Brake Fluid Tester temptation

[Pugglt Auld Jock]

Ok, last update until I have something worth reporting concerning my monitoring of the sample of brake fluid.

I thought about it for, oh at least, a few minutes and decided to pour a new sample of fluid from the same container I used earlier in this post. I decided to not simply continue with the sample I'd already tested because I noticed the boiling point tester caused the whole sample to warm up and, by it's very nature, the sample inside the end of the tester is raised to well above 100 dgrees C so must boil off some of the moisture - it is quite a small sample in that wee cup included with the tester.

I found a small glass container - which previously held some of Lidl's very best creme caramel - washed it out very thoroughly and dried it in the airing cupboard over night. Then dispensed at least twice the sample quantity into it than would have been possible with the tester cup. I've placed it on a shelf just inside the garage up and over door so it's in the draught of outside air which blows round the edges of the door but sheltered from the rain. I've left the top open so it can absorb moisture more rapidly than it would in a master cylinder reservoir as my main interest is in comparing the readings from the two testers rather than how long the fluid might take to become dangerously contaminated. Although it will be interesting to see how long this open container takes to get to that stage won't it?

Here it is, in all it's glory!



I'm intending to test it once a week but concerned that testing with the boiling point tester will alter the moisture content by boiling some of it off, which would prolong the test unnecessarily. So We already know that last Sunday 9/10/22 it tested at 243 degrees C and under 1% water with the resistive (Lidl) tester when I tested the sample in the wee container from the Liquid Levers tool kit I think it safe to say we can take this as the first reading. Today I've just tested it again but only with the Lidl tester and again it shows only one light - in addition to the battery ok light - so it's showing under 1% water again.

Because I don't want to reduce the moisture content and thus prolong the test, I'm going to test once weekly with the Lidl resistive tester until it lights up another light and at that point I'll test with the Liquid Levers boiling point tester to see what the corresponding boiling point is. I'm hoping eventually to be able to ascertain what boiling points correlate to the lights on the Lidl tester.

Going to be a long haul I think folks but I think the outcome may be interesting? I'll be back when the next light illuminates, don't hold your breath though!

 

[eeeno]

You might want to speed it up by adding 1% water and test and increase water and test. Brake liquid might not absorb moisture from air that fast, maybe it takes several weeks to even get to 1%.

 

[vexorg]

Or less fluid in the jar, that will give a bigger surface area to volume to speed up the relative level of water absorbed.

Or when misses isn't looking, hide a jar in the oven so it gets thermal cycled too

 

[Pugglt Auld Jock]

Or less fluid in the jar, that will give a bigger surface area to volume to speed up the relative level of water absorbed.

Or when misses isn't looking, hide a jar in the oven so it gets thermal cycled too

Had bigger and dirtier things than that in the oven, for instance dynamo/alternator end plates, small engine crankcase halves and even a hub assembly to expand it when fitting wheel bearings. Also put things like bearings and flanges in the freezer. We started going out together in our teens and she's grown up with me building motor bike engines on the kitchen table when we lived in the London flat and using the kitchen sink as a parts cleaner. As long as I cleaned up after she didn't seem to mind too much. Mind you, although I still use the oven and freezer, it's been years since I did anything like cleaning stuff in the sink as our second house had a garage as has all subsequent houses.

 

[theoneandonly]

How to stir memories.
2hrs to change main bearings from out of bike to putting chain back on. The longest time/ hardest bit was carrying the engine up 3 flights of stairs.

 

[Pugglt Auld Jock]

Well, I'm back here much sooner than I was expecting. I've been checking the little sample tub of brake fluid weekly since I decanted it back on Sunday 9th October. At that time it was showing the lowest reading on the Lidl resistive tester at less than 1% and the boiling point tester came in at 243 degrees C.

Tested again on the 14th Oct with the lidl tester only (reasons given above) and it came in at less than 1% again

Tested again today, 23 Oct and the resistive (lidl) tester lights up all it's lights - so more than 4% moisture which indicates that if the fluid was in a vehicle it should be changed immediately!

