TheSamba.com Forums
 
  View original topic: Brake pump troubles
Komissar Fri Aug 08, 2014 11:20 am

Hello,

I have just beet through a frustrating experience with my brake pump (master cylinder) and wanted to share it with others. Maybe looking for advices as well, even though at this stage the things are (sort of ) clear to me.

Long story short - 6 years ago after I have bought my 1965 Beetle I have replaced every single component of my braking system. At that time i have up-graded to dual circuit as well, with a LPR brand pump ( lpr website: http://www.lpr.it/index.php?&lang=en ) - the pump was purchased through the local parts store and it was advertised as a "VW 1200 1969- 1984 main brake pump).

Since then I have used my beetle constantly as a daily driver, with excellent use of my brakes. Basically I have never touched the system since then, except for the occasional shoes adjustments and a front brake pads replace (FERODO brand) and maybe 3 years ago when I have changed the brake fluid suspecting an air leak (which turned out to be a false alarm) .


In the last year I have started to notice a slight decrease of braking performance, which appeared (to me at least to be much more significant in the front brakes) . Believing that is just a case of worn-out shoes and old brake fluid, this week I have decided to replace the front shoes and the fluid.
I have started replacing the shoes (which truth be told did not look that bad) and then I have replaced the fluid. I have started bleeding wheel by wheel starting wit the most distant one from the master cylinder. A friend was pumping the brake while I was opening the bleeders and watched how the old fluid draine through a hose in a glass container.

(all the brake shoes were correctly adjusted - and the pedal push rod adjusted corretly to 1-2 mm of freeplay).

After that I have noticed that my brake pedal was ineffective. One could easily push the pedal right through the firewall and no braking took place.

I have said to myself, "ok, i got air bubbles" and proceeded to rebleed the system by pumping the brake method. I have done it by the book a lot of times and still absolutely no improvement.
However, while pumping, fluid was coming out through ALL of the bleeding nipples respectively.

The best case scenario was the situation when the pedal fully pressed engaged rather poorly the brakes at the point when the pedal touched the firewall.

The second day I have tried to bleed them with a power bleeder system. Still no succes and no improvement what so ever.

At this point I have decided that my brake master might be bad. So I have removed the gastank and removed the "old" (6 year old ) unit.

Already I have ordered a new one but I have to wait for it until monday or tuesday. I have opened the old one to look at its rubber seals but they seemed OK-ish to me.

I hope the new master will solve my problem. - i have already checked all my hard and flexible lines with compressed air and all of them are clear - no obstruction whatsoever.


Did anybody experience anything similar ?

VOLKSWAGNUT Fri Aug 08, 2014 12:08 pm

It sounds like a worn master... to me as well.
but ... I've had 2 puzzling issues with brake fluid here lately..

Hence one brake fluid worked fine.. while another didnt work at all..

I know sounds nuts... :wink:.. but this is what happened.

Full change out of master cylinder , properly bench bled and the whole jazz..
Couldnt get a pedal after installation (and had one before removal).
When I ran out of the first Dot 3 brand, picked up a second brand.. and tah dah.. problem was solved.. :-s

Now these both started as sealed bottles...

I tested the "feel", "smell", "look" of both fluids .... it was night and day difference.

The first spec'd for American cars was like typical brake fluid which IMO has a less slick sort of hot feeling and smelled like Dot 3 or 4 brake fluid, a sort of sweet smell. Transparent clear to tan color
The second one spec'd for Asian cars was slick more like oil and smelled sour... like bad chinese.. :lol: (Thats just a joke...) Clouded transparent, light puke green color..

Not sure of the whole chemical compound.... they were both Dot 3 and were totally different.

I will say.. its my first experience with the Asian spec fluid.. maybe it has more corrosion inhibitors.. :-s

It seemd to build a better pedal..


.

Not all Dot 3 or 4 are created equal..

I had a similar issue when I topped off a modern hydraulic clutch master.. GM spec DOT 3 fluids... one built pressure the other didnt do shit..
I even tried GM spec clutch fluid... Only one brake fluid built pressure..


./

drscope Fri Aug 08, 2014 2:53 pm

About the only brake fluid we have around here for the road cars is Castrol LMA. And that is because we had a few British cars in our stable and that is all you could use in them. If you used something else it would effect the rubbers since British cars used natural rubber or something.

So since the Castrol LMA could be used in anything, but HAD to be used in the old British cars, we decided not to have anything but LMA around.

Dual Circuit masters like to have the fronts bled first. Not sure why, but thats just what works best. It may also help to adjust the shoes out until the drum either will not turn or is very difficult to turn.

VOLKSWAGNUT Sat Aug 09, 2014 5:04 am

Ill have to pick up some Castrol LMA (if I can find it) to compare to the Asian spec fluid.. maybe thats the difference.

.

Komissar Thu Aug 14, 2014 3:58 am

A short and frustrating update :)

My new master has arrived on Monday - i have tried to install and bleed it to no avail. For two days I have tried in vain to bleed it, either by pumping the pedal or by powerbleeding it.

In the end, the best scenario we managed to come to was the rear brakes engaging at the end of the pedal play, when the pedal almost touched the front firewall.

We jacked up the car and tested the actual braking - with the pedal up to the floor, the rear wheels were locked but the front ones were spinning almost trouble free ( the shoes were adjusted tight from those star adjusters).

Could there be e problem with the front cylinders ? I have just ordered a pair just to be sure.
All the brake lines (metal and rubber) were replaced about 5 years ago with new stuff - as well as the cylinders - and I have never seen a leak and never lost fluid from the reservoir, but who knows.

Cusser Thu Aug 14, 2014 5:42 am

Did you bench bleed the new master cylinder, so it would suck up new brake fluid on the return stroke, and not suck in air?

Bring the VW to me, in Phoenix, AZ, USA and I'll fix it. Belgium can't be too far....

Komissar Thu Aug 14, 2014 6:04 am

Cusser wrote:

Bring the VW to me, in Phoenix, AZ, USA and I'll fix it. Belgium can't be too far....


It's Belgium+ 2100 kms :) - the car is in my home country, Romania. I've been to Belgium with it, though :)


I have "bench bled" the master in the car, so to speak. Hooked it up at the fluid reservoir and pumped it until fluid came out of all the orifices (both for the front and rear circuits).



Powered by phpBB © 2001, 2005 phpBB Group