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Basic NCT Failure: Corrosion on brake pipes.

Red ford fiesta on ramp rkm

No one in the trade likes changing brake pipes.

james fitting the new brake pipesYou have to work in the dirtiest rustiest parts of the car.

  • Clips brake, pipe ends round, seize and strip.
  • Brake fluid leaks down your sleeve and all the time you are hoping the bleed screws slacken
  • And the master cylinder seals aren’t perished.

So based on my knowledge in the trade, here are my hints and tips on how to make the job easier.

  1.  Preparation: Soak every brake pipe end; and bleed screw you are likely to need to remove, with WD40 or similar.
  2. Give the releasing/penetrating oil a good 15-30 minutes to soak in.

For stubborn ends or bleed screws, slowly pour boiling water over them heating them with a gas burner risks melting seals in the wheel cylinders, callipers and plastic clips, but boiling water poured slowly over it usually does the trick.

Most replacement brake pipes are made of copper nickel alloy! but just make sure that it is proper brake piping, we only use high quality brake pipe-in Why take a chance just to lower the cost of a repair by a few Euro’s.

Cut the rot out!

fiesta old brake corroded pipe
This is the pipe that is corroded and caused this Ford Fiesta to fail the NCT test

don’t take chances  with brake pipes, cut the pipe with a decent pair of side cutters and get a tight fitting socket onto the end. You are going to be replacing the pipe anyway so why preserve it?

If you are removing a pipe that you will need to refit then use a brake pipe/flare nut spanner. Most cars have metric fittings nowadays but if you end up having to do this job a lot it might be worth kitting yourself out with a set of AF spanners too. As they are all slightly larger/smaller than the metric ones it comes in handy if you are removing stubborn or heavily corroded brake pipe ends

Insulating tape.

If you are fitting a new brake pipe over the top of a petrol tank or along the engine bulkhead behind everything there is nothing more annoying than getting the pipe in position only to find the end has slid back down the pipe! Sticking a bit of insulating tape or similar is enough to hold the end in the right position.

If you have to thread the pipe into an awkward place or behind loads of stuff take some single core wire to the old pipe and pull it through. When you have to fit the new pipe tape the wire to it, pull it back through and it will position the pipe as it should be. Easy!

Shaping the pipe.

fitting the new brake pipes fiestaI have watched people shape the new brake pipe then try to fit it. Why? with the exception of tight radius bends you do not need to do this as you end up bending the thing as you fit it.

Uniform bends can be made by bending the pipe round a socket etc. I have never seen the need to buy one of those pipe bender things!

Secure mounting.

Copper hardens with movement so make sure your brake pipes are securely mounted or they will break.

Make sure they will not rub against anything as copper is quite soft and wears fast. If you cannot avoid it slide some windscreen washer pipe over it to stop it wearing. If you break the small plastic mounting clips (which is easy to do!) replace them by cable tying it to something substantial. Never mount brake pipes on exhausts, steering components or brake pedal rods. It sounds obvious but be very mindful when working on brakes.

What the NCT are checking for

Brake pipes and the NCT: Contrary to what certain fast fit centres and car dealers will tell you, surface rust on a brake pipe is not necessarily a failure!

Common reasons for rejection.

Brake pipe excessively chafed, pitted, corroded or damaged.

  • Brake fluid leaking.
  • Poorly repaired brake lines / pipes.
  • Leaks around the callipers/wheel cylinders.
  • Damp areas around the brake drums.

Note: Chafing corrosion of, or damage to a rigid brake pipe so that its wall thickness is reduced by 1/3 (eg approximately 0.25mm for a typical hydraulic brake pipe) is a reason for rejection.

Put simply if the brake pipe is visibly thinner or pitted to the extent that it may burst open whilst driving! then it’s a fail.

Surface corrosion, slight chafing or flaking paint on first impressions may look bad but the tester is allowed to remove loose rust or paint with the ‘corrosion assessment tool spade end’ and at his discretion may decide whether the pipe has rotted to the extent that it may burst.

Other ways your rigid brake pipes can fail the NCT

If the pipe or ends are leaking (obviously!) if the pipe is inadequately supported or mounted (hanging off) or inadequately repaired (like cutting a burst bit of rigid pipe out and putting a piece of rubber hose in instead (that happens!)

What you can do.

You can however cut the corroded part of a rigid brake pipe, flare the end and make a small pipe up to replace the corroded bit as long as proper brake pipe ends and pipe are used and it does not leak etc.


If you need any advice on your brakes or you would like to booked your car in for a brake test, just give me a call Ronan

at Ronan Kelly Motors


Ronan Kelly Motors

Location : Greenhills Road
Walkinstown Dublin 12
Telp : (01) 4059077 / (086) 7341777
Email :
Open Hour :Monday to Friday
Saturday By Appointment Only

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