Brake Fluid Change or Test? - Chris M

The general view on here is, I believe, that brake fluid changes every 2 years is just a profit generating exercise by main dealers when in fact the fluid only really needs changing if the moisture content is too high.

So does anyone here own/use a brake fluid tester? Sealey sell one which does a boil test £400, so out of the question for DIY use, but Amazon have basic versions for under £10 including a Silverline one for £7 which looks identical to a Sealey branded one for nearer £30.

As these testers are safety related, I wouldn't want to use one which couldn't be relied on however, it would be easy enough to test/calibrate one by gradually adding water to fresh brake fluid. 4% water content is the 'danger' reading.

Brake Fluid Change or Test? - RT

Difficult, if not impossible to test - the moisture content in the flexible brake pipes can be considerably higher than that in the master cylinder.

Since my brakes are often the only thing between me and oblivion, I'll stay with paying for a 2-year change.

Brake Fluid Change or Test? - Wackyracer

It's so easy to just bleed some fresh fluid through every 2 years it's not worth trying to test. Adds just 30mins to service time doing it myself.

Brake Fluid Change or Test? - skidpan

Brake fluid does not flow around the pipework so sampling the mastercylinder does not tell you what the fluid is like in the pipes and calipers. Its not just moisture that affects fluid performance either, over the years the brakes get very hot and the fluid dehgrades and no tester will tell you about that.

Brake fluid is cheap and it does not take long to change so why skrimp.

As you go plummeting over a cliff you don't want to be thinking " that fluid tester was a waste of money".

Brake Fluid Change or Test? - gordonbennet

I've worked on hundreds of cars in my time, i have a bit of an OCD about brakes they have to be spot on lubed and working at least as well as they were when new.

You wouldn't believe the muck and filth that i've found in wheel cylinders and behind caliper pistons over the years on neglected systems, quite apart from the generally corroded and seizing caliper sliding or adjusting mechanisms, plus pipework covered in salt and filth doing its worse.

The cost of brake servicing is not wasted money, but i do mean servicing, not the modern idea main dealer peering at the things and a bit of brake cleaner being fired in the general direction, you cannot examine pads properly unless you remove them nor can you inspect shoes cylinders and adjusters via that little peer hole behind the rubber grommet on drums.

Get someone who actually gives a toss to service the system at least every other year, they can change the fluid at the same time, with the added bonus that you won't get seized bleed screws.

Brake Fluid Change or Test? - bathtub tom

You can test your brake fluid yourself: xlforum.net/vbportal/forums/archive/index.php/t-12...l

I use this method, but also bleed a little when I dismantle and lube the brakes each year.

Brake Fluid Change or Test? - skidpan

You can test your brake fluid yourself: xlforum.net/vbportal/forums/archive/index.php/t-12...l

I use this method, but also bleed a little when I dismantle and lube the brakes each year.

So you choose to use a method described on the internet instead of simply changing your fluid.

We all know the internet is full of total nonsense so why risk safety using a method of testing that as far as I know anyone has ever recomended other than a single internet geek.

If it were that simple garages would be doing it at every service and cgarging us 1/2 hours labour for printing off the result.

File that page under TOTAL B00llockS

Edited by skidpan on 24/07/2017 at 15:34

Brake Fluid Change or Test? - Chris M

That's how the basic testers work I think, but whether a reading of 0.3v is correct, I don't know.

As for my initial assertion regarding 2 yearly changes, I must be thinking of another forum (or maybe just another poster on this one!).

Brake Fluid Change or Test? - gordonbennet

Youre probably thinking of JohnF who's more than likely still braking on Girling Crimson fluid and full asbestos linings riveted on..

:-)

Brake Fluid Change or Test? - Wackyracer

Youre probably thinking of JohnF who's more than likely still braking on Girling Crimson fluid and full asbestos linings riveted on..

:-)

More likely to be dark brown and dirty ;-)

Brake Fluid Change or Test? - John F

Youre probably thinking of JohnF who's more than likely still braking on Girling Crimson fluid and full asbestos linings riveted on..

:-)

Actually, Bluecol would probably be perfectly satisfactory for UK roads where speeds now rarely rise above 60mph. Has anyone ever heard of any instances of brake failure due to boiling fluid this century, unless descending an Alp in a Mini pushed by a large caravan, or disporting themselves on a track day?

I happen to think too regular brake fluid change advice is a scam. All I do is expel a little fluid from the bleed nipple when changing pads. Even this is probably unnecessary. Water absorption these days is negligible because much effort goes into the design of the sealed system, and seals are much better than they used to be.

Brake Fluid Change or Test? - gordonbennet
Has anyone ever heard of any instances of brake failure due to boiling fluid this century, unless descending an Alp in a Mini pushed by a large caravan, or disporting themselves on a track day?

I just knew you'd be the dissenter John, and you never disappoint, though not sure as i'd be willingly filling the braking system with anti freeze.

No not this century but i did have total brake failure once in my sisters Wartburg Knight when almost new car, fortunately i've never been one for leaving braking till the last minute and the decent sized drum brakes also provided a more than adequate parking brake, so disaster was avoided.

I agree the systems are better now, unfortunately due to being so we now have a generation or more of car owners who don't think about regular maintenance so those better systems seize instead.

Brake Fluid Change or Test? - John F

I agree the systems are better now, unfortunately due to being so we now have a generation or more of car owners who don't think about regular maintenance so those better systems seize instead.

I think slave pistons seize because of too much 'maintenance', not too little. If you change pads and discs before they are fully worn, the piston never travels anywhere near the length of its cylinder.

