Brake fluid

[Frenchtone]

Ok, can't find my manual, just got a letter from Skoda re brake fluid change now due, am I correct thinking its a Dot 4 fluid?

Edited 12 January, 2017 by Frenchtone

[octyal]

Yes, that is the standard fluid. You could "upgrade" to DOT 5.1 (I think) which is basically just a higher boiling point, so better for higher performance cars or those that tow a lot

[Carlodiesel]

D.I.Y

 

Change fluid when replacing brake pads.

Sorted.

Yes DOT4 

[rum4mo]

Might need to be hard on the brakes or high on mileage to make sure that the fluid change coincides with brake pad changing!

 

What is the VW group suggested change period, after first 3 years then every 2 years from then on?

 

Edit:- maybe a bit cold right now for doing that job DIY, I'd save it for a few months later!

Edited 12 January, 2017 by rum4mo

[Frenchtone]

Yeap approaching 3 years old , covered 28k, car was 6 mnths old when bought as a pre reg lump!

[Ryeman]

Oil companies have online specs if in doubt, Penrite being my preferred

[eribaMotters]

Forgive any spelling mistakes.

I'm not sure if I'm being a bit prehistoric on my views, but I cannot understand the need to replace brake fluid at set intervals. I thought the change should be when needed due to degredation of the fluid. It is anhydrous, that is absorbs water, but the absorption rate must differ between vehicles and be dependent upon many factors. If you did a specific gravity test using a hydrometer you should be able to determine whether the fluid needs replacing.

I appreciate that with the advancements in brakes and anti-lock set-ups that modern systems are more "delicate", but surely the fluid can remain unless it needs to be or changed.

 

Colin

[Ryeman]

I would open the nipples and push the pad back in order to get rid of the most suspect fluid - that in the calliper, as a priority.

[Llanigraham]

Forgive any spelling mistakes.

I'm not sure if I'm being a bit prehistoric on my views, but I cannot understand the need to replace brake fluid at set intervals. I thought the change should be when needed due to degredation of the fluid. It is anhydrous, that is absorbs water, but the absorption rate must differ between vehicles and be dependent upon many factors. If you did a specific gravity test using a hydrometer you should be able to determine whether the fluid needs replacing.

I appreciate that with the advancements in brakes and anti-lock set-ups that modern systems are more "delicate", but surely the fluid can remain unless it needs to be or changed.

 

Colin

 

But most owners wouldn't know how to do that, wouldn't have the equipment, and most importantly, wouldn't be arsed, therefore it is safer to say at a set period.

Plus it can degrade at different rates; I bet mine gets more water vapour into it than does someone in a dry area.

Note, that every car manufacturer other than those that use who use non-hydrosopic fluid, seem to state the same periods.

[Sad555]

Just reminded me why I got married..................someone to gently pump the breaks while I bled them with a plastic tube into a old sauce bottle.

[Ryeman]

Just reminded me why I got married..................someone to gently pump the breaks while I bled them with a plastic tube into a old sauce bottle.

That's ok on a relatively new vehicle, but if not done that way regularly, on an old one, there is a real risk of damage to the seal from operating in an old corroded area and starting a leak, then needing a renewed/new master cylinder kit

That's been my hard earned experience at least

(Eg clutch doesn't have that problem because it's 'polished' constantly)

Edited 12 January, 2017 by Ryeman

[Sad555]

RYEMAN..........I'd be a bit surprised if they still do cylinder repair kits ,master or slave ,I'm talking about over 40 years ago when I could hone out the old cylinders and fit a repair kit,good as new.

Edited 12 January, 2017 by Sad555

[Ryeman]

I'm more into not having to do any repair, by avoiding the potential damage

I'm still in the past though

[edwards]

Pressure bleed kit is one of the best things I' ve bought for DIY. I have the Gunson easi-bleed and its excellent. No pumping, no need for an assistant, can change the fluid just by running it through.

[Ryeman]

I've got a suction type bleeder but would prefer pressure which would need a suitable cap I guess as the plastic ones don't make a home system as easy as a metal cap of old.

[weasley]

Brake fluid is hygroscopic (rather than 'anhydrous', which means 'dry' or 'without water'). Over time it does absorb water which lowers the boiling point. In a testing programme a few years ago where I work, employees' cars were tested voluntarily and around 50% had boiling points that were approaching or below a level which needed action.

Normal fluid is DOT 4. DOT 5.1 is a compatible but largely unnecessary upgrade. If you want to go fully overboard you can use Castrol SRF, which has a phenomenally high wet and dry boiling point and is compatible with conventional systems and fluids.

Edited 13 January, 2017 by weasley

[Frenchtone]

Thanks for the responses, it will be a springtime job, as, living by the sea there is lots of salt in the winds/breezes which may or may not get into the system, the salt however does play havoc with the discs on my Marlin kitcar!