I was feeling very disappointed at that outcome because I thought there must be something wrong with the little Lidl tester. Oh well, it was pretty cheap, Hey ho. But lets try it with the Liquid Levers boiling point tester, just out of interest. Wow, maybe the Lidl tester does not "speak with forked tongue" (remember The Lone Ranger and Tonto?) because this comes up with 107 degrees C (114 first reading, 109 second and 107 third) - Remember DOT4 becomes "risky" when under about 170 and should be changed when it dips under 155. Maybe the Lidl tester is Ok?

Let's double check by dipping Becky's reservoir again. It comes up at less than 1% on the resistive tester and slightly down on the test result from a couple of weeks ago - which came up with 213 - at 210 degrees which is probably just "experimental, real world, error". So I think the result is valid but I'm very surprised that it's gained moisture so quickly just sitting, uncovered, on the shelf in my garage.

At this time I believe the test results do prove the resistive tester seems to give a reliable result but I'm going to repeat my test with a fresh sample of brake fluid and check it every second day rather than once a week. I'm hoping to get a more graduated result. Still can't quite get over how quickly this sample seems to have degraded. It's definitely not been contaminated with anything, just sat there, open to the air so it can absorb all the air born moisture it can. Seems to say to me that my obsession with not removing master cylinder caps unless you've absolutely got to is not such an obsession after all?

So, that was a bit of a surprise! I'll be back when I have some more finely graded results to report.

 

[portland_bill]

Hpefully the fluid in the 'opened but resealed' container will still give results similar to when originally opened.

Amazing how quickly it has absorbed moisture. We've had mostly damp days down here for the last week or so, has it been so with you?

 

[Pugglt Auld Jock]

Hpefully the fluid in the 'opened but resealed' container will still give results similar to when originally opened.

Amazing how quickly it has absorbed moisture. We've had mostly damp days down here for the last week or so, has it been so with you?

Way ahead of you there PB, That's going to be my first check. I've a few things to do today but I'm hoping to have time to get the next sample set up by tonight and getting initial, base, readings with both tools will be my first task.

I've been considering the positioning of the sample container. It's on the shelf below my precision tools cabinet, so protected from anything falling into it and about 3 ft off the floor next to the inside of the garage door so not subject to ground moisture or rain getting into it when I open the outer door. In terms of temperature and exposure to moisture it's probably not that dissimilar to a master cylinder under a closed bonnet, albeit with no cap on! Have to say I wasn't expecting this outcome. I thought it would take months at best before the moisture content dipped into the "area of concern" readings. I'll be back as soon as I get some more "interesting" results.

Just thought, for comparison purposes, wonder if I should have a "control" sample beside it? I have a couple more of the wee glass containers so i could place another identical sample next to this one but with a top on and see how it reads when I'm testing the open sample? Also going to test the open sample with the Lidl tester only until I get a drop in readings to the unacceptable region because I'm wondering if the heating of the fluid by the Liquid Levers tester is affecting anything (doubt it though) Of course I'll test a sample from the container with both tools to get an accurate starting reading but I'll not subject the samples to the hot coil machine until the Lidl tester starts to show degradation of the sample.

Isn't this interesting? By the way PB, yes we've had a lot of rain and general dampness up here too. The sun's shining now though and it's supposed to be a nice enough day so I'm going a walk up to the library now to return some books and then swing round by the Water of Leith walkway, just to see the water tumbling over the weir, on my way back home. So, watch this space, there's more exciting stuff to come soon!

 

[eeeno]

You could simulate the moisture content in the liquid to see how accurate the tester actually is. However the usability of these resistive testers is questionable at least. Brake liquid should be changed every five years at least to stay on the safe side. So if it's changed at every 3-5 years then who needs these testers. Even five years old liquid was fine for my chinese crap tester. It appears that the one from Lidl is good enough.

 

[Pugglt Auld Jock]

You could simulate the moisture content in the liquid to see how accurate the tester actually is. However the usability of these resistive testers is questionable at least. Brake liquid should be changed every five years at least to stay on the safe side. So if it's changed at every 3-5 years then who needs these testers. Even five years old liquid was fine for my chinese crap tester. It appears that the one from Lidl is good enough.

