Mondeo Mk3 brake pipe replace (offside front)

Disclaimer: I am a complete amateur at this stuff. Please do your own research and use your own common sense. I'm not responsible for any damage you do to yourself or to your car. I'm just sharing my own experiences here for the hell of it :)

Two years ago I had an advisory on the MOT for “slight corrosion” of the offside front brake pipe. I’ve now found some time to look into it. I gave the pipe a good rub with wire wool and mostly it was just some protective paint/plastic which had flaked off where the pipe is exposed to the road but there was one bend where there was some actual metal corrosion and as this would not rub out with wire wool it seems that my advisory had now turned into a potential MOT fail. I really must stop ignoring these ‘advisory’ things !

Cars are generally manufactured with steel brake pipes because it is the cheapest material but, of course, these will eventually rust. When they are corroded badly enough they need to be replaced and are generally replaced with "Kunifer" pipe ( 90% copper / 10% Nickel ).

The offside front seems to be the easiest to access of all the brake pipes on a Mondeo so I thought I would try to DIY this one.

Here are all the tools I used...

Clockwise, from top:

• Flare nut spanners (avoid using ordinary spanners on brake unions as there is a risk of rounding off the fittings). You will need 11mm for male fitting and 13mm for female fitting. I also used the 16mm spanner for tightening/loosening the die on the pipe flaring tool
• Pipe flaring tool for 3/16” pipe. This is the more expensive kind of flare tool ( which can be used in situ ) and is very easy and accurate to use. You could use one of the cheaper vice mounted tools instead if you wanted.
• Pipe bending tool
• Pipe cutter – just a standard plumber’s pipe cutter that you would use on 15mm / 22mm household copper pipe
• Brake fluid – for lubricating the threads of the pipe unions and to top up the reservoir when you bleed the brakes after fitting the new pipe
• String – for measuring, against the existing pipe, how much length of Kunifer pipe you need to cut
• Stanley knife – poor man’s deburring tool, for deburring the cut pipe and putting an internal chamfer on it
• 10mm ring spanner – for tightening the jaws of the pipe flaring tool
• Felt tip pen – useful for marking the length of pipe to cut and marking points on the new pipe where bends will be made
• End caps – make these yourself as part of practicing how to use the flaring tool. If you make two male and female pairs then you can avoid any brake fluid spilling on your nice driveway etc
• Male and female brake pipe unions (10mm x 1mm). You’ll need three of each as a minimum if making the end caps but you may as well buy a whole bunch of them as they are so cheap.
• Kunifer pipe – 3/16" diameter. Sold in 25ft coils. Offside front pipe needs about 4ft of pipe. (Keep the rest for when your other pipes need replacing ! )
• Length of ½” PVC pipe – use this to straighten out the pipe as it comes off the coil
• File – for filing off the burr after cutting the pipe and for filing an external chamfer on the cut end of the pipe

I’d never made a brake pipe before so before removing the old pipe I did some practicing. There are plenty of Youtube videos covering the process. This one is quite good: https://www.youtube.com/watch?v=Qli4jSGoDTo

Straighten out some of the pipe by pulling it through the ½” PVC pipe as shown here: https://youtu.be/BHGPfA1xAjY (the pipe slides through easily if you keep the little plastic protective caps that should have come with it on)

Cut a short length of pipe from the coil with the plumber’s cutting tool. File off the protruding burr that the cutting tool leaves.

Continue 'internal deburring' and also make a small 45 degree internal chamfer in the pipe using the Stanley knife blade

Make a small 45 degree external chamfer on the pipe using the file.

Now the pipe end is ready for flaring….

Use the flare tool to make a male end (using OP1 of the tool’s die) and put a male union (small 11mm connector) behind it. Put the female union (large 13mm connector) on the pipe and then make the female end (using OP1 and then OP2 of the tool’s die). Remember to use the punch grease when making the flares.

Male end…

Female end (union/fitting is out of view)...

Connect the two ends together... doesn’t need to be excessively tight, but tight enough for the two ends to press together and form a sealed joint.

A brake pipe for a mountaineer... ?

Now cut the last two inches off of each end and turn them into end caps by hammering the pipe closed ( I also ran some solder along the hammered end for good measure ). I made up two sets of these...

Okay, enough practice! Let’s get the old pipe off the car...

Unbolt the engine bay end of the pipe (a plastic bag underneath the joint is a good idea to catch any brake fluid) then quickly place male and female end caps on to prevent losing all your brake fluid…

The pipe can now be released from two plastic clips at the back of the engine bay; these were quite stiff and had to be carefully prized open while pulling gently on the pipe. Be careful not to whack that nearby plastic brake vacuum pipe.

Jack up the offside front of the car and remove the road wheel. Please be safe! I use a trolley jack AND axle stands AND several sections of tree trunk all wedged under the car. You don’t actually need to get under the car for any of this but you do need the road wheel off in order to access and remove the pipe.

Remove the small piece of plastic cowling at the bottom of the wheel arch for easier access (2x 11mm bolts and 1x 8mm bolt)

Unbolt the male union from the flexible brake hose and fit the other pair of end caps…

The third, and final, clip holding the pipe in place is just out of sight behind the wheel arch. Have a look with a mirror...

I also found this one quite stiff, but you can see how it works... just prize the clip open while pulling gently on the pipe.

I found that the pipe could now be withdrawn through the wheel arch without needing to bend or cut it in any way. Great! That means we can use it as a template to fabricate the new pipe entirely outside of the car.

With the old pipe removed, take the end caps off and drain the fluid out of it.

Measure the old pipe length with the string and cut some Kunifer pipe to match that. Mine came to 121 cm, which included some extra for the flares and also a centimeter or two extra just for good measure ( I did end up removing a few centimeters though, later on, before making the second flare in the pipe).

When bending the new pipe be careful not to scratch or dent it or you may need to start again. That’s what happened with my first attempt… my pipe bender is a bit cheap and nasty and also I was trying to make every bend entirely with the bending tool. My second attempt was successful though and this was because I only used the bending tool to get the approximate shapes and then made final adjustments by hand.

I made the male end first (the bends at that end are more fiddly) and then worked towards the female end making all the bends. Compare the two pipes carefully for length and cut off any excess before making the female flare. Of course, it’s better to be a little too long than too short, as the bishop said to the actress, and I think my pipe was about 1 centimeter longer than the original.

Here is the finished pipe... Hooray!

Now fit the new pipe to the car... feed it in through the wheel arch, push it into the three clips and then connect up the wheel end of the pipe first followed by the engine bay end.

Finally bleed the brakes, top up the brake fluid reservoir, check very carefully for leaks and then test the brakes. I drove around some quiet, empty streets doing a few emergency stops and then checking for any leaks at each end of the pipe until I was satisfied that all was well.

I’ve checked the pipes on the other three corners of the car and I think I’ve caught those in time… I can only see some light bubbling of the protective coating on the parts of those pipes exposed to the road, so I’ve now coated those with some thinned grease (50/50 LM grease / unused engine oil applied with an old paint brush) to protect them from actual metal corrosion. 

Update: Okay, the car has just passed this year's MOT so my new pipe was good... but I now have corrosion advisories on the two rear brake lines so I'll see if I can address those properly a little bit later on this year...