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A question on brake bleeding

  • #1
    Registered Users Posts: 460 ✭✭ BlakeS94

    Need to change the brake bleed screws on my car, never done this before. Is it as simple as remove and fit new ones or is there anything I need to know besides fluid loss and keeping master cylinder topped up? Should I bleed each caliper after changing the bleeder or wait till I have all 4 done and then bleed them all


  • I really wouldn't recommend you DIY this one. Not if you haven't or aren't familiar with brake systems. Any local garage will do that job safely and it ain't gonna chew the wallet too badly. Too many folks are perishing on the roads dude. Best to be safe...

  • Whats wrong with them that you need to change them? Are they leaking? Are the rubber caps still on them???

  • Or worse they are corroded and sheer off. I have never ever heard of changing them.

    Clamping flexy hoses with a brake clamp will stop fluid leaking out and can bleed it after.

    Some cars differ as you have not said what car is it.

  • Reason I want to change them is because they're completely rounded, a flare nut wrench isn't turning them, and the size down doesn't fit. So my plan is to break them loose with a vice grips and replace with brand new ones, there isn't any signs of rust so I don't think they'd snap off.

    It's a Ford mondeo mk4

  • What size spanner are you using? It's very often not a standard size.

    Never uses a 12 pointed spanner either, far more likely to round the nuts.

    One for a mechanic IMO, it just isn't worth me spending hours on something when a mechanic will lift the car, change the nuts and pressure bleed the system for an hours labour.

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  • If they were tight enough for the corners to be rounded off then there is a strong possibility that one or more of them will snap off - and you are then faced with a much bigger problem.

    You may not see any signs of rust but they can still be seized solid.

  • Sure if your not having problems with the brakes theres no need to touch them.If the day comes when there is a problem you can cross that bridge then.

  • They're an 11mm, and I tried using an 11mm flare nut wrench to no avail. I see your point, but I like to try do as much as i can and learn along the way, but if you think maybe it's best left to a mechanic I'll take your advice on board.

  • If I was to tackle it I'd spray some penetrating fluid every day for a few days leading up to it would that not help?

  • I tested the brake fluid in the master cylinder with a brake fluid tester and it showed all the red lights which recommends to replace immediately.

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  • I think if you do them one at a time you will not need to bleed at all. Just break the bleeder before you remove brake hose, you may need a small grips. you should easily be able to remove, replace and tighten before master MT.

    If you put some cling-film over the master and replace cap it will reduce the flow to almost zero... you will need to put a tray under to catch what leaks and top up master after each wheel...

    Personally i would leave it "if its not broke don't fix it"

  • I have found that the penetrating oil does not seem to be able to reach where it is needed - and just under the part where the spanner fits the shell is quite thin and can snap easily.

    If it snaps and then you have to replace caliper most likely - and car off the road in the meantime possibly.

  • What i have done a few times in the past is saturate a piece of cotton sheet in WD and wrap around whatever and leave overnight, also spray more oil on the rag...

  • Just remember, these are very easy to brake. These days the well supplied garages may have a specialty tool for that purpose - vibro impact. It makes only little torque, but vibrate like a crazy.

  • Easy job and in theory should only need a very basic bleed as little air should be introduced.... That is until you snap one of the bleed screws. Then its a nightmare job.

    If you are using a vicegrip, be very careful. You will easily snap them with that but using with care, it will do the job. If small force doesn't do the job. Leave it.

  • I think I'll give it to a garage to do. I don't want to cause unnessary stress and mess up callipers, thanks for all the info guys much appreciated

  • Keep us updated. I think it is right thing to do. Only cover your back and make a price agreement. If they took that job, you do not care how many hours it takes and you pay only fixed price. Every single garage knows there is the risk. Once it took 5+ hours to get fixed by other mechanic. I really do not know why it took so long. He not only used his work hours, waste others work hours too. My strategy is to use reverse drill bits because sometimes it can crack it loose. Extractor tools typically is garbage