Brake fluid contamination?

[veryverydarkblue]

What’s the chance or likely cause of brake fluid contamination within 12 months of the last change?

Dropped my Z into a premium local Indy garage today for it’s MOT and an annual oil change. Despite the brake fluid being done 12 months ago by Ross, and no doubt also looked at when I had all the discs and pads done 3 months ago, I was surprised to be called up to say it’d fail it’s MOT without a brake fluid change, that they’d already started on this, and it would be an extra £70.

I’m trying to work out whether I should be more concerned about the car (brake lines etc.), or the garages (this one, or the one which did the brakes), right now. Needing a change after 12 months doesn’t seem quite right… Any thoughts or similar experiences?

[plenty]

Does seem odd. What's their basis for diagnosing a fluid change? Is the fluid visibly discoloured? Have you told them the fluid was changed 12 months ago, and if so any reason given for needing to change it again so soon?

'We've already started on this' is a red flag unless you've explicitly given them an instruction up front to do whatever's needed. No garage should undertake chargeable work without prior approval.

[Chippie]

I think they’ve just pulled your pants down and are expecting you to bend over whilst they stick one up you, there’s no reason to fail a MOT because there’s no record of the brake fluid being changed, they test the braking efficiency on the rollers not the condition of the fluid.

[Special Kay]

From my uneducated understanding, the braking system is a sealed unit, the only 'contaminants' to enter your system would be via a leak or through pourous rubber hoses. It's quite plausible that your lines could've developed a leak or found a weak point (usually a bend or joint). But, you haven't mentioned any loss of braking in your post so I presume your brakes worked fine and still do. Your case sounds very fishy to say the least, I agree with you, the mechanics should've notified or brought this matter to your attention when the brakes were being worked on, on two separate occasions. Personally, I would take my car to another reputable indy garage to give your brakes a thorough check. I'm not familiar with what rules and parameters mot testers look for on brakes as I'm in the 90% category of people who wait in the room and get told it's passed or failed. But I would say, a brake fluid change after discs and pads changed is a little excessive given that it probably only needs a top up if anything.

[veryverydarkblue]

Does seem odd. What's their basis for diagnosing a fluid change? Is the fluid visibly discoloured? Have you told them the fluid was changed 12 months ago, and if so any reason given for needing to change it again so soon?

'We've already started on this' is a red flag unless you've explicitly given them an instruction up front to do whatever's needed. No garage should undertake chargeable work without prior approval.

Yes, they claimed that it was discoloured, although that was obviously unverifiable by me - I’ll certainly check it in advance next year. They didn’t have have the service history available to see, however I told them that it was done 12m ago on the phone after the fact. I’ll certainly press them further for likely causes.

The conspiracy theorist in me says they’re getting me back for not using them for the brakes earlier in the year - their quote to fit them was ridiculous.

Agree that they shouldn’t have progressed without authorisation, although I’m loathed to have an unnecessary fight with my only convenient garage. Too late to dispute the necessity, however if it really did need doing that soon, I’d like the know the cause

[veryverydarkblue]

Thanks all. By going ahead they’ve left me in a frustrating position that I can’t determine between the following potential situations

1) Something got unnecessarily disturbed during the disc and pad change - e.g. excessive backflow into the reservoir, bad top up fluid, cracked reservoir, cap not replaced fully
2) Something has degraded in the braking system in the last 3 months contaminating the fluid (However, brakes are solid as a rock and seems unlikely it would be visible in the reservoir as I’d expect expects fluid to only go in)
3) The prior brake fluid service wasn’t done (I trust Ross @ RBM, so would have been a mistake as other work done at the same time)
4) I’m being taken for a ride

Votes please!

[plenty]

IMO unless a reasonable explanation is given, or unless you already have an agreement that they are at liberty to go ahead without pre-authorisation, I'd be looking for another garage for future work. Unless you're talking about S54 valve clearances or similar, these are straightforward cars to work on and any competent mechanic could handle 99% of the jobs.

[veryverydarkblue]

IMO unless a reasonable explanation is given, or unless you already have an agreement that they are at liberty to go ahead without pre-authorisation, I'd be looking for another garage for future work. Unless you're talking about S54 valve clearances or similar, these are straightforward cars to work on and any competent mechanic could handle 99% of the jobs.

Agree. It’s only been their proximity that keeps me going back so far (For MOTs and Black Circle fitments). They’re not BMW specialists, but plenty of people seem to trust them with modern classics like Porsches.

Going by the MOT guidelines on brake fluid contamination checks, it would have to be pretty manky to fail via an external check through the relatively opaque plastic reservoir (caps should not be removed). It’s getting hard not to conclude that they felt like they were owed more of my preventative maintenance budget!

[Zedebee]

I think they’ve just pulled your pants down and are expecting you to bend over whilst they stick one up you

This.

[smorris_12]

Awooga! Awooga!

That's the taken for a ride siren going. The worst brake fluid I have ever seen was simply very, very dark through age (and was still passing MoTs!) Actual contamination in a sealed, non-circulating system is almost impossible. Tipping oil or jam into the reservoir is about the only way it's going to happen. Almost any sort of breach that would let something in is going to let brake fluid out at a far faster rate.

Threaten them with the man from VOSA who does the MoT monitoring.

[Mike6]

For an MOT it would simply be an examination of brake lines and check for leakage then braking performance. They just wouldnt have time within the MOT charge rates to start looking at colour of fluid in the reservoir.
They are conning you and most probably havent even changed the fluid. Go elsewhere in future.

[Smartbear]

I didn’t think the colour of your brake fluid was an mot failure, they wouldn’t be seeing my car again & I'd also like them to point out where the mot test stipulates about the colour?
I’d report them for it
Rob

[MikeyH]

I'm no expert but I have NEVER been failed for old brake fluid on any car, leaking hose, yes. Dodgy?

[veryverydarkblue]

The MOT check for brake fluid would only be a visual external check of the reservoir. As such it would have to be really 'off' to trigger a fail.

TBH, if they'd called me up and said it had failed for brake fluid, I'd have asked to see a photo for my reference and then let them go ahead. The whole proceeding without authorisation is the kicker here, as the evidence is gone before any chance to challenge the fix/ appeal the fail.

Anyway, on pick-up I was issued both fail and retest certificates that I wasn't expecting based on the original conversation. I probed hard on the causes of contamination and the boss seemed very keen to blame to previous fluid change being only half done at best, and that the car was otherwise perfect (noting all the shiny suspension and brakes they weren't involved in fitting). The fail certificate, issued by his garage, was given as the evidence the fluid definitely must have been bad.

This MOT fail point seems almost unique in that the fix is always 'in stock', the evidence will be gone, and it's easy money with the correct equipment.

Needless to say, I won't be going back again. If it was unnecessary I'm almost more annoyed by the impact on the MOT history than the money.

[Mr Tidy]

Needless to say, I won't be going back again. If it was unnecessary I'm almost more annoyed by the impact on the MOT history than the money.

I don't blame you!

I had several MOTs done at a local garage some years ago and they wanted to give my car an advisory for a low engine oil level, until I pointed out it had a low-level warning light that wasn't illuminated. Still got advisories for indicator lights not being very orange, two slightly deteriorated front brake pipes and uneven pad wear on the front.

Then I discovered a mate knew the owner of the MOT place the other side of the road so I've been using them ever since.