Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Shackeng on 19 July 2015, 11:59:35
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Has anyone removed and overhauled the master cylinder on a 3.2? It looks fairly straightforward in Haynes for the 3.0. If so any issues and are seal kits available for them? :y
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Normally pretty bulletproof... Has yours gone?
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Yep fairly easy to remove, but if needing to remove the brake pedal, and I think you do(?) then acquire a good replacement brake light switch first, as the tangs almost always break off on removal. Very very Brital
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Normally pretty bulletproof... Has yours gone?
Not gone Paul, but the Elite pedal has always been a bit soft compared to the TD, despite fluid change, brake bleeding etc. So i thought I would replace all the seals in the system, hoping for an improvement. :y
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Yep fairly easy to remove, but if needing to remove the brake pedal, and I think you do(?) then acquire a good replacement brake light switch first, as the tangs almost always break off on removal. Very very Brital
Thanks Chris, are the seals readily avlbl. do you know? :y
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Yep fairly easy to remove, but if needing to remove the brake pedal, and I think you do(?) then acquire a good replacement brake light switch first, as the tangs almost always break off on removal. Very very Brital
Thanks Chris, are the seals readily avlbl. do you know? :y
Sorry should of said, I have removed one. I have not opened one up in any way.
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Normally pretty bulletproof... Has yours gone?
Not gone Paul, but the Elite pedal has always been a bit soft compared to the TD, despite fluid change, brake bleeding etc. So i thought I would replace all the seals in the system, hoping for an improvement. :y
Could that be servo/vacuum related?
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Normally pretty bulletproof... Has yours gone?
Not gone Paul, but the Elite pedal has always been a bit soft compared to the TD, despite fluid change, brake bleeding etc. So i thought I would replace all the seals in the system, hoping for an improvement. :y
Could that be servo/vacuum related?
Hmm, how can I test for that?
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Normally pretty bulletproof... Has yours gone?
Not gone Paul, but the Elite pedal has always been a bit soft compared to the TD, despite fluid change, brake bleeding etc. So i thought I would replace all the seals in the system, hoping for an improvement. :y
Could that be servo/vacuum related?
Hmm, how can I test for that?
First question might be, is there a leak in the vac pipe? Especially where the clip holds the vac pipe away from the air con pipe by the scuttle drain.
They are known to wear through if the clip brakes or hoes missing as the two rub together.
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Normally pretty bulletproof... Has yours gone?
Not gone Paul, but the Elite pedal has always been a bit soft compared to the TD, despite fluid change, brake bleeding etc. So i thought I would replace all the seals in the system, hoping for an improvement. :y
Could that be servo/vacuum related?
Hmm, how can I test for that?
First question might be, is there a leak in the vac pipe? Especially where the clip holds the vac pipe away from the air con pipe by the scuttle drain.
They are known to wear through if the clip brakes or hoes missing as the two rub together.
I'll have a look, but as it's vac. it may be difficult to spot, unless a clip is missing :-\
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Ideally needs removal and examining, but it will likely hiss with engine running.
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Ideally needs removal and examining, but it will likely hiss with engine running.
The master cylinder or vac pipe? :-\
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Ideally needs removal and examining, but it will likely hiss with engine running.
The master cylinder? :-\
No, vac pipe.
Does the pedal sink at stand still on tickover?
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Can't remember, I think yes, but will check. Is this a good or bad sign?
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Can't remember, I think yes, but will check. Is this a good or bad sign?
Might be a vac leak in the plenum to servo pipe. Might be servo diaphram (?thingy) leaking inside the servo itself.
But servo pipe is quite common to chaif through and leak. :)
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Can't remember, I think yes, but will check. Is this a good or bad sign?
If the pedal sinks when the brakes are applied but you are not losing fluid then that does point to the seals in the master cylinder (so not ideal)
Good servo assistance tends to amplify any sponginess because you can apply more brake pressure without pressing very hard on the pedal. Try pressing the pedal without the engine running to feel what a rock hard pedal feels like (try it while moving and needing to stop to feel what brown trousers feel like ;D)
I think Chris is suggesting that you check things that are needed to stop safely but which make the pedal feel harder when they are not right.
I think you should look at flushing all the brake fluid from the system then bleeding the ABS pump and/or replacing the brake flexi hoses if you don't get a result from servicing the master cylinder. It is quite startling how much the hoses can swell during a brake test but people don't give them a second thought.
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Strange if the hoses are degraded, as the brakes are exactly the the same, slightly spongy, despite the works mentioned, as when I bought it 4 years ago at 48k, and it is now only 57k. I'm inclined to think it is leaking seals somewhere but will check the vac for leaks. My TD which is 2 years older on 126k has rock solid brakes! :y
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Bah. Sorry. Andy making more sense here. :y
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Can't remember, I think yes, but will check. Is this a good or bad sign?