Yup, I agree. These testers are only for intermediate service time reassurance. I'm attracted to the idea of plotting definitive readings against know amounts of moisture (water) added but I'm very doubtful as to whether I could accurately administer a 1% dose? I'll be happy if I can just achieve a graph of the boiling point tester results against the resistive tester readings. At the end of the day though it's all pretty academic as I think it makes sense to renew the fluid regularly to reduce/prevent internal corrosion of components in the braking system. I do question though as to how many systems are properly bled through which would include driving the ABS pump and operating the valves? Not many would be my guess.

 

[s130]

Renew Brake Fluid - Absolutely - Add here is my problem!

Old/Older Age - Dodgy Back - No Vehicle Lift - 2nd Party Involvement

On my old Fiats, 600D, 127, Unos, Tipo I was younger and getting the car jacked up, wheels off etc. was a doddly.

With my Stilo Abarth, Croma 2005 and now my 500X my age and back are older, the wheels are wider and much heavier and hard back work to take off / put on only a couple inches above the ground. This process takes much longer the dear wife (2nd party) quite rightly gets bored with hanging around while you switch between front and back with all the jacking and wheel changes involved.

Having just barely recovered from a serious back problem (yet again) I need to get some service work done on my 500X but brake bleeding is going to have to go on hold. I normally change brake fluid every 2 years but will now push this to 3 years.

I have a pen tester but was never happy with it's accuracy and it gave a dodgy reading on an unopened brand new bottle of brake fluid.

Certainly the professional "boiling testers" are going to be that far more professional and accurate testing but they are not cheap!

 

[Pugglt Auld Jock]

Renew Brake Fluid - Absolutely - Add here is my problem!

Old/Older Age - Dodgy Back - No Vehicle Lift - 2nd Party Involvement

On my old Fiats, 600D, 127, Unos, Tipo I was younger and getting the car jacked up, wheels off etc. was a doddly.

With my Stilo Abarth, Croma 2005 and now my 500X my age and back are older, the wheels are wider and much heavier and hard back work to take off / put on only a couple inches above the ground. This process takes much longer the dear wife (2nd party) quite rightly gets bored with hanging around while you switch between front and back with all the jacking and wheel changes involved.

Having just barely recovered from a serious back problem (yet again) I need to get some service work done on my 500X but brake bleeding is going to have to go on hold. I normally change brake fluid every 2 years but will now push this to 3 years.

I have a pen tester but was never happy with it's accuracy and it gave a dodgy reading on an unopened brand new bottle of brake fluid.

Certainly the professional "boiling testers" are going to be that far more professional and accurate testing but they are not cheap!

I know exactly what you're talking about here. In my youth I remember lying under stuff like Cortinas, Marinas, and the like, up on stands or even with two wheels up on a very high curb and me lying in the gutter (particularly remember working under my Anglia like that) lifting down gearboxes with the bell housing balanced on my knees while I wrestled the tailshaft with my hands. It'd literally kill me now! I've noticed of late how much heavier modern wheels/tyres seem to be and I do sometimes have trouble lifting them onto the hub and keeping them there until I get that first nut/stud in. The Panda, with those wee projecting dowls is a great idea and I'm thinking of getting some of those removable aligning studs I've seen others on here talk about.

Regarding brake bleeding. Quite some years ago I bought the Gunson pressure bleeder and it worked quite well but of late I've had a couple of disasters with it leaking because the seals are old and don't seal very well. I tried to modify it to make it better but it's not been a success. I've been thinking of a suction bleeder because, by it's very nature, it can't "explosively" leak. I borrowed one to try it out and actually it worked quite well, but I don't like that it introduces air bubbles into the bleed pipe so you can't see when all the air is eliminated from the car's pipes. I've gone back to bleeding with half strokes - to save the m/cylinder seals - which is Ok in the summer as Mrs J is happy to assist but in the cold weather she just flat refuses! I can still get a major service done in a day but the repeated getting up and down does take it out of me and I'm wondering how much longer I can go on doing these larger jobs. I really need to do the rear axle on the Panda when the better weather comes back next spring - I'll remove it first and get it stripped down, just in case I find I can't manage it, and only then order the new one (from I M Axles I think - like the sound of the thicker spring pans they say they make them with) I rather suspect that, if I actually manage to do it, it may be my last "big" job on any of the family fleet and it really depresses me when I think of this.

