Brakes: Won't Bleed Properly

[opus10583]

Hi,

After installation of a new Master Cylinder my brakes won't bleed properly; high hard pedal with engine off, spongy and long with vacuum applied, and then as if the left front isn't working at all...

Previously, the brakes worked fine, with the MC slowly leaking at stop lights being the problem.

Any guesses? ...the locals are baffled and the latest self-proclaimed expert is a crook.

Thanks,
Mark
1978 CS1

[WYSpider]

Did you bleed the Master Cylinder first?

[124ADDHE]

to bleed the MC in-car, you need to jack the car through some extreme angles whilst bleeding thoroughly the calipers and tapping the MC with a ?something handy? , look at the line locations of the 3 (or2, depends how you look at it) circuits, apply logic, make sure and bleed both front calipers and at least one of the rears to expel the air from the MC. Bench bleeding saves many hours of PITA work.

Have fun!

PS some people may argue this one but when i rescently did my whole brake system overhaul I still found 1/2tsp of air in each front caliper, this is after extensive 2-man bleeding; I pulled them off whilst doing a follow-upgravity bleeding (the 2 person work was done, was just looking for a better pedal) and angled them slightly upwards to make the bleeder absolutely the highest point and tapping the caliper, i got this air and it was out of both calipers and an equal amount. to me this was very worthwhile I run boosterless to allow room for my dual carbs so you really can tell if there is any air!

[AndyS]

be sure to take into account the rear proportioning valve when bleeding 124 brakes. if the car is jacked up in the back and the axle is hanging down, it cuts off flow to the rears.

[WYSpider]

Opus, just so you are clear about what Andy is talking about.

For bleeding the rear brakes:
A. Disconnect one end of the connector pointed to by the red arrows.
B. Rotate the compensator rod (#5) up to its highest position.
C. Bleed the rear brakes with the rod up in the highest position.

Before the test drive be sure the connector in step A is reconnected.

[azruss]

i did a full system rebuild. I pre-filled the mc and all the calipers before i started bleeding. you can bleed your mc by cracking the fittings. it is a little messy.

[opus10583]

Thanks, all.

I didn't do anything: Shop A did the MC, and was fully aware of the Compensator issue. Couldn't get it.

Car has that vintage drum-brake feel, and a nasty slice.

Shop B gave me a wall-job and a bill for 1.5hr at $98 per.

They're going to get a chance to mend their ways...

I'll suggest they bleed the MC, and then the system, before they even think about charging me another cent.

Thanks,
Mark

[boogiedude]

If you had air in the master, the pedal would be spongy all the time. If it's rock hard with the car off, I doubt you have air in the system. And if the car is pulling one direction, you may need to grease the sliding blocks the caliper rides on and make sure it moves freely. Are the pads and rotors new? did you bed them in properly? being rude to the shop wont get you anything but a bad reputation

[opus10583]

Charging me $175 for a weeklong wall-job fairly well resets the rudeness bar.

[124ADDHE]

well is it fixed?

[manoa matt]

When I don't understand something, (wall-job) I look it up.

wall job definition

n.
a car—in the shop for repairs—which is parked against the wall with no repairs done. (The customer is charged anyway.) : [i]Places like those we surveyed may charge hundreds of dollars for what they call “wall jobs.”[/i]

[124ADDHE]

Well ,forgive me, maybe ill just go sit in a corner.

[manoa matt]

Keith, I didn't mean to offend you. I myself did not understand what he was referring to.

[124ADDHE]

Lol. All in good humour.

[whiterabbit]

If the compensator is working I'd get it pressure bleed with a bleeder ball. It bleeds/pushes from the calipers to the MC. Good shops use them for hyd clutches and such and it'll darn sure get any air out.