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Re: Brake bleeding, rear wheels

On Sat, 4 Jan 1997, Meron wrote:

> subject car is 86 5Kcstq wit ABS

I just did this same car (my own '86 5KCSTQ) Thursday night with no
problems, although I used Brendan Rudack on the brake pedal, and did it
manually.  "down - open, shut - up, down - open, shut - up, down - etc..."

> -I rigged a pressure cap to allow compressed air into the MCylinder and
> used 10-25 PSI for pressure 

Wow, I had the cap popping off with less than 10psi when I tried this on 
my neighbour's 5KCSTQ!  I ended up using about 3-5 psi max.

> -the strainer is removed from the MC
> -the MC is full of pentosin

Is this a typo, or are you serious here?  If you are serious, then either 
you are using Pentosin in the brake system which is a no-no - you should 
be using a good brake fluid, not "Pentosin."  The other mistake that 
strikes me as possible, given this typo, is that you are pressurizing the 
Pentosin reservoir, which is for the hydraulic assist of the brakes and 
steering, and has nothing to do with bleeding the brakes' hydraulic system.

> -the ABS is turned off with the ignition off
> -the ABS is turned off with the ignition on
> -the ABS is turned of with the car running
> -the ABS is not turned off, car not running

ABS on or off doesn't matter I don't think, does it?

> -brake pedal pushed in (mechanically, via a bar between the seat and the
> pedal)

Ah hah!  If the pedal is pushed in, you have closed off the passage that 
goes from the reservoir to the master cylinder.  The pedal must be up all 
the way for brake fluid to travel from the reservoir to the master cylinder.

> -bled the  MC, plenty of pentosin from both lines
> -bled the brake lines after the ABS hyd. unit, steady run of fluid but not
> a gayser!
> -moved the lever of the brake proportioning valve lever, no difference
> -bled the brake proportioning valve, very little pentosin
> -looked for a hight sensitive proportioning valve, did not find any

The height sensitive brake pressure regulator is the one on the left rear 
trapezoidal arm that has the lever on it.  Since this is the only one 
with a lever on it, you obviously moved it, but didn't realise exactly 
what it was.

> -looked in the Bentley for brake bleeding procedure, NOTHING Helpful
> (looked in two books 85-89 and 89-92 no help
> NO PENTOSIN at the rear with all the above steps!!!!!!!!!!!!!!!!!!!
> front bleed OK (with car off and  ABS is normal position)

I'm not sure why you were able to bleed the front.  Maybe Achille (who 
recently dismantled an MC) might have a clue as to why you got fluid at 
the front at all.

BTW, I just put in Stainless steel brake lines, and I bled the brakes 
with the new Performance friction brake fluid which has a (claimed) 
boiling point of 550 deg F.  I now have a very hard brake pedal.  As 
Brendan says, "Its welded to the firewall!"  I had no clue what he meant 
when he said this!  :-)


Later, ---------------------------------------------------------- 
Graydon D. Stuckey 	'85 Mazda RX7 GS, no toys 
graydon@apollo.gmi.edu 	'86 Audi 5000 CS Turbo Quattro, has toys
Flint, Michigan USA	'89 Thunderbird SC, lotsa toys