Brake pump failure symptoms

[A80Avant]

Hi

can anyone tell me what would the brake pump failure symptoms would be? ... Other than a head on collision due to brake failure!!

Since i replaced the brake bomb twice with the help and top notch service from Paul(custom autocraft), the brakes have improved very much and the feel is much improved, as well as the number of pedals with engine off till you reach the rock pedal.

However, im still getting that spongy feeling on and off as well as there is still some play on the pedal itself.

Brake shoes/discs are recently changed, i have braided pipes all over, new hose going from the pump to the bomb recently done(was leaking power steering fluid). No leaks anywhere else, no reduction in brake or PS fluids.Brakes have been bled to death.

The pump itself has never been touched and it is one of the long ones that some rs2s came with. Unfortunatelly i cannot see the part number.

Anyone can tell what else to look for? Anyone can source a brake pump cheap?

What does the brake pump master cylinder do? could that be the fault?

thanks

[montez]

What brake fluid you got? When was it last replaced?

I am using this ATE Super Blue Racing Brake Fluid and after a full bleed it improved my brakes a lot.

[Rusty]

Castrol Super DOT 4 (comparable to super blue) and Goodridge hoses made a big difference! I think the pedal on these cars is just a bit spongy, my BM has a vac servo and the brakes are much more positive, despite a rather tortuous linkage to the passenger side!

If you're running DS2500 then they will feel wooden till you get some heat in them, get them smoking and the brakes will be much better for a few weeks.

Other than that, the brake servo could be at fault, as could the M/C itself.

[A80Avant]

thanks for the responces. I use Motul DOT 5 as i always did. And also the high pressure hose from the PAS pump to bomb was also replaced about 5K ago, which was leaking.

[A80Avant]

i use textar pads as well, as always. Pedal definitelly seems different than before which again had the same excact stuff on.

things that havent been done are brake calipers refurb and obviously the pump and M/C. Obviously the master cylinder is cheaper to change and replace, you think that would be the first to go?

[montez]

How long have you been using dot 5 for? It is notorious at mixing badly with any small bits of dot 4 making a horrible sludge, esp in and around the seals etc, had it on a previous car and found it difficult to bleed as it holds air easier

[A80Avant]

as far as i can remember this car has only used dot5 and never anything different. the only thing was that originally the dot 5.1 from motul was recently changed to dot 5, but they told me it is the same thing.

[montez]

I did not think dot 5 and dot 5.1 were compatible. Dot 5.1 is similar to dot 4 racing and is a polyethylene glycol compound, where as dot 5 is silicon based. When the two mix they react and go all sludgy if you are going to change between the two you need to do a full system flush.

[A80Avant]

i see.Damn motul dealer!!!

well, how do you do that then? And also after a complete flush, which is best stuff to use?

[montez]

That is about as far as my knowledge on brake fluid goes, I know you have to use special flush so not to damage your brake lines. As far as what to use in the future it depends on how you use the car and personal preference, if it is for track and constant hard use you may benefit from dot 5, but it requires changing more often and can be more aggressive on the seals. Dot 4 is ample for most day to day use, and dot 4 racing/dot 5.1 for somewhere in between. I am sure someone else will be able to give you some more information.

[A80Avant]

thanks for that! will arrange for a flush soon

[Error404]

DON'T use DOT5 it will destroy the seals in your system. You need mineral based fluid not synthetic silicon based DOT5.
Use DOT 4 or 5.1 - generally DOT5.1 has a higher boiling point but it depends on the fluid

[A80Avant]

a wonderfull... another clue!

now i can only hope i havent @$%#& up already..

[A80Avant]

final question,

i have already booked the car in when i return to have the whole system flushed and brake fluid replaced.

I see from the opie oils website that there is only about 25C difference between the DOT 5.1 and DOT 4 that motul has as far as boiling point.

For a car that practically doesnt go into a track, and is being used everyday, would a DOT4 be enough?