Brake fluid moisture content tester

[Pete Lewis]

I think thats ok, , and to stop breathing over storeage  some blue tack over the breather .

And dont forget to take it off,   put   a label on steering wheel

Pete

[Anglefire]

On 17/12/2018 at 10:49, Mjit said:

Can't say I see the point in brake fluid moisture testers.  If you can't remember the last time you change the fluid, it's time to change it.

With a bottle of DOT4 under £5 that should see you through 3 changes for less than the cost of the tester, and at a full change every 3 years that's 9 years of ownership - at which point the tester will either have broken/been lost/you'll have forgotten you bought one

Don't see the point of buying a bottle of brake fluid to sit on the shelf, opened for up to four years and replace the old stuff in the car. It won't have as much water in it, but for less than £5 I would buy new every change!

[dougbgt6]

I have a litre of silicone awaiting installation so I don't need a brake fluid  tester, but it will be fun frightening friends a relatives over the inadequacies of their braking systems. I shall take it to parties.

"Good evening madam, may I test your fluid?"

db

[Pete Lewis]

From my point of view its more for proving the  topic at club meets and the worst get s a prize 

Its suprising how many have no idea about the moisture , this just makes a talking point and proves a result

And  fluid kept in a Air Tight should remain good as new

Its the reservoir breather that takes in damp air and it doesnt stay  in the reservoir it does travel around the whole system

3% and  very hot pads spells a lost pedal  and a ditch 

[Colin Lindsay]

46 minutes ago, dougbgt6 said:

 

"Good evening madam, may I test your fluid?"

db

If it gets too high you'll find yourself in a layby somewhere, waiting on recovery....

[Pete Lewis]

make sure your in slippers and  PJ someone  will take him home 

 

[Herald948]

On 24/12/2018 at 04:53, Pete Lewis said:

And  fluid kept in a Air Tight should remain good as new

For whatever it's worth:

1. I've been told that once a container of fluid has been opened, it's really only good for a month or so.

2. Castrol themselves told me that, even in a never-opened container, their brake fluid only has a shelf life of about two years. Even the modern plastic bottles are apparently somewhat permeable! Who knew?

[Mjit]

Not sure I buy either of those life estimates.  How can the fluid only last a month or so in the bottle opened/2 years in the bottle unopened when the recommended life in a car is 2 years...

Exactly how does a car's plastic fluid reservoir (with breather hole) keep the fluid 20 time longer than an opened but re-capped (eithout breather hole) bottle and just as well as a capped bottle with a secondary air-tight seal over the opening?

[68vitesse]

1 hour ago, Herald948 said:

For whatever it's worth:

1. I've been told that once a container of fluid has been opened, it's really only good for a month or so.

2. Castrol themselves told me that, even in a never-opened container, their brake fluid only has a shelf life of about two years. Even the modern plastic bottles are apparently somewhat permeable! Who knew?

I'm not being cynical? more sales more profit.

Regards

Paul

[Anglefire]

6 hours ago, Mjit said:

Not sure I buy either of those life estimates.  How can the fluid only last a month or so in the bottle opened/2 years in the bottle unopened when the recommended life in a car is 2 years...

Exactly how does a car's plastic fluid reservoir (with breather hole) keep the fluid 20 time longer than an opened but re-capped (eithout breather hole) bottle and just as well as a capped bottle with a secondary air-tight seal over the opening?

I get your point - but also, the opened bottle has been exposed to the atmosphere - and if you were to use it to top up within the 2 years of a brake fluid flush, then that would be fine - at least as good as the fluid in the system, but if you use it to flush a system, you have no idea of the true moisture content, so don't know for sure how long it will be before it needs changing again.

An unopened bottle is a different kettle of fish - in theory that should last a good while.

[Colin Lindsay]

18 hours ago, Herald948 said:

2. Castrol themselves told me that, even in a never-opened container, their brake fluid only has a shelf life of about two years. Even the modern plastic bottles are apparently somewhat permeable! Who knew?

Wouldn't they leak all over the shelves, then? If moisture gets in, it also can get out.

[dave.vitesse]

Back in the 1960's I can remember the old boys, probably much younger than me now, heating up brake fluid to remove the moisture. Why the fluid didn't flash over and ignite I don't know.

A Very Dangerous thing to do.

No Health and Safety in those days.

Dave 

[Anglefire]

I remember an episode of top gear I think where they poured petrol on a hot exhaust manifold. It smoked a bit. 

They did the same think with brake fluid and it went up like a fire cracker. 

It’s why they cable tied a lot of reservoirs to the master cylinder - before they put them behind another bulk head in more modern times. 

[Pete Lewis]

we kept it bulk stored by the line side , think in excess of 200 gallons , it did have some membrane arrangement to keep it clean and ??? dry 

from days of testing we only checked stock vehicles , and results could be alarming

pete

[NonMember]

51 minutes ago, dave.vitesse said:

Back in the 1960's I can remember the old boys, probably much younger than me now, heating up brake fluid to remove the moisture. Why the fluid didn't flash over and ignite I don't know.

Probably because, if done right, it never reaches flash point, let alone auto-ignition. The former is somewhere above the boiling point of water, the latter is higher still - at least 250C. The Top Gear demonstration exposed the brake fluid to exhaust temperatures in excess of 300C. All you need to remove the water, in a generally dry environment, is 75C and some patience.

Still, I don't recommend the practice when new brake fluid is cheap, safe and guaranteed dry already!

[dave.vitesse]

The fluid was heated in a large open metal pot over a gas ring, that was the way back then. Most of the people had come through a war and there was a different attitude to risk than now.

It is correct you can remove the moisture by heating the fluid, but there would have to be far greater control of both the process and the conditions than above to do it safely. Why take a risk, just buy some new stuff as it's cheap enough now a days.