If the pedal sinks when the brakes are applied but you are not losing fluid then that does point to the seals in the master cylinder (so not ideal)
Good servo assistance tends to amplify any sponginess because you can apply more brake pressure without pressing very hard on the pedal. Try pressing the pedal without the engine running to feel what a rock hard pedal feels like (try it while moving and needing to stop to feel what brown trousers feel like ;D)
I think Chris is suggesting that you check things that are needed to stop safely but which make the pedal feel harder when they are not right.
I think you should look at flushing all the brake fluid from the system then bleeding the ABS pump and/or replacing the brake flexi hoses if you don't get a result from servicing the master cylinder. It is quite startling how much the hoses can swell during a brake test but people don't give them a second thought.
I should have mentioned, I have no worries about stopping, and if I only had the one car would probably not have noticed the difference, it just requires more pressure than the TD, and feels slightly spongy. :y
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It might be worth bearing in mind that the TD and V6 have very different vacuum sources to power the servo. TD uses a vacuum pump, and V6 the engine maifold vacuum. It's entirely possible that this gives a different level of assistance in the first place.
If you have leaking seals, you should be able to press the pedal, and feel it slowly creep down over time as fluid leaks past the seal. If this doesn't happen, I'd say the seals are probably fine.
The other possibilities (no creeping pedal) are air in the system somewhere or bulging flexible pipes, as has been mentioned.
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It might be worth bearing in mind that the TD and V6 have very different vacuum sources to power the servo. TD uses a vacuum pump, and V6 the engine maifold vacuum. It's entirely possible that this gives a different level of assistance in the first place.
If you have leaking seals, you should be able to press the pedal, and feel it slowly creep down over time as fluid leaks past the seal. If this doesn't happen, I'd say the seals are probably fine.
The other possibilities (no creeping pedal) are air in the system somewhere or bulging flexible pipes, as has been mentioned.
I assume this is with engine running Kevin? :-\
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Just to add a question (which may help the OP) - are all master cylinders the same/interchangeable? Just wondering if a low mileage 2003 3.2 would bang straight on an L reg 2.0 8v etc... ?
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Engine off I think... pump pedal until solid, then press and hold. If it softens or sinks further the seals are shot allowing for the two exceptions given above :y
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Just to add a question (which may help the OP) - are all master cylinders the same/interchangeable? Just wondering if a low mileage 2003 3.2 would bang straight on an L reg 2.0 8v etc... ?
I seem to remember the design of them being different and requiring the pipes to be moved/extended.
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Hmmm, ok. :) FLs have a brake boost feature, don't they? Something that gives a shorter stopping distance? Or is it just in a larger Servo, perhaps?
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Just to add a question (which may help the OP) - are all master cylinders the same/interchangeable? Just wondering if a low mileage 2003 3.2 would bang straight on an L reg 2.0 8v etc... ?
I seem to remember the design of them being different and requiring the pipes to be moved/extended.
The differences primarily being whether three or four channel ABS and piston size being different according to both age and application iirc :-\
Haynes gives basic specs and without looking, different for pre, mid and post facelift and also for engine variation... so age and fuel both play a part ;)
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Hmmm, ok. :) FLs have a brake boost feature, don't they? Something that gives a shorter stopping distance? Or is it just in a larger Servo, perhaps?
Two stage master cylinder, but bear in mind my previous post :y
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Diagnostic testing:
Engine off pedal is firm.
Start engine with pedal pressed, pedal sinks slowly and applies brakes.
Pump pedal to firm it up, but fails to hold firmly and still sinks.
Braking hard while driving, car stops fine but requires more pressure than I would like.
I think its seals somewhere.
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Diagnostic testing:
Engine off pedal is firm. Does it stay firm if held down?
Start engine with pedal pressed, pedal sinks slowly and applies brakes. Normal, due to vacuum assistance.
Pump pedal to firm it up, but fails to hold firmly and still sinks. Normal, due to vacuum assistance.
Braking hard while driving, car stops fine but requires more pressure than I would like. A misconception, bourne out by driving cars with greater levels of assistance. These are perceived to have better brakes because the initial bite is sharper... also a misconception.
I think its seals somewhere. Replace fluid and bleed thoroughly. Report back.
