Identify brake symptom
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- slowcoach
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Identify brake symptom
Hi all,
My brake pedal feels firm and 'bites' at the usual point (quite high up). Brakes effective as always have been. No fluid has been lost, as the level is good. But..
When I hold pressure on the pedal, it gradually sinks to the floor. If I pump the pedal , it returns to being firm. I've not had any brake work done for a while, so shouldn't be any air introduced. The whole brake fluid was changed about a year and a half ago.
I Seem to remember this is a pointer to something failing... Cylinder, servo? Or something else? Thanks !
My brake pedal feels firm and 'bites' at the usual point (quite high up). Brakes effective as always have been. No fluid has been lost, as the level is good. But..
When I hold pressure on the pedal, it gradually sinks to the floor. If I pump the pedal , it returns to being firm. I've not had any brake work done for a while, so shouldn't be any air introduced. The whole brake fluid was changed about a year and a half ago.
I Seem to remember this is a pointer to something failing... Cylinder, servo? Or something else? Thanks !
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1984 TRAKKA Conversion Subaru EJ20 5 Speed
1984 TRAKKA Conversion Subaru EJ20 5 Speed
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- Trader
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Re: Identify brake symptom
Leaking seal, most likely a rear wheel cylinder
- ZsZ
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Re: Identify brake symptom
If no slave cylinders leak then there is some minor rust pitting inside the master cyl.
Zoltan
1986 Multivan ex-Caravelle. Van since 2006, running mTDi 1Z since 2008 with Fiat Croma 1.9 TDid pump 2008-2019, custom pump since 2019
5spd custom box 4.57 diff + 0.74 5th
1986 Multivan ex-Caravelle. Van since 2006, running mTDi 1Z since 2008 with Fiat Croma 1.9 TDid pump 2008-2019, custom pump since 2019
5spd custom box 4.57 diff + 0.74 5th
- slowcoach
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Re: Identify brake symptom
I can look at the rear cylinders, but don't think there's any loss there (level hasn't dropped)
The master cylinder does look pretty old. Changing the master cylinder looks simple enough, and high up to avoid the need for much bleed problems.
Wouldn't be the brake servo then? Do they outright fail when the time comes?
The master cylinder does look pretty old. Changing the master cylinder looks simple enough, and high up to avoid the need for much bleed problems.
Wouldn't be the brake servo then? Do they outright fail when the time comes?
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1984 TRAKKA Conversion Subaru EJ20 5 Speed
1984 TRAKKA Conversion Subaru EJ20 5 Speed
- 937carrera
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Re: Identify brake symptom
Something at the back of my mind said likely brake servo fault. Check that there are no leaks from the hoses
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
- T25Convert
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Re: Identify brake symptom
Dropping pedal shows that the system can't maintain a pressure, so there is a leak somewhere.
If its not loosing fluid the leak must be internal - I think the only thing that fits the bill for this is the master cylinder where fluid could bleed back past the seals into the reservoir.
Servo you can test. Engine off, pump the brakes a few times (to deplete vacuum in the servo) which should give you a hard pedal. Keep the pedal pressed down and start the engine - as you start it the pedal should drop a little as the vacuum forms and the assistance from this kicks in.
If its not loosing fluid the leak must be internal - I think the only thing that fits the bill for this is the master cylinder where fluid could bleed back past the seals into the reservoir.
Servo you can test. Engine off, pump the brakes a few times (to deplete vacuum in the servo) which should give you a hard pedal. Keep the pedal pressed down and start the engine - as you start it the pedal should drop a little as the vacuum forms and the assistance from this kicks in.
RIP - George - 1.9DG '85 AutoSleeper Trident - rusted away
George Second - 1.9DG '89 Caravelle
George Second - 1.9DG '89 Caravelle
- slowcoach
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Re: Identify brake symptom
Thanks, I'll do the pedal test [THUMBS UP SIGN]
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1984 TRAKKA Conversion Subaru EJ20 5 Speed
1984 TRAKKA Conversion Subaru EJ20 5 Speed
- Mocki
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Re: Identify brake symptom
Master cylinder seals on the way out , happened to my early t4 exactly as you described
Steve
tel / txt O7947-137911
________________
1989 2.1LpgWBX HiTop Leisuredrive Camper
1988 2.1 Caravelle TS TinTop Camper
tel / txt O7947-137911
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1989 2.1LpgWBX HiTop Leisuredrive Camper
1988 2.1 Caravelle TS TinTop Camper
- itchyfeet
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Re: Identify brake symptom
Mocki wrote:Master cylinder seals on the way out , happened to my early t4 exactly as you described
this ^^^ had to do the pop top for the same fault.
often happens after changing brake lines if you bleed by pumping pedal. as the seals move past their normal travel and get damaged.
best use a pressure bledder
- slowcoach
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Re: Identify brake symptom
T25Convert wrote:Servo you can test. Engine off, pump the brakes a few times (to deplete vacuum in the servo) which should give you a hard pedal. Keep the pedal pressed down and start the engine - as you start it the pedal should drop a little as the vacuum forms and the assistance from this kicks in.
Did this last night, and the pedal does drop/soften when the engine fires up, as you describe. thanks for that info guess a new master cylinder is on the cards. my next brickwerks order continues to swell
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1984 TRAKKA Conversion Subaru EJ20 5 Speed
1984 TRAKKA Conversion Subaru EJ20 5 Speed
- slowcoach
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Re: Identify brake symptom
brickwerks are out of stock and im ina bit of fix (imminent holiday)-
eurocarparts have PAGID ones..
https://www.eurocarparts.com/ecp/c/Volk ... 9b4&000032
I know theyre good for brake parts, is this a decent make of cylinder? I don't want to fit junk
eurocarparts have PAGID ones..
https://www.eurocarparts.com/ecp/c/Volk ... 9b4&000032
I know theyre good for brake parts, is this a decent make of cylinder? I don't want to fit junk
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1984 TRAKKA Conversion Subaru EJ20 5 Speed
1984 TRAKKA Conversion Subaru EJ20 5 Speed
- 937carrera
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Re: Identify brake symptom
No specific experience, but Pagid usually tends to be decent stuff. However their clutch cables for Polos are utter cr*%
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
- itchyfeet
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Re: Identify brake symptom
slowcoach wrote:brickwerks are out of stock and im ina bit of fix (imminent holiday)-
eurocarparts have PAGID ones..
https://www.eurocarparts.com/ecp/c/Volk ... 9b4&000032
I know theyre good for brake parts, is this a decent make of cylinder? I don't want to fit junk
I fitted Pagid on mine works as it should
- slowcoach
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Re: Identify brake symptom
Thanks fellas
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1984 TRAKKA Conversion Subaru EJ20 5 Speed
1984 TRAKKA Conversion Subaru EJ20 5 Speed
- slowcoach
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Re: Identify brake symptom
urghh waste of time. went to collect the part from ecp, paid first at counter. the part appeared and looked like it had been kicking around the floor for years, box smashed up, cylinder was oxidised, and had no rubber bungs in. I explained I wasn't going to fit it and got a refund. no appologies, and "that'll take 2-3 business days" to refund back to me.
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1984 TRAKKA Conversion Subaru EJ20 5 Speed
1984 TRAKKA Conversion Subaru EJ20 5 Speed