Break Booster / vacuum Qs. - TriStateTuners.com :: Home of Tristate Auto Enthusiast

Proven · 03-01-2009, 02:00 AM

My main Qs. here is how can you tell if a break booster is going bad? Soft pedal I'm guessing? Any other signs? Reason I bring it up is because I'm getting a weird result with my break pedal. What happens is when I get into full boost and quickly go for the break the pedal has a much stronger feel to it. The pedal also feels like it is raised up more (compared to going for the pedal during normal driving).

Could this be poor vacuum?
Could it be a beat booster?
Could I be crazy?

Things to keep in mind are I did recently replace the main vacuum line going to the booster because the old one slit big time.

Could I have used to thin of a hose or to wide (interior of the hose)? It’s a solid hose so it shouldn’t be collapsing.

assault187 · 03-01-2009, 02:49 AM

Usaully when a brake booster is going bad or you have a lack of stored vaccum pressure the pedal is very hard to depress. For example the pedal feel is that of which when you pump the brakes with the car off, you can feel how stiff the pedal gets.

If you replaced the vacuum line to the brake booster, you make have forgotten the check valve that sits inline. Most cars lines to the brake booster have a one way check valve to prevent braking pressure from escaping when pressing the pedal or to prevent excess pressure in the booster (I dont remeber exactly but either way its a problem). Most OEM lines have an internal valve that isnt really noticable or seen untill you feel around a bit or try to blow through both sides. Check the OEM one if you still have it, It should have a flow arrow and you should only be able to blow threw it one way. If you no longer have the OEM line, Pick up a new OEM line or check valve

Proven · 03-01-2009, 03:54 AM

You could be right about a valve being within the hose because I didnt see any valve on the exterior thats for sure. Unless the valve is past the hose I replaced towards to engine itself and I never touched it.

I hate valves. Most likely if its anything its a friggin valve with me (have gone threw 4 bov's breaking/not working on me).

Anyone know if a mild boost leak (mild enough to were I can still drive the car fine without it stalling) would cause this? Odly enough my BOV flange welds have some holes developing.

By the way assualt still working on that AWD conversion?

assault187 · 03-01-2009, 01:07 PM

Nah, the conversion is all wrapped up and ready to bite the pavement, I just have to recieve my trans and drop the motor in.

03-01-2009, 02:00 AM	#1
Proven Tri-State Post Whore Join Date: Feb 2006 Member #1547 My Ride: 99 RS-WRX iTrader: (0)	Break Booster / vacuum Qs. My main Qs. here is how can you tell if a break booster is going bad? Soft pedal I'm guessing? Any other signs? Reason I bring it up is because I'm getting a weird result with my break pedal. What happens is when I get into full boost and quickly go for the break the pedal has a much stronger feel to it. The pedal also feels like it is raised up more (compared to going for the pedal during normal driving). Could this be poor vacuum? Could it be a beat booster? Could I be crazy? Things to keep in mind are I did recently replace the main vacuum line going to the booster because the old one slit big time. Could I have used to thin of a hose or to wide (interior of the hose)? It’s a solid hose so it shouldn’t be collapsing. __________________ If they don't make it... Build it!

03-01-2009, 02:49 AM	#2
assault187 Tri-State Post Whore Join Date: Jul 2006 Location: Montgomery county Member #2176 My Ride: 97 Mitsubishi Eclipse GST Spyder AWD iTrader: (3)	Usaully when a brake booster is going bad or you have a lack of stored vaccum pressure the pedal is very hard to depress. For example the pedal feel is that of which when you pump the brakes with the car off, you can feel how stiff the pedal gets. If you replaced the vacuum line to the brake booster, you make have forgotten the check valve that sits inline. Most cars lines to the brake booster have a one way check valve to prevent braking pressure from escaping when pressing the pedal or to prevent excess pressure in the booster (I dont remeber exactly but either way its a problem). Most OEM lines have an internal valve that isnt really noticable or seen untill you feel around a bit or try to blow through both sides. Check the OEM one if you still have it, It should have a flow arrow and you should only be able to blow threw it one way. If you no longer have the OEM line, Pick up a new OEM line or check valve __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. World record holder for Quickest and Fastest 1/4 mile Spyder, 4 cylinder vert, 1st in 10's, 2.0L 4G63 Holset record, Modified Mag December 2010, Self built, self tuned. Last edited by assault187; 03-01-2009 at 02:56 AM.

03-01-2009, 03:54 AM	#3
Proven Tri-State Post Whore Join Date: Feb 2006 Member #1547 My Ride: 99 RS-WRX iTrader: (0)	You could be right about a valve being within the hose because I didnt see any valve on the exterior thats for sure. Unless the valve is past the hose I replaced towards to engine itself and I never touched it. I hate valves. Most likely if its anything its a friggin valve with me (have gone threw 4 bov's breaking/not working on me). Anyone know if a mild boost leak (mild enough to were I can still drive the car fine without it stalling) would cause this? Odly enough my BOV flange welds have some holes developing. By the way assualt still working on that AWD conversion? __________________ If they don't make it... Build it!

03-01-2009, 01:07 PM	#4
assault187 Tri-State Post Whore Join Date: Jul 2006 Location: Montgomery county Member #2176 My Ride: 97 Mitsubishi Eclipse GST Spyder AWD iTrader: (3)	Nah, the conversion is all wrapped up and ready to bite the pavement, I just have to recieve my trans and drop the motor in. __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. World record holder for Quickest and Fastest 1/4 mile Spyder, 4 cylinder vert, 1st in 10's, 2.0L 4G63 Holset record, Modified Mag December 2010, Self built, self tuned.

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