;)
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Diagnostic testing:
Engine off pedal is firm. Does it stay firm if held down?Yes
Start engine with pedal pressed, pedal sinks slowly and applies brakes. Normal, due to vacuum assistance. :-\
Pump pedal to firm it up, but fails to hold firmly and still sinks. Normal, due to vacuum assistance.Hmm, OK, but does not feel right
Braking hard while driving, car stops fine but requires more pressure than I would like. A misconception, bourne out by driving cars with greater levels of assistance. These are perceived to have better brakes because the initial bite is sharper... also a misconception.Hard to describe, but please accept that 60 years driving experience tells me that the brakes on this car are abnormally spongy
I think its seals somewhere. Replace fluid and bleed thoroughly. Report back.Already done, see post#3
;)
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I would replace hoses and rebleed then... if the pedal holds pressure engine off, then the seals are fine.
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I would replace hoses and rebleed then... if the pedal holds pressure engine off, then the seals are fine.
I still find it hard to believe that the hoses have gone so soft on such a low mileage car. It only did 18k in its first eight years, so I suspect either seal hardening or lack of fluid changing in that period may have caused the seals to deteriorate. :y
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So the seals can go hard from lack of use, yet the hoses, exposed to uv light and weather cannot degrade at all?
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Engine off I think... pump pedal until solid, then press and hold. If it softens or sinks further the seals are shot allowing for the two exceptions given above :y
Best to do this test with the engine running, so you can exert normal pressure on the master cylinder with assistance.
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Engine off I think... pump pedal until solid, then press and hold. If it softens or sinks further the seals are shot allowing for the two exceptions given above :y
Best to do this test with the engine running, so you can exert normal pressure on the master cylinder with assistance.
But won't that give an ambiguous result by virtue of the continuous vacuum :-\
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If you have the engine running, and apply normal braking pressure, then hold it for maybe a minute or more, does the pedal continue to sink after the initial application of the brakes?
Might be worth trying another V6 if someone amenable is nearby, just to make sure it's not "TADTS".
Also, if the car does minimal miles, it's possible that the brake friction surfaces have got a bit glazed, I suppose.
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Engine off I think... pump pedal until solid, then press and hold. If it softens or sinks further the seals are shot allowing for the two exceptions given above :y
Best to do this test with the engine running, so you can exert normal pressure on the master cylinder with assistance.
But won't that give an ambiguous result by virtue of the continuous vacuum :-\
No. All you're checking is that if the master cylinder has a constant force on it, and therefore you have constant pressure in the braking system downstream of it, you don't get leakage out of the system. Any leakage and the volume of fluid in the system reduces and you have to move the pedal down to keep the pressure exerted.
All the servo is doing is using engine vacuum to increase the pressure on the MC. The pedal still moves with the MC's piston, so the test is valid with the engine on, it's just that it greatly increases the effort you can exert on the MC piston.
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You cant compare the two vehicles as the 3.2 has the power stop servo which gives a more progressive brake pedal
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So the seals can go hard from lack of use, yet the hoses, exposed to uv light and weather cannot degrade at all?
It would be interesting to know if this is common, on any vehicle, I have heard of it but suspect it is rare on low mileage cars. Are modern brake pipe materials are more prone to softening? I have had to change these for becoming hard and brittle with age on an old Ford once many years ago, I think it was a Cortina :-\
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If you have the engine running, and apply normal braking pressure, then hold it for maybe a minute or more, does the pedal continue to sink after the initial application of the brakes?
Might be worth trying another V6 if someone amenable is nearby, just to make sure it's not "TADTS".
Also, if the car does minimal miles, it's possible that the brake friction surfaces have got a bit glazed, I suppose.
Yes. :y
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So the seals can go hard from lack of use, yet the hoses, exposed to uv light and weather cannot degrade at all?
It would be interesting to know if this is common, on any vehicle, I have heard of it but suspect it is rare on low mileage cars. Are modern brake pipe materials are more prone to softening? I have had to change these for becoming hard and brittle with age on an old Ford once many years ago, I think it was a Cortina :-\
Net to bugger all UV light can get near them, rubbers can suffer from oxidisation but I suspect the effect you are experiencing is the power stop servo.
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So the seals can go hard from lack of use, yet the hoses, exposed to uv light and weather cannot degrade at all?
It would be interesting to know if this is common, on any vehicle, I have heard of it but suspect it is rare on low mileage cars. Are modern brake pipe materials are more prone to softening? I have had to change these for becoming hard and brittle with age on an old Ford once many years ago, I think it was a Cortina :-\
Net to bugger all UV light can get near them, rubbers can suffer from oxidisation but I suspect the effect you are experiencing is the power stop servo.