 

[s130]

I know exactly what you're talking about here. In my youth I remember lying under stuff like Cortinas, Marinas, and the like, up on stands or even with two wheels up on a very high curb and me lying in the gutter (particularly remember working under my Anglia like that) lifting down gearboxes with the bell housing balanced on my knees while I wrestled the tailshaft with my hands. It'd literally kill me now! I've noticed of late how much heavier modern wheels/tyres seem to be and I do sometimes have trouble lifting them onto the hub and keeping them there until I get that first nut/stud in. The Panda, with those wee projecting dowls is a great idea and I'm thinking of getting some of those removable aligning studs I've seen others on here talk about.

Regarding brake bleeding. Quite some years ago I bought the Gunson pressure bleeder and it worked quite well but of late I've had a couple of disasters with it leaking because the seals are old and don't seal very well. I tried to modify it to make it better but it's not been a success. I've been thinking of a suction bleeder because, by it's very nature, it can't "explosively" leak. I borrowed one to try it out and actually it worked quite well, but I don't like that it introduces air bubbles into the bleed pipe so you can't see when all the air is eliminated from the car's pipes. I've gone back to bleeding with half strokes - to save the m/cylinder seals - which is Ok in the summer as Mrs J is happy to assist but in the cold weather she just flat refuses! I can still get a major service done in a day but the repeated getting up and down does take it out of me and I'm wondering how much longer I can go on doing these larger jobs. I really need to do the rear axle on the Panda when the better weather comes back next spring - I'll remove it first and get it stripped down, just in case I find I can't manage it, and only then order the new one (from I M Axles I think - like the sound of the thicker spring pans they say they make them with) I rather suspect that, if I actually manage to do it, it may be my last "big" job on any of the family fleet and it really depresses me when I think of this.

Sounds like you (and others) are in the same boat as me, but possibly a little further up/down the river.

When you have as many years of quality vehicle maintenance as we have, have seen what the cowboys and shoddy dealer technicians can do/damage, and you look at your pride and joy and then your pristine / well kept and stocked tool cabinet with all those specialist tools built up over the years, etc. then it *REALLY* hurts to know that at some point, not far round the corner, you are probably having to give it all up and just hope you can find a decent, honest and someone who cares as much as you do to take over where you left off!

Sadly I moved away from my "Fiat Knight In Shining Armour" (Dean at Small Car Services) so am currently on the hunt for another I can unreservedly trust.

 

[portland_bill]

Regarding brake bleeding. Quite some years ago I bought the Gunson pressure bleeder and it worked quite well but of late I've had a couple of disasters with it leaking because the seals are old and don't seal very well.

I've been thinking of a suction bleeder because, by it's very nature, it can't "explosively" leak. I borrowed one to try it out and actually it worked quite well, but I don't like that it introduces air bubbles into the bleed pipe so you can't see when all the air is eliminated from the car's pipes.

I've used the Gunson pressure bleeder on a few cars, and always made a mess. It fills the reservoir to the brim, so even if none leaks during bleeding, detaching the bleeder will be messy.
Only cars I found it useful for were the Marina and Dolomite clutches. Both have a pipe that arcs over teh bell housing, so air rises to the centre of the arc, and one full push on the pedal does not move the bubble as far as the bleed nipple.

I've had a cheap plastic vac pump for years. This works quite well, but as Jock says, it pulls air in past the bleed nipple threads, so you're never quite sure it is bled properly. I now will remove the nipple, and seal it with a couple of turns of PTFE plumbers tape. Working for me so far. Sadly, my partner now only has one leg, so cannot get her into the car to push the pedal. She's also very deaf, so could not hear the 'up', 'down' instructions, so I'm on my own.

