Random brake pedal travel issue

[rudi dudi]

Originally Posted by volvo again

According to the haynes manual, the master cylinder is not a servicable item and no repair kits are available...
I suppose there is a possible solution in replacing it with a good used one...whether your garage would agree to this is doubtfull...
If you're handy with spanners and can bleed brakes you could diy, not a hard job

Haynes is talking Ball ox as usual.. Seal kit are available and no different to Caliper repair kits in that instance.
Your new master cylinder will be a recon unit.
Is it worth the hassle is another question
Autodoc list a repair seal kit if your leaning that way..

[rudi dudi]

Originally Posted by Arnold Layne

Thanks Martin, I've done what you suggested and that's exactly what happened, very helpful of you.

I'll report it to my local independent mechanic and see what he says. Any thoughts from your experience on what they normally do to fix it? The V70's probably not worth a lot of money, so I hope he doesn't say he needs to replace the entire master cylinder.

Cheers for your help.

It's not a big job to replace the master cylinder 1.5 hrs tops and a replacement Master cylinder isn't a hugely expensive item £50 to £100 at most

[Jammin]

I've recently replaced my 850 master cylinder with a new ATE one bought from ebay, £116.96 delivered from Latvia. A straight forward swap using a few spanners and a Gunsons eezibleed.

[CNGBiFuel]

How is it no one asks WHY the MC has gone?
In good fluid, they last the life of the car.

New MC will be cheap enough. There's no way if you're paying standard labour rates anyone would even think to put a seal kit on. Seal kit is for any vaguely competent home-fixer, whereas the OP appears to want to pay to have this job done.
Why in all that's holy would he want to pay for a seal kit? And two hours labour?

My money is on old fluid getting wet, going acidic, this corrodes everything and rips-up seals, ABS units, calipers etc.

Dear, dear, somebody neglected to flush.

[Laird Scooby]

Originally Posted by CNGBiFuel

How is it no one asks WHY the MC has gone?
In good fluid, they last the life of the car.

My money is on old fluid getting wet, going acidic, this corrodes everything and rips-up seals, ABS units, calipers etc.

Dear, dear, somebody neglected to flush.

Totally agree on that. Ideally should be done every 2 years but as soon as is possible after that. Have to confess i'm late in doing mine on my 760 but plan to do it soon as i can.

[CNGBiFuel]

Why? 14 posts before anyone asked this question? That's quite worrying.

And if someone is paying me, and is worried about hte price of an MC, the MC gets done inside an hour. I'm paid by the job, and until customers tell me they want to pay more, shouldn't need bleeding. Hence the root to the problem [the acid others might call brake-fluid] stays put?

Give it until next MOT, ABS unit / seized calipers. Bill more than it's worth. One dead P80.

[Laird Scooby]

Originally Posted by CNGBiFuel

Why? 14 posts before anyone asked this question? That's quite worrying.

And if someone is paying me, and is worried about hte price of an MC, the MC gets done inside an hour. I'm paid by the job, and until customers tell me they want to pay more, shouldn't need bleeding. Hence the root to the problem [the acid others might call brake-fluid] stays put?

Give it until next MOT, ABS unit / seized calipers. Bill more than it's worth. One dead P80.

I'm more worried that you suggest after breaking the hydraulic systen open and allowing air in to replace the MC that you think it won't need bleeding?

[Jammin]

Originally Posted by CNGBiFuel

My money is on old fluid getting wet, going acidic, this corrodes everything and rips-up seals, ABS units, calipers etc.

You mean like this master cylinder:



causing the seal to fold over like this and locking the brakes on:



This was on my Audi 90. I changed the one on my 850 due to corrosion where the reservoir seal sits as it was sucking in air:



Yeah, change the fluid every 2 years

[Martin Cox]

A good point CNGBifuel. I didn't think to ask for a number of reasons:

The original post asked what may have gone wrong, not why.

I didn't think it unreasonable to expect some wear on the seals after 20+ years.

I've always changed my brake fluid every two years, initially at the Volvo Dealer during a service and latterly myself and it didn't occur to me that not everybody may do this. I've owned my V70 for nearly 20 years. I've always used a pressure bleeder so the pedal has never been beyond its normal travel range.

Brake parts, particularly ABS pumps, are expensive and fluid is cheap. It made no sense to me not to change the stuff regularly. (Thinks - I've got a new unopened 5 litre container of the stuff in the garage waiting to be used. I really must get on with it!)

The original poster may not have owned the car as long and may have inherited problems caused by others neglect.

Of course it would be good to know why the seals are failing but it's not unlikely that fluid may be a contributing factor.

Martin

[CNGBiFuel]

I'm more worried that you suggest after breaking the hydraulic systen open and allowing air in to replace the MC that you think it won't need bleeding?

OK, I must admit I've never had need to change a P80 MC. Changed MCs on quite a few vehicles over the years, and never needed to bleed anything. Pour fluid back in thru' the top and be done. Air comes back up thru' MC. Worst case, I've a MityVac. Force fluid in from the the bottom and as it rises, see it pop out the MC.

Back in the day you could get coloured brake-fluids, red/blue or Green. That helped.

I didn't think it unreasonable to expect some wear on the seals after 20+ years.

I've got the original MC on one 290K car. Should last the life of the car. Or replace 3-4 times more often than fluid, 'you pays your money'. See jammin's pix.

Unless a P80 is somehow different, the only reason I've ever done a bleed with an MC change,is because a flush is good practice... because we're on...