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01 C2 possible Brake Booster failure?

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6 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis

THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCH01 C2 possible Brake Booster failure?

Reported or suspected cause

torn booster diaphragm or leaking seal

Suggestion or failed attempt

No successful repair reported for this finding.

0
Identified cause: 1
Suspected cause: 0
Reported fixes

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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.

Discussions that suspect a cause: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suspected cause
hissing when applying the brakes is more than likely a torn booster diaphragm or leaking seal.
Original post Read captured discussion
01 C2 possible Brake Booster failure?

Frequently discussed work

Smoke-test vac line

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Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion
U can smoke test the vac line and that would show if u have a leak to atmosphere.
Original post Read captured discussion
01 C2 possible Brake Booster failure?

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Leading evidence: 'torn booster diaphragm or leaking seal' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'torn booster diaphragm or leaking seal' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Smoke-test vac line' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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1 matching discussions · 6 captured posts examined · 0 partial discussions

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Smoke-test vac line

Suggestion or failed attempt

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion
U can smoke test the vac line and that would show if u have a leak to atmosphere.
Original post Read captured discussion
01 C2 possible Brake Booster failure?

Frequently discussed actions (1)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Smoke-test vac line

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion
U can smoke test the vac line and that would show if u have a leak to atmosphere.
Original post Read captured discussion
01 C2 possible Brake Booster failure?

Reported and suspected causes (1)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

torn booster diaphragm or leaking seal

No successful repair reported for this finding.

0
Identified cause: 1
Suspected cause: 0
Reported fixes

Read evidence and context

Discussions that suspect a cause: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suspected cause
hissing when applying the brakes is more than likely a torn booster diaphragm or leaking seal.
Original post Read captured discussion
01 C2 possible Brake Booster failure?

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Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.

6 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

Rennlist: 1 discussions

0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.

0 acknowledgements have no verified action link; they do not establish a repair result.

Generation: 20261027T140027Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Greetings, I've been experiencing spongy brakes with off and on hissing sound on my brakes. Recent research has me thinking of a brake booster failure and or a hose vaccuum leak. Im asking experienced gents here if I should start looking for a new replacement and If I should order vaccum hoses ? is the master cylinder a factor here. Thank you in advance.

POST 2Original post

Maybe pull a vacuum hose off the booster and see if there is fluid inside. The rear seal in the MC might have failed and be leaking into the booster. Could be spongy from leak and hissing from air into fluid. The fluid is often hard on the booster diagram if this is the case, so its days may be numbered if that is what you find.

POST 3 / ORIGINAL POSTEROriginal post

from what you're saying is its more of a master cylinder issue than the brake booster itself? thank you will try that.

POST 4Original post

U can smoke test the vac line and that would show if u have a leak to atmosphere.

POST 5Original post

Quotes source post: 20631351

hissing when applying the brakes is more than likely a torn booster diaphragm or leaking seal. You can try to pump brake pedal with engine off a few times till pedal gets hard, keep pressure on pedal and start engine. With a good booster pedal goes down a little and gets softer when engine is started and with no hiss. If pedal stays up & hard or you hear the hiss, booster bad. If you watch fuel trims when it starts to hiss you can see the trims change up from the vac leak... A leaking booster vacuum line would leak/hiss all the time not just when applying brakes.

POST 6 / ORIGINAL POSTEROriginal post

makes sense... thanks will do that! thanks

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