 

[chris3234]

Renew Brake Fluid - Absolutely - Add here is my problem!

Old/Older Age - Dodgy Back - No Vehicle Lift - 2nd Party Involvement

On my old Fiats, 600D, 127, Unos, Tipo I was younger and getting the car jacked up, wheels off etc. was a doddly.

With my Stilo Abarth, Croma 2005 and now my 500X my age and back are older, the wheels are wider and much heavier and hard back work to take off / put on only a couple inches above the ground. This process takes much longer the dear wife (2nd party) quite rightly gets bored with hanging around while you switch between front and back with all the jacking and wheel changes involved.

Having just barely recovered from a serious back problem (yet again) I need to get some service work done on my 500X but brake bleeding is going to have to go on hold. I normally change brake fluid every 2 years but will now push this to 3 years.

I have a pen tester but was never happy with it's accuracy and it gave a dodgy reading on an unopened brand new bottle of brake fluid.

Certainly the professional "boiling testers" are going to be that far more professional and accurate testing but they are not cheap!

If you lucky and a little bit flexible you may find your bake to reach around and open the bleed nipples with you car in the floor I was able to do it when I changed the fluid in my tipo with no issues

Just tired the steering to full lock each way for the front

And the good access at the rear thanks to a reasonable ground clearance


Any way that reminds me I probably need to change my fluid again next near it's probably about 2 years now

 

[Pugglt Auld Jock]

Ok, finally got round to setting up my second attempt at comparing the Lidl and Liquid Levers fluid testers.

Decanted a fresh sample of fluid into the glass "cup". Filled it rather fuller this time, maybe about a third of what you'd find in a brake master cylinder reservoir. Tested with the Liquid Levers boiling point tester and came out with 235 degrees C. This compare with the 243 degrees result on my first test - see top of page - I'm not sure if the fluid in the container has degraded by this amount or if it's just "experimental error". The Lidl tester, unsurprisingly, showed just one light lit up indicating less than 1%. I'll be testing it each day with the Lidl tester until the next light - indicating 2% - illuminates when I'll test again with the boiling point tester. Then I'll test again when the Lidl tool shows 3% and again as soon as it indicates more than 4% which is the highest reading on the Lidl tool. The Lidl tool scale has an exclamation mark from about 2.5% but only has indicator lights at 1, 2, 3 and 4 % so it will be interesting to see what actual temperatures correspond to the Lidl tool's lights.

 

[Pugglt Auld Jock]

Oh dear, things haven't turned out quite how I'd have liked with this. As you all know I'd been intending to monitor this sample of brake fluid every day day with the Lidl tester until it lit up the next light in it's 4 light sequence and I was then going to test with the boiling point tester to cross reference.

Unfortunately the plan has failed. I tested on Monday with the Lidl tester and it lit only the first light thus indicating less than 1% water content. Then the youngest of our grandchildren fell ill, sickness, etc (usual childhood stuff) but he was really pretty miserable so we've been doing childminding, and the hour's journey morning and evening involved, so mum and dad can work. This means being up at around 6am and home for maybe 7pm. Yesterday he was very much better so we didn't need to attend today and anyway, mum's at home today.

So we're back to normal today, although feeling generally pretty knackered! but I haven't been checking the brake fluid sample. Went to check it just now and the lidl tool looks like a Christmas tree with all the lights lit! The boiling point tester confirms that the fluid is contaminated beyond use. I'm feeling a bit annoyed with myself and I really can't be bothered to start all over again.

Now sitting in the living room with a cup of Lidl's best instant cuppaccino, listening to question time on the radio and trying not to succumb to lighting up the gas fire. I'm thinking about what I can take from my brake fluid "shenanigans" and I think it's this:-

The boiling point tester obviously works well and can be trusted so i don't have a problem with it.

The lidl tester is still of unknown accuracy, but does seem to indicate when a fluid is safe as it only has the "less than 1%" light lit when the boiling point tester indicates fluid in good condition.

