Urgent help please! Lost power to brakes!

Amjad

Active Member
Oct 26, 2010
92
0
Cardiff/Southampton Uni
I bled my MS, then the front brakes simultaneously, then rear simultaneously and then fronts again. I don't believe there is any problem with regards to bleeding now.

I didn't think a damaged MS would be possible either, the causes that were suggested to me by my local quik fit and another mechanic were:

-Sticky calipers (which is very unlikely as I'm using my original calipers that functioned perfectly before)

-Hoses which may have expanded and can't reshrink (I have today replaced both flexi hoses with the ones that came with the new calipers, same length, calipers re-bled etc)

-Sliders/Where the pads sit and move being corroded (new carrier was less corroded than the old ones so this is an unlikely cause, but regardless of this I have cleaned the new ones up)

-Master Cylinder (explained below)

With regards to MS, like I said I didn't think it was possible as I thought a damaged MS would only mean that the pedal would drop to the floor rather than resulting in sticking brakes. The brakes were actually smoking after a 10 minute drive with a few stops from 40mph-0. But after having let the car sit for a few hours and starting it up again, the brakes were not sticking until they had warmed up again.

I read this earlier which explained why it could be the MS, as my car is presenting with similar symptoms:

1. "Long term retention of the residual pressure is NOT normal. If the system would always hold the fluid in this condition, the pads and shoes would never withdraw from the rotors and drums. It would then not be necessary to ever adjust the shoes in drum brakes, because they would be self compensating for wear, similar to the clutch slave cylinder, always keeping the shoes in contact with the drum. When pads or shoes are always touching the rotor or drum the resulting friction will make heat, and brake fluid will stay warm or get hotter. Heating brake fluid will expand, which would in turn cause a bit more fluid to return past the valve washer, maintaining 8 psi residual pressure in the system and continuing friction heating of the brake parts. When the vehicle stops and remains still for a while the brake parts and fluid can cool down, the fluid will contract, and any residual pressure in the system will vanish. This is why if you let it set for half an hour the wheel will turn freely." Taken from http://mgaguru.com/mgtech/brakes/bt101a.htm

2. "And this is where the foot pedal's "free play" comes from. It is absolutely necessary that there be some amount of clearance, otherwise the seals may be pushed forwards enough to prevent the intake/return ports from ever opening up again to allow excess pressure to vent to the reservoir. The factory manual for my car specifies 1mm to 5mm clearance. The intake/return ports are less than a millimeter in diameter, and the seal lips sit immediately behind them, so it doesn't take much of a misadjustment to close off the ports, even partially. Too little clearance here may cause the brakes to lock on slowly as you drive. Too much clearance will make your pedal feel soft, with excessive travel." Taken from http://www.tegger.com/hondafaq/mastercylinderreplace/howworks.html

So about my last post, can anyone help me with the following please:

Has anybody ordered a master cylinder off of one of the breakers on Ebay? There seems to be quite a few listed for around the £30 mark and I can't really afford a new one at this point in time (insurance and a recent major service have left the pockets quite empty!).

Lastly is there a guide on how to change the brake master cylinder? The engine bay is a lot more cramped than my other cars which I work on more frequently, don't wanna be struggling all day lol

Thanks guys

Amjad
 

Muttley

Catch that diesel!
Mar 17, 2006
4,987
29
North Kent
The Haynes manual covers master cylinder removal and replacement.

BLUE Book Haynes Number 4169 - 2001 - 2003 (X to 53 registration) 4-cyl Petrol & Diesel

Petrol

1.4 DOHC (55kW) - AHW, AXP, BCA

1.6 SOHC (74kW) - AEH, AKL

1.6 SOHC (75kW) - AVU, BFQ

1.6 DOHC (77kW) - AZD, BCB

1.8T DOHC (110kW) - AUM

1.8T DOHC (132kW) - AUQ

2.0 SOHC (85kW) - APK, AQY, AZU, AZJ

Diesel

1.9 (50kW) - AGP, AQM

1.9T (66kW) - AGR, ALH

1.9T (74kW) - ATD, AXR

1.9T (81kW) - AHF, ASV

1.9T (85kW) - AJM, AUY

1.9T (96kW) - ASZ

1.9T (110kW) - ARL

Does NOT cover 2.3 litre V5, or 2.8 or 3.2 litre V6 petrol engines.
Does NOT cover V5, 4-Motion, R32 or Cabriolet models, or new Golf range introduced January 2004
 
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