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[Shackeng]

Having eliminated,:- discs, pads, fluid change, stuck pistons, I still have somewhat spongy brakes on the Elite, and having read previous posts, would like to check for air in the ABS. Is it possible to run the ABS pump without Tech 2, possibly by applying external power?

[freecall666]

have you checked for an air leak, had vectra and it was an air leak at fault, turn'd out to be the joint in the line.

[Kevin Wood]

Could be master cylinder seals, I suppose. Could they have been inverted when winding the pistons in? I'd say air in the ABS is unlikely, unless air has been allowed into it during work.

I don't know of a way to bleed it without a tech 2. Could try actuating it a few times on a quiet road (both ABS and traction control) then re-bleeding?

[Shackeng]

Could be master cylinder seals, I suppose. Could they have been inverted when winding the pistons in? I'd say air in the ABS is unlikely, unless air has been allowed into it during work.

I don't know of a way to bleed it without a tech 2. Could try actuating it a few times on a quiet road (both ABS and traction control) then re-bleeding?

Is this common on these cars Kevin? I haven't come across it before.

[jb]

Most common cause of this on the Omega is partially siezed rear calipers and or pads in the carrier!

[Kevin Wood]

Could be master cylinder seals, I suppose. Could they have been inverted when winding the pistons in? I'd say air in the ABS is unlikely, unless air has been allowed into it during work.

I don't know of a way to bleed it without a tech 2. Could try actuating it a few times on a quiet road (both ABS and traction control) then re-bleeding?

Is this common on these cars Kevin? I haven't come across it before.

A few members have had this problem. If the pistons are wound back in without opening a bleed nipple to expel the fluid in the cylinder, it can build up pressure in the master cylinder and flip the seals. Symptoms are then a spongy pedal.

Can sometimes be reversed by hitting the master cylinder with a hammer while releasing the pedal.

Has the spongy pedal appeared immediately after work being carried out on the brakes?

[feeutfo]

It takes a farely disastrous air leak into the system, like a caliper piston falling out, for air to get to the abs pump.

My feeling on flipping the seals is one of an oof myth IMO. But until disproved it has to be taken seriously I guess. Seems to me if the seal can indeed be 'flipped' then it can be flipped back again. No?

Recomended way to bleed the fluid is to open the bleed nipple while pushing the pads back in. Allowing the fluid to escape, rather than force it backwards up the system.

Sticking sliders might be worth a check, of not already. But if they where ok before...

[Shackeng]

Could be master cylinder seals, I suppose. Could they have been inverted when winding the pistons in? I'd say air in the ABS is unlikely, unless air has been allowed into it during work.

I don't know of a way to bleed it without a tech 2. Could try actuating it a few times on a quiet road (both ABS and traction control) then re-bleeding?

Is this common on these cars Kevin? I haven't come across it before.

A few members have had this problem. If the pistons are wound back in without opening a bleed nipple to expel the fluid in the cylinder, it can build up pressure in the master cylinder and flip the seals. Symptoms are then a spongy pedal.

Can sometimes be reversed by hitting the master cylinder with a hammer while releasing the pedal.

Has the spongy pedal appeared immediately after work being carried out on the brakes?

No, they have always been softer than the TD which has instant response to pedal push. It stops fine with a single push, it just works better with a slight pump.
As said, I have bled them twice, replace fluid, checked for sticking pistons, but will check the fronts again, which were OK when last checked about 4 months ago.

[Shackeng]

It takes a farely disastrous air leak into the system, like a caliper piston falling out, for air to get to the abs pump.

My feeling on flipping the seals is one of an oof myth IMO. But until disproved it has to be taken seriously I guess. Seems to me if the seal can indeed be 'flipped' then it can be flipped back again. No?

Recomended way to bleed the fluid is to open the bleed nipple while pushing the pads back in. Allowing the fluid to escape, rather than force it backwards up the system.

Sticking sliders might be worth a check, of not already. But if they where ok before...

I have just never come across this before, so was somewhat surprised to learn that it happens to Omegas.

[Shackeng]

Is there any way to remove/refit the master cylinder while preventing air ingress into the ABS?

[feeutfo]

Oh so we're talking about general performance, rather than a problem induced by the work...?

If so are the pads and discs the same..? Any servo vac problems or leaks in the vac pipe?

[Kevin Wood]

I would expect more pedal pressure to be required if there's a servo issue, and for the pedal to feel firmer, to be honest.

It is worth bearing in mind that the TD uses a vacuum pump to operate the servo whereas on the V6 it's engine intake vacuum. Might result in the feel being different?

The description of needing a "pump" does make me think that it's a master cylinder issue.

I would have thought you should get away with changing the master cylinder without an ABS bleed, but have never tried it.

Your chances would probably be maximised by "bleeding" each circuit at the outlet to the master cylinder (loosen the union while pressing the pedal down, then tightening it and lifting off) until fluid has filled the cylinder. This way, you'll get less air into the rest of the system.

[Radar]

If you're talking about having to push the pedal further down but the brakes work ok then i remember reading on here someone adjusted the height of the brake pedal to make it respond with less of a push. You also have to readjust the brake light. I will try and find the info.

[TheBoy]

Not sure who's closest, but might be worth a tech2 to check for air in any caliper.

Also, defo worth investigating jb's suggestion above - he has had and Omega or 2

[Andy B]

What had felt like spongy brakes on mine turned out to be springy brakes which was due to fubar'd discs. I note that you've said you've checked the discs, but what are the inward side of them like? I failed to notice that mine were like ..........

New discs & pads cured my iffy brake pedal.