Brake Booster Question

Reply Subscribe

Thread Tools

Search this Thread

Dec 23, 2012 | 06:28 PM

PStruwing

Thread Starter

Senior User

Joined: Dec 2007

Posts: 419

Likes: 2

From: Lakefield Ontario

Brake Booster Question

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w

oNotPromoteQF/> <w:LidThemeOther>EN-CA</w:LidThemeOther> <w:LidThemeAsian>X-NONE</w:LidThemeAsian> <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w

ontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w

ontVertAlignCellWithSp/> <w

ontBreakConstrainedForcedTables/> <w

ontVertAlignInTxbx/> <w:Word11KerningPairs/> <w:CachedColBalance/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument> </xml><![endif]--> First Merry Christmas to all!

Second, just a question. When I am driving and push the brakes it feels very soft. If I pump the brake pedal more than 3 times it gets super firm! This is repeatable.

I am assuming it is a vacuum leak or the booster going south.

Any other ideas?
<!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority

9; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} </style> <![endif]-->

Dec 23, 2012 | 08:06 PM

Club Wagon

Posting Guru

Joined: Feb 2007

Posts: 2,351

Likes: 8

Check vacuum brake booster after turning off motor. First it should hold some vacuum for several moments, you can test for it by pressing brake pedal & hearing hiss. Also even immediately upon shutting off motor it should require several strokes on brake pedal to bleed vacuum reserve. If vacuum is lost in seconds, or within a stroke or 2 on pedal it's probably leaking.

Once vacuum reserve is depleted press pedal down & hold down, then start motor. You should feel a good vacuum booster bear down on master cylinder hydraulic pressure thru brake pedal.

The symptom "If I pump the brake pedal more than 3 times it gets super firm!" sounds more like air in system and/or messed up automatic rear brake adjusters.

Dec 23, 2012 | 10:16 PM

joshofalltrades

Postmaster

Joined: Feb 2011

Posts: 3,560

Likes: 1

yeah, that sounds more like either loose rear brakes or air in the line somewhere. check for leaks at all 4 brakes, and check the reservoir to see if its gone down any. often leaking fluid out also allows air to suck in and can really screw with you like that

since you have a gas engine, the supply of vacuum is enough that it'll have way more suction at idle than you can possibly consume with your booster