I will be using an Eezi-bleed to do said change, its brilliant, used it in September to bleed the hydraulic system on the Marlin having re sealed all the brake cylinders subsequent to an advisory on the controlle technique of a slight bind on the front nearside slave cylinder, once changed and with all new discs is now ok! Car will now stop in the proverbial sixpence!!   ; - D))

[rustic]

Pressure bleed kit is one of the best things I' ve bought for DIY. I have the Gunson easi-bleed and its excellent. No pumping, no need for an assistant, can change the fluid just by running it through.

Yes I have one of those, but I didn't have a cap for my Nissan 4x4. so a quick visit to scrap yard... then modified it to be like the others.

What I do, is remove as much of the fluid out of the resevoir as possible, a turkey baster is good here, then carefully add new, leave it a few hours for any bubbles to come out, but cap the resevoir, then start the bleed process.

Oh and don't forget the clutch, as that can soon look very black if left too long. Clealy not as critical as the brake fluid, but if it has absobed water, then corrosion can occur.

TIP keep a spray bottle of tap water handy, if you splash some fluid, do not wipe it off or you'll take the paint off, just simply wash with water.

Yet another tip... the old fashioned way to bleed brakes was one person in the car pumping the brakes, down, stop, release etc but I have heard a few horror stories, if you put the pedal to the floor, you are pushing the master cylinder seals to boldly go where no other seal has gone before... this can push the seal over unsmooth bores, damage them or worse, invert them, this might require a new or reconditioned master cylinder. So what I do as a precaution, is place a brick or similar, wrapped in a bag or cloth to save scatching the brake pedal, place it under the pedal, and this allows the brake pedal to only go down say 50-60% of travel.

Takes longer with short pumps, but it was good for me lol.

To be fair, in the old days of minis, Ambassadors, land rovers etc I never had a problem with full pedal travel, maybe I was lucky.

I just thought I would mention it.

Richard

[Ryeman]

Re the last part, that's been my experience. You might get away with it on a relatively new and well maintained car but it's almost inevitable on an old banger or one without a full service history.

[octyal]

Yes I have one of those, but I didn't have a cap for my Nissan 4x4. so a quick visit to scrap yard... then modified it to be like the others.

What I do, is remove as much of the fluid out of the resevoir as possible, a turkey baster is good here, then carefully add new, leave it a few hours for any bubbles to come out, but cap the resevoir, then start the bleed process.

Oh and don't forget the clutch, as that can soon look very black if left too long. Clealy not as critical as the brake fluid, but if it has absobed water, then corrosion can occur.

TIP keep a spray bottle of tap water handy, if you splash some fluid, do not wipe it off or you'll take the paint off, just simply wash with water.

Yet another tip... the old fashioned way to bleed brakes was one person in the car pumping the brakes, down, stop, release etc but I have heard a few horror stories, if you put the pedal to the floor, you are pushing the master cylinder seals to boldly go where no other seal has gone before... this can push the seal over unsmooth bores, damage them or worse, invert them, this might require a new or reconditioned master cylinder. So what I do as a precaution, is place a brick or similar, wrapped in a bag or cloth to save scatching the brake pedal, place it under the pedal, and this allows the brake pedal to only go down say 50-60% of travel.

Takes longer with short pumps, but it was good for me lol.

To be fair, in the old days of minis, Ambassadors, land rovers etc I never had a problem with full pedal travel, maybe I was lucky.

I just thought I would mention it.

Richard

 

You may be surprised at how many garages we talk to don't know about changing brake fluid as per the usual 2 year specification - and contaminated/old fluid is one of the leading causes of clutch hydraulic failure after having repair work done. The old fluid contaminates the seals, causing them to swell and fail prematurely.

[Carlodiesel]

When I had my garage, I had the B/Fluid testing machine.

What a waste of money.

I tested fluid from a 2 yr old car, and Fresh Fluid from a sealed container.

There was so little difference, it was not worth changing the fluid.

Several tests over time showed very little diff' in new & old fluids tested.

 

Unless other things were to cause a fluid change, I used the rule of thumb, change brake pads, change fluid.

 

 

On a side note. Has anyone ever had a brake failure due to fluid water contamination alone?

[rustic]

...

 

On a side note. Has anyone ever had a brake failure due to fluid water contamination alone?

If I was doing a track day at Silverstone, or long mountain descents then It would be sensible to renew the brake fluid more often.

Even heavy towing can also overheat the calipers, if the fluid gets really hot, then any moisture could turn to steam, which will render the brakes useless.

On race days, you often see brake discs glow red hot, in fact this is where ceramic discs come into their own.

Some of this heat will be transferred into the calliper as the friction pads are very hot too.

I guess if you have a brake calliper partially seize, and you didn't notice, then that caliper could overheat and boil off any moisture, killing the brakes and maybe all passengers in the car.

[weasley]

Another effect of the absorption of water is that it promotes hydrolysis of the fluid; that is the reaction of the fluid with water to form undesirable reactants which can cause deposits and corrosion. So even if the fluid doesn't boil, it does get hot, and with water in it the heat can drive the hydrolysis reaction faster.