So, at this time, I'm going to keep the Lidl tester for use when time is short - as it's so quick and easy to use - and I need to just do a quick check. If it indicates with the first light only (apart from the green battery Ok/device on light) I'm confident I can trust the fluid is good. If it lights more than one light I'll be double checking with the boiling point tester and I'll default to using the boiling point tester when time is not pressing - like when doing an annual service etc.

As additional comment I'll add that I've been surprised at how quickly the fluid deteriorates if left in an open top container. I think the rate of deterioration in a master cylinder reservoir where the top had been left off would be slower because the surface area vs reservoir capacity would be considerably lower (more fluid and less surface area for moisture to be absorbed).

Although I've been aware of the fact that brake fluid absorbs moisture since my earliest days of "fiddling" with cars, and how dangerous this "hidden killer" can be, what this wee exercise has highlighted to me is how important it is to deny the fluid access to the open air so from now on I'll not be removing the top from any reservoir without good reason and not leaving it open to the air for any longer than necessary. I'll also be quickly replacing the top on a "top up" container of fluid rather than leaving it open perhaps say for the duration of a bleeding operation. One of the major changes I'm going to make is not to store part emptied containers of unused fluid for more than a couple of weeks or so, maybe to top up after a major brake job or fluid change - and even then only with the top tightly fitted. Other than that I'll be buying new fluid whenever I need some.

So, in conclusion, I'm pleased with my new purchase - the Lidl tester - and think it's going to be a handy addition to my toolbox. However It'll be the boiling point tester I'll be turning to when precise decisions need to be made and I don't think their use should encourage the 2/3 year fluid change period to be ignored as there's more to fluid condition than just it's moisture content

 

[s130]

As additional comment I'll add that I've been surprised at how quickly the fluid deteriorates if left in an open top container. I think the rate of deterioration in a master cylinder reservoir where the top had been left off would be slower because the surface area vs reservoir capacity would be considerably lower (more fluid and less surface area for moisture to be absorbed).

Well a couple of years ago I was going to change the fluid on two cars so bought (trade) 5 litres of fluid expecting that I might need 1.5 if the job went not according to plan. A good choice in one respect as I ended up needing more.

The bad point is compared to a 500m or 1l bottle the 5l has a large fluid surface area and a large volume of air and water vapour above it. Recipe for self-expiry / contamination.

Won't do that again. Small bottles OR wait for a very air dry summers day and decant the 5l into ten 500ml bottles.

 

[Pugglt Auld Jock]

Well a couple of years ago I was going to change the fluid on two cars so bought (trade) 5 litres of fluid expecting that I might need 1.5 if the job went not according to plan. A good choice in one respect as I ended up needing more.

The bad point is compared to a 500m or 1l bottle the 5l has a large fluid surface area and a large volume of air and water vapour above it. Recipe for self-expiry / contamination.

Won't do that again. Small bottles OR wait for a very air dry summers day and decant the 5l into ten 500ml bottles.

I've found you always, nearly always, need more than you thought.

My local factor has a large display/self service double sided shelf unit down the middle of the shop with lots of "consumables" on display. You just pick up what you need and take it to the counter. The brake fluid is all in one litre containers. I asked him about this and he said 90% gets sold in one litre packs. So, presumably, "the trade" buys it that way too? Would make a lot of sense?

 

[s130]

I've found you always, nearly always, need more than you thought.

My local factor has a large display/self service double sided shelf unit down the middle of the shop with lots of "consumables" on display. You just pick up what you need and take it to the counter. The brake fluid is all in one litre containers. I asked him about this and he said 90% gets sold in one litre packs. So, presumably, "the trade" buys it that way too? Would make a lot of sense?

Certainly for a small independent garage I doubt that they do that many brake fluid changes in a week. Even if they did "opening a new bottle" for them / us surely has to be 100% confirmation that what goes in is as good as it can be.

As for big dealers I suspect some/many???? put whatever they can find left over on the shelf in and tick the "brake fluid changed box"!