Can you tell me anything more about this Mark? where is it, can it be fixed easily etc./ :-\ :y
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Seem to remember a tis entry explaining a two stage level of assistance. The first stage being very gradual to keep the chauferd gent in the back happy. Yet if the driver stamps on the brakes he gets more assistance in an emergency.
I guess Marks post implies your symptoms are entirely normal if that's the case. And I need to fit a servo off a TD to get rid of the shite pedal feel on mine. :)
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Exactly, the facelift received a two stage power stop servo which gives a gradual pedal but a bucket load of additional assist if you press harder.
Cant comment on if the earlier servo is a direct replacement (probably is knowing GM)
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I guess I need a FL V6 owner to try mine for comparison. Thanks for all the input guys, very informative and helpful as usual.
I would be glad to know if anyone has experienced these bulging brake pipes on their Omega described above. :y
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Seem to remember a tis entry explaining a two stage level of assistance. The first stage being very gradual to keep the chauferd gent in the back happy. Yet if the driver stamps on the brakes he gets more assistance in an emergency.
I guess Marks post implies your symptoms are entirely normal if that's the case. And I need to fit a servo off a TD to get rid of the shite pedal feel on mine. :)
I guess you would have to fit the vac pump as well, unless the V6 engine vac would do it. I must agree that I prefer the instantaneous feel of the TD pedal, as opposed to the graduated feel of the V6, even supposing that mine is actually normal. :-\ :y
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Presumably to fit the pump you would need to carefully consider the rest of the manifold driven vac systems :-\
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No big difference on the vac setups, there is plenty of vac at idle on the V6 to create an effective pull down.....assuming its running right.....
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I had someone press the brake pedal hard with engine running, and none of the brake hoses have any significant alteration in diameter, (less than 1mm on a vernier caliper), just feeling them it was imperceptible. I find it difficult to believe that this will have much effect in braking efficiency. :y
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I had someone press the brake pedal hard with engine running, and none of the brake hoses have any significant alteration in diameter, (less than 1mm on a vernier caliper), just feeling them it was imperceptible. I find it difficult to believe that this will have much effect in braking efficiency. :y
I thought you said that was not the stopping ability that concerned you as much as the pedal feel? :-\
The hoses will extend as well as bulge and the outward appearance won't tell you much about the internal condition of the hoses or what type of reinforcement was used. I have a personal hatred of 'hose clamps' as I cannot believe that they don't damage the make up of the hoses.
Changing the flexible hoses on the motorbikes I owned in the 1980s made a massive difference in feel but that doesn't necessarily translate to a car :-\
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I had someone press the brake pedal hard with engine running, and none of the brake hoses have any significant alteration in diameter, (less than 1mm on a vernier caliper), just feeling them it was imperceptible. I find it difficult to believe that this will have much effect in braking efficiency. :y
I thought you said that was not the stopping ability that concerned you as much as the pedal feel? :-\
The hoses will extend as well as bulge and the outward appearance won't tell you much about the internal condition of the hoses or what type of reinforcement was used. I have a personal hatred of 'hose clamps' as I cannot believe that they don't damage the make up of the hoses.
Changing the flexible hoses on the motorbikes I owned in the 1980s made a massive difference in feel but that doesn't necessarily translate to a car :-\
Correct, I can't think why I wrote that. To rephrase, the pedal feels the same, spongy, even though the hoses don't seem to expand much. :y
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I have owned over 20 of these vehicles over the years plus numerous original 1994 - 8 3.0 and the mini facelifts also.
The pedal "travel" varies from car to car as does the pressure req to stop regardless of bleeding etc....the biggest variable is make of front brake pad with the oe jurid "gold dust" pads giving best feel and lowest pressure ,trade club and pagid/ate somewhere in the middle and trade club depending on whether the are made in india or Poland requiring higher pressure.
Second biggest variable is making sure your rear pads are not partially seized in the caliper,this also leads to increased pedal travel....
Would not rec rebuilding your m cy, it will not make a jot of difference, spend 70 pounds on some oe jurid pads from vx.....
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I have owned over 20 of these vehicles over the years plus numerous original 1994 - 8 3.0 and the mini facelifts also.
The pedal "travel" varies from car to car as does the pressure req to stop regardless of bleeding etc....the biggest variable is make of front brake pad with the oe jurid "gold dust" pads giving best feel and lowest pressure ,trade club and pagid/ate somewhere in the middle and trade club depending on whether the are made in india or Poland requiring higher pressure.
Second biggest variable is making sure your rear pads are not partially seized in the caliper,this also leads to increased pedal travel....
Would not rec rebuilding your m cy, it will not make a jot of difference, spend 70 pounds on some oe jurid pads from vx.....
Useful info, thanks. :y