Dave

[JohnD]

This interesting chart is published by Shell, and as shown compares various DoT grades of brake fluid.    The US Dept. of Transport standards that define the DoT types include the "Wet Boiling Point" of brake fluid with 3.7% water included, to simulate fluid after about two years of use, as above.   Modern fluids not only have a higher boiling point straight from the can, but maintain the wet BP higher while more water gets in:

DoT 5, is , of course, silicone-based and non-water absorbing, BUT is more compressible than the glycol based flyids, AND will allow water to collect in the system as water, not in solution so that it will boil at just 100C!     It still needs relatively frequent changing.     I prefer DoT 5.1.

The heat of brake pads will vary by their use, and the material governs their effectiveness, let alone boiling brake fluid.     This chart shows how OEM pads are limited to less than 600C, while specialist materials can go much higher, and that heat has to go somewhere!  (I have no particular love of Hawk pads - but they produce this nice chart!)

 

[dougbgt6]

On ‎29‎/‎12‎/‎2018 at 15:29, JohnD said:

 It still needs relatively frequent changing

I don't believe that! Data please?!!

I don't like 5.1, it eats paint, the same as it's predecessors. 

Buckeye Triumphs do an excellent report on silicone fluid which lays to rest a lot of nonsense talked about silicone fluid. Interestingly the author puts it in his Triumphs, but not his moderns.  Silicone doesn't like ABS but more importantly insurance problems if you convert on a modern.

Doug

 

[Anglefire]

7 minutes ago, dougbgt6 said:

I don't believe that! Data please?!!

I have no data to add, but it stands to reason - any water that gets into the fluid will collect somewhere and reduce the efficiacy of the braking system as it will boil quite quickly and make steam. With the other dot’s The water is absorbed into the fluid so in theory at least remains more efficient. 

The rate of water ingress is the big unknown. 

[dougbgt6]

Mark,

If the water's in there it's going to turn to steam no mater what the fluid is. I recommend you read the Buckeye Triumph assessment of silicone brake fluid  to see how wonderful it is. 

Doug

 

[Anglefire]

I think I’ve read it before. I wasn’t convinced the pros outweigh the cons to be honest. 

You are right that water will boil whatever- but silicone fluid doesn’t absorb any so remains in the aqueous state. 

 

[Anglefire]

I've just looked again and it is one I've read before. It is interesting, but I still am not convinced that I would change over to it - at least not unless I was doing a complete system change. Something I did last year, so won't be repeating for a while yet!

Peddle feel is the other issue that I'm not sure I would be happy with - my brakes took a lot of bedding in (for whatever reason!) to get a nice firm peddle. If it was to remain soft, I would be concerned that there was an issue! 😂

Flushing the brake fluid through every couple of years is not a big deal. £5 or so in fluid and an hours work.

But each to their own.

[KevinR]

My take on the problem with Silicone fluid is as follows :

1. It does not absorb water, so any water getting into the system will remain as water, and not a molecular level mix of water and fluid.

2. Water is heavier than silicone brake fluid, therefore it will sink to the low point of the reservoir or pipe work it gets into.

3. With the water at the bottom of the reservoir, it will eventually get into the pipes going to the wheel cylinders.

4. Every time the brake pedal is pressed, the "slug" of water will be pushed forward in the pipe, and if it reaches a high point in the pipe it will then sink to the next low point.

5. The next time the brake pedal is pressed, the slug of water will move forward again.

6. Eventually the slug of water will arrive in the wheel cylinder, and will sink to the LOW point in the cylinder.

7. Wheel cylinders get hot during braking, and the water in the cylinder will boil at approximately 100 degrees Celsius, and the brakes will instantly fail.

8. No amount of bleeding the brakes will remove the water as the bleed nipples are at the top of the cylinders as AIR is lighter than the fluid so it rises.

9. Water in the wheel cylinders will also cause corrosion and may result in a cylinder seizure

10. To get the water out of the wheel cylinder it is necessary to remove the cylinder and invert it before bleeding so that the bleed nipple is lower most.

 

Having said the above, I still don't have a problem with using Silicone fluid - just be aware of the water "problem" and ensure that any water in the system is removed properly.

[Clive]

I can see what is being said, but as silicone fluid does not absorb water, the only way it should get into the system is carelessness (jetwashing the engine bay? spilling tea? something like that) Then there is the  question whether the small bore brake pipes are large enough to allow the "slug" droplet etc to actually move, or will it just stay in place (like a capillary tube). Some experimentation is needed if anybody is worried enough.

My biggest issues are twofold. I was sold some silicone fluid that was contaminated and I had to strip and re-rubber the entire system (it attacked the seals!) so although a reputable supplier should be OK, it still worries me having been bitten once. But the second issue is poor availability. When I am up the alps and a seal goes, I carry seal kits so can sort that, but what if I run out of silicone fluid? I may have to wait several days or get the car recovered. But conventional fluids available easily everywhere. Hence my choice (DOT4)

For showcars and so on silicone makes a sense. But the advantages boil down (sorry) to not attacking paintwork,( but making it very hard to repaint if that is ever required.) and not having to change the fluid every few years. However, how many silicone fluid users would get flummoxed at using a high quality fully synthetic engine oil that needed fewer changes? That really has no downsides at all...and has real benefits 

[johny]

Hi, couple of points:

I believe moisture can get into our systems via the breather hole on the master cylinder. This allows air (and any moisture it holds) in as the fluid level goes down due to operation of the pedal or even liquid volume change due to temperature.

Fully synthetic oil is great except that it needing less frequent oil changes doesnt allow for the greater rate of contamination due to poor combustion in older engines....