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Rust in brake reservoir

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by коннор, Feb 3, 2014.

  1. Today I replaced the fluid in the front brakes of my VFR. No problems with the actual job... but I discovered what appears to be rust in the the reservoir. I'm sure this is a bad thing, but I'm happy to admit my ignorance as to exactly how bad, or what it may indicate (aside from the fluid needing a change :p).

    I scrubbed it out as best I could with an old toothbrush and continued with my reverse bleed. Is that enough to be getting on with, should I cleanse it in some other way, or is there something I may need to inspect/repair/replace?

    I've yet to give it a test ride -that'll probably happen tomorrow- so I can't say if there are any apparent issues remaining (prior to the change braking power was... unsatisfying).

    Pics because it did happen:

  2. How olds the bike? When was the last time the fluid was changed?

    Me personally I'd reco the whole system, isn't going to cost much and if your bleeding your own brakes DIY shouldn't be an issue.
  3. With a reverse bleed you just pushed all that crap from near the calipers all through the rest of the clean lines and master cylinder and into the reservoir.

    there is a reason you push all the crap down and out the bleed valve at the calipers - cause that is where all the water absorbing and heat cycled fluid is in the first place.

    all the rust is from the water absorbed into the calipers and lower lines.
    It would be best to replace those lines and get a caliper rebuild kit to reseal the pistons.
  4. It's an '89 750F. To be honest, the fluid hasn't been changed in the couple of years I've had it, and I do not know when it was last done before that.

    This is the first time I've (personally) changed brake fluid on any bike, but I would be up for pulling stuff apart and learning new things.

    I think I'll be adding something to the list of stuff to do as soon as a bring a second hand bike home :p. Might go so far as to eyeball it when inspecting bikes, too.

    To be clear, those pictures are both from before I did anything more than sop up the fluid that was in the reservoir. I do not recall seeing any rust in the fluid that was pushed up.
  5. Gigitt is spot on, as a brake mechanic I can tell you brake fluid absorbs moisture that will build up as residues in the base of calipers and master cylinders, NEVER reverse bleed as master cylinder cups and seals ( which only work one way )also have residue behind them including residue due to the result of wearing bores, last thing you want to do is to try and push past them with new fluid.
  6. Never?

    What about with a completely new system? I usually do this to get lever pressure straight away, then do a normal bleed. Surely that couldn't do any damage?
  7. I was aware of that -- it's the main reason one should replace the fluid regularly, as the water lowers the boiling point (and brakes don't work so well when that stuff is boiling). Given the large amount of rust in the reservoir, I don't think it was pooling at the bottom, or at least it had worked its way in from the top before heading down.

    As I understand it, there is some movement of fluid between the reservoir and the rest of the system, so I expect some measure of rust would have worked its way at least into the master cylinder.

    So I would probably want to strip and check it even if I had down-bled it.

    How, exactly, do they work only one way without locking the brakes on? Serious question, as I can't think how it would, and you're obviously in a position to know and therefore explain.

    I have been looking for more information on how reverse bleeding damages things, and so far have only found people warning against doing it on ABS brakes. On the other sdie of things, I have found this post on another forum (and last night saw someone saying much the same somewhere else), and there is an American company (and we all know how they fear lawsuit over there) which makes a tool explicitly for reverse bleeding, though I expect they've designed it to push at a specific level of pressure.

    In my internet travels I came across someone saying that it is the standard practice in factories, though that was some bloke on some forum that I can't even remember now :p.
  8. Had a looksee in the clutch reservoir (woulda sooner, but one of the screws was being special). Seems it's about the same as the brake one was.
  9. Gaffa tape bro, fixes everything
  10. So, uh, here are some snaps of the *clutch* reservoir:


    I'm pretty sure that stuff made my jar of paint stripper darker when I dumped it in. But wait, there's more!


    The stuff on the left hand side was gunky. I gave it a little bit of a scrub out and chucked fresh fluid in there (haven't flushed the line) for the moment in hopes that'll work in my favour when I come back to it.

    Any tips on getting the all rust out? And, of course, what does this foreshadow?
  11. that stuff looks nasty... looks like choc syrup!

    is that what brake fluid looks like when it breaks down?
  12. I wouldn't be surprised. All I can say is that the clutch was still working okay :shrug:.

    Is there anything that would act as a cleaner without screwing things up? I'm thinking replacing a whole load of seals will probably be in order in any case, but I'm not familiar with the insides or all the potions available, and there's always the possibility that stuff has survived surprisingly well.
  13. Rust ? Are you a goose ? What metal is your shit made from ?
  14. That fluid looks like it's been in there since the bike left the factory in 89.:LOL:
    If you value your life, overhaul the entire brake system. The clutch is not so life threatening, so you'd get away with just changing the fluid. But to clean it properly I'd recommend a complete strip & overhaul. Any cleaner strong enough to get rid of all those stains is going to destroy your seals.
  15. An iron alloy, duuuuh ;).

    Yeah, I've been meaning to strip, clean, and inspect since I discovered the problem. Today I got a start on it, and have some good news (for myself :p):

    After my earlier scrub and subsequent soak in fresh fluid, the reservoir only had a thin layer that came off easily with some CLR. Most importantly, the MC bore looks like it's fine, so simply rebuilding it should be fine. The rust appears to have been centred around the banjo bolt.

    I suppose the bad news is that the last point there suggests the source of the rustiness may lie further down.

    The callipers are next on the agenda, though I may not get them done today.

    brakebetter. brakenow.
    (Couldn't get a good shot of much else)