2003, 03:56 PM

yea, I checked all the the lines and they are ok, I'll have a guy i know look at it - thanks for the help

01-21-2003, 08:10 PM	#1
JerkFaceJason Leaky Injector Join Date: Jan 2003 Location: Texas Posts: 100 Trader Rating: (0) Feedback Score: 0 reviews	Brake booster leak? I had been having idling problems, but I noticed that it only drops when I depress the brake. The idle will drop a few hundred rpms when the brake is depressed. does the brake booster need to be replaced? and if it does, how hard is this on a scale of 1 to 10? 1 being changing your oil and 10 being... well.. really hard. thanks

01-21-2003, 09:14 PM	#2
Jeff240sx I hate you too... Join Date: Jul 2001 Location: Tampa, FL Age: 42 Posts: 5,828 Trader Rating: (0) Rides Gallery: Jeff240sx Feedback Score: 0 reviews	Hmm. Is this an auto or manual tranny? Sounds like either a clutch problem, or clutch pack. The brake booster wouldn't cause your idle to drop. I've never heard of it. -Jeff __________________ Whatup?

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01-21-2003, 09:54 PM	#3
kandyflip445 Post Whore! Join Date: Sep 2002 Location: Arden, NC Age: 40 Posts: 4,460 Trader Rating: (1) Rides Gallery: kandyflip445 Feedback Score: 1 reviews	It may be your booster. Or just a vacuum leak. Because, IIRC, when you press the brake a valve closes the diaphram(sp?) in the booster off leaving a vacuum on the engine side of the booster and exposing the other side to atmospheric pressure to give you that "boost". I may be wrong though.... But, just in case here is a test for the Vacuum Booster. ---------------------------------------------------------------------- Turn off the engine. Pump the brake pedal several times to eliminate any vacuum from the system. Depress the brake pedal with approximately 15lbs. of force. Start the engine. The pedal should move down. If it does not, check the vacuum supply to the booster. If the pedal does move down, check the pedal feel. Allow the engine to idle for one minute, then shut the engine off. Apply the brake with the engine off. If the pedal is hard to push, check the vacuum systems and supply (especially the vacuum check valves). If pressing the brake pedal requires the same level of effort as it does with the engine running the power assist is all right. Hope that helps! Just PM me if you have any questions about this.

01-22-2003, 03:33 PM	#4
JerkFaceJason Leaky Injector Join Date: Jan 2003 Location: Texas Posts: 100 Trader Rating: (0) Feedback Score: 0 reviews	thanks alot! I'll go try it right now and see what it does. and yea, i'm fairly sure its a vaccum leak somewhere, and from the advice of a friend i figured it was probably a vaccum line somewhere near the brake booster

01-22-2003, 03:56 PM	#5
JerkFaceJason Leaky Injector Join Date: Jan 2003 Location: Texas Posts: 100 Trader Rating: (0) Feedback Score: 0 reviews	yea, I checked all the the lines and they are ok, I'll have a guy i know look at it - thanks for the help