Unscrupulous mechanics will play the safety card and tell ignorant people that four or five mm of remaining pad wear 'won't last till the next service, miss'. So the unused part of the cylinder never gets bathed in fluid and is more exposed to external corrosion, making more work for the mechanic when the piston eventually encounters it and seizes. I have always run old cars which get to a high mileage, and have never had their original pistons seize, or a disc disintegrate after I have carborundum wheeled the lips and ridges. A professional skimmer probably removed too much metal.

Brake Fluid Change or Test? - bathtub tom
Has anyone ever heard of any instances of brake failure due to boiling fluid this century,

Yes, once, when unbeknown to me, a previous owner had the discs skimmed. As the pads wore one piston came out further than intended and locked skew-whiff, putting gentle pressure on the pad. Driving at the national limit on a dual carriageway was enough to boil the fluid, resulting in the pedal hitting the floor on the approach to a roundabout.

Brake Fluid Change or Test? - gordonbennet

Yes, once, when unbeknown to me, a previous owner had the discs skimmed.

Only once did i get discs skimmed, resulted in the disc cracking not long after so ended up with new discs anyway, like so many things filed under won't do that again it seemed a good idea at the time.

Brake Fluid Change or Test? - Andrew-T

<< ... a previous owner had the discs skimmed. As the pads wore one piston came out further than intended and locked skew-whiff, putting gentle pressure on the pad. >>

That sounds like rather more than a 'skim'. I did once have disks skimmed on a fairly young 205 about 1990, after pulsation developed while braking. It cured the problem, but it slowly returned, so I assumed the disk metal was of variable hardness.

I also had the experience of driving a pool 309 with only about 16K on the clock, but the friction material on the pads was down to almost nothing, so the brakes made a horrible noise (none of the regular users were responsible for upkeep, and may not have thought about it, so nothing was done until I reported it). I drove that car from Worcester back to Cheshire using the gears to stop as far as possible.

Edited by Andrew-T on 28/07/2017 at 16:42

Brake Fluid Change or Test? - skidpan

As for my initial assertion regarding 2 yearly changes, I must be thinking of another forum (or maybe just another poster on this one!).

In my experience some makes have a 2 year interval, others 3 years. But its only a small part of your annual motoring costs. A fill up costs as much.

Brake Fluid Change or Test? - RobJP

For my car, BMW charge the terifying, astronomical sum of £71 to do a brake fluid change.

Yes, that's BMW dealership rates !

Is it worth your while wondering about how much moisture the brake fluid has (or has not) absorbed, and doing tests, and finding out which testers are worth buying ...

Brake Fluid Change or Test? - Wackyracer

Is it worth your while wondering about how much moisture the brake fluid has (or has not) absorbed, and doing tests, and finding out which testers are worth buying ...

Not when you can buy brake fluid for under £10 and do the job yourself for free, that's providing your proficient in doing the task of course.

Brake Fluid Change or Test? - RT

As for my initial assertion regarding 2 yearly changes, I must be thinking of another forum (or maybe just another poster on this one!).

In my experience some makes have a 2 year interval, others 3 years. But its only a small part of your annual motoring costs. A fill up costs as much.

VW work on the basis of first fluid change at 3 years then 2 yearly after - reasoning is that the intial fill is done with pristine components.

Brake Fluid Change or Test? - skidpan

Has anyone ever heard of any instances of brake failure due to boiling fluid this century, unless descending an Alp in a Mini pushed by a large caravan, or disporting themselves on a track day?

Only had it happen once on the road and that was back in 1978. Triumph Spitfire just a few months old and been out in the Derbyshire Peak with a lady friend. Dropping back down into Ashbourne the pedal started getting long and by the time we got into town i was getting seriously worried not only about the total lack of brakes but the smell of burning. They recovered over the next few miles after which they fine.

From buying the car the brakes had always seemed perfect with a firm pedal (no servo from memory) so I was surprised when they did what they did. Considering millions of cars had been fitted with the Girling Type 14 front caliper and the Spitfire was not exactly a heavy car there should not have been an issue. Car went into the garage and they did a fluid change and inspected all the parts after which the car never had another brake issue. All I could conclude was the factory at Canley had used a mixture of horses urine and fairy liquid instead of brake fluid when the built it.

10 years later I bought my first Caterham which was fitted with Girling type 14 calipers. That car had nearly twice the power of the Spitfire and saw some serious track action and never had a brake issue. The second Caterham also came fitted with Giorling type 14 calipers and that car at one point had 3 times the Spitfires power and again no brake issues.

But I still change the fluid every 2 years now, when I used it regularly on the track it was twice a year. The Type 14 calipers have now been replaced by a pair of huge 4 pot trackday calipers which are normally fitted to midified Civic tyre R's (still on solid discs). They give some seriously good braking.

Brake Fluid Change or Test? - craig-pd130

It's exactly how some testers work. They apply a known voltage in the fluid. As water is a conductor and glycol brake fluid isn't, the greater the water content, the more voltage is measured. However, different fluids have different additives, and some of these additives have a degree of conductivity which will vary from brand to brand, etc. So a 'boil' test is the only test that is truly accurate.

But as said, testing only usually gauges the condition of the fluid in the master cylinder, not in the slave cylinders or pipes.

My BGT V8 had sticking front calipers when I got it. On a drive, the car was pulling so badly I had to pull off the road. As I tried to come to a stop in the car park, the pedal went right to the floor, and only the handbrake stopped me. I got out of the car and the front offside brake pads were smoking like they were on fire.

After 20 minutes of cooling down, I had brake pressure back and was able to get home. The calipers were rebuilt the following weekend: crud build-up in the fluid seal groove was the cause of the sticking.

 

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