Moisture in brake systems?

alan_m explained on 18/09/2018 :

Sorry, but that has not been my experience at all and I buy lots of minor items from Chinese sellers, in China and those suggesting they are in the UK. Everything has always been delivered within the described time frame. I am surprised about how little goes astray on the way here.

IME 'lie' is a bit strong. I've had maybe a dozen items from China. Longest a couple of months (and within the estimate), shortest a couple of weeks. Big retailers like Gearbest quickest, ebay slowest.

If you follow the tracking I'm not surprised sellers have to be cagey - so many things out of their control.

What does surprise me (alas) is how I've only had one item not turn up. And that was refunded without question, *and* a replacement sent.

No, lie is exactly what I mean. Items have been listed as being in the UK and will be dispatched by Royal Mail 2nd class with a 4 day estimated delivery. What's arrived weeks later are items from China.

I don't mind longer deliveries if they list the item as being from China but having paid much more for a quicker delivery from a UK seller I'm not impressed if it then arrives from the far east.

Harry Bloomfield formulated on Wednesday :

This turned up this morning, the quality seems quite reasonable.

So, OOI, what do your fluids read?

Cheers, T i m

I thought no one would ask :D

;-)

So, ideally 0% but I wonder how long it would take to get from there (fresh fluid) to 1% and what impact that might have ITRW?

According to what I read online, these fluids are chemical concoctions that contain corrosion inhibitors and that these 'packages' also degrade over time. I also understand that the insides of the steel brake pipes are lined with copper and that this can be corded away and so would be found in the fluid, potentially making it more conductive?

Of course, neither water nor dissolved copper are 'good things' to be found in brake fluid but I was wondering if dissolved copper might influence the reading of water at all (or even at it's highest concentration it still wouldn't register etc)?

Obviously a much shorter / simpler system. Are they both of the same age do you know (if this was a newish car it may not have had brake or clutch work done or fluids changed etc).

Assuming these gadgets are designed to reflect the genuine increased risk of having water in your vehicle fluid(s), then whilst 1% is on the upper level of 'No need to change', I wonder what the RW risk (of corrosion) is (compared with 0 or 4% etc)?

Snake oil or genuine issue etc?

Cheers, T i m

T i m submitted this idea :

The legend on this gadget suggests - It has a series of LED's green 0%, yellow 1%, yellow 2%, red 3%, red

Green is fine, two yellow is OK, one red it needs changing, two reds is desperately in need of changing.

The gadget seems quite well made and well thought out. I suspect the unit costing 15 times as much, with the curly linked probe tips, uses the very same electronics - just an op-amp comparators, precision resistors, lighting LED's. There is no means to adjust the calibration.

Dissolved copper, will be copper sulphate I think, which I believe is conductive in solution(?).

I am not aware of steel brake pipes being internally or externally copper plated.

I thought I read somewhere, that such a fluid test has now become part of the new MOT test?

There's no requirement to test it. Indeed, here at least, the tester is still not allowed to remove the cap on the brake fluid reservoir. There is now an EU-wide requirement to fail if brake fluid is contaminated. But the tester can fail if visual inspection shows it's clearly contaminated (eg a layer of screenwash on top?)

Yeah, same as mine, I was more interested in the levels themselves and their impact on a braking system ITRW.

Not seen those.

Check. I demonstrated it's 'sensitivity' to moisture by just wetting (licking) a thumb and laying the probes on it (shows 4 LEDS). The reading will change pretty quickly as you remove and release the probes from your thumb (as the moisture dries out).

Check.

That was my thought.

I was going from this:

"Myth #7 There are no copper parts in a brake system so there can?t be dissolved copper in the brake fluid?

The steel lines on a vehicles brake system start off as a flat piece of metal. It is then rolled into a hollow line and brazed with copper from the inside out making a seamless line. The copper alloy used to coat the inside of brake lines is where the copper content of brake fluid comes from. The brake fluid dissolves it from the interior of the brake lines and suspends it in the fluid."

It's the reason / justification for moisture levels being worthy of consideration that I'm still interested in. Eg, What level of say moisture (alone) in a brake fluid *would* actually be likely to stimulate corrosion to the vulnerable parts (cast iron master / slave cylinders and calipers) and over what period of exposure?

The gadgets would suggest >=2% but is that realistic and over what period?

I'm not asking you for answers, I'm just asking out loud. ;-)

The answer would go some way helping us understand the r/w risk and pertinence of the values as indication on these testers etc.

Cheers, T i m

T i m expressed precisely :

I have always assumed that the pipes were extruded, certainly I have never seen any evidence of any seams in the pipes, nor any weakness which might suggest any sort of seam.

Internal corrosion of brake pipes is less of a concern than internal corrosion of pipe work. Pipe work is much thinner than other parts and the major problem is usually external corrosion, though internal corrosion is obviously hidden from sight.

I was advised by my MOT inspector to grease my pipes, to help protect them - which is what I do on the most exposed sections. I clean them off, check them, oil soak them then finally paint on thick water proof grease. Some really exposed sections I have covered with that split car electrical trunking, over the top of the grease.

I did a fluid change around 3 years ago, the recommended is every 2 years, so at 1% - I'm happy to leave it for at least another year.

I would suggest corrosion will be almost none existent at 1%. The big concern is moisture boiling under heavy braking effort, rather than corrosion.