Repair to steel brake line

[scottyp123]

Had a look at my friends car the other day, brake level light came on shortly after he had to do an emergency stop. firstly I told him on the day to go and get some more fluid and top it up before it empties the ABS module - he didn't. It was a good few days after until I could have a look and it turned out to be the actual metal brake line going to one of the back wheels that is leaking and not one of the caliper seals as I thought it would be.

The car is a merc W204 2008, I take it the line is one piece all the way from the front to the back? Is it easier to cut the damaged bit out and put a piece in with some couplers, its years since I did any flaring on brake lines and would have to buy the tool to do it. Amazon do sell a kit which has a length of pipe and some couplers but I'm struggling to see how a male and female coupler work, do the two flared ends of the pipe meet up inside the coupler? and how hard will it be to flare the steel part of the pipe still on the car.

https://www.amazon.co.uk/AnvFlik-32-8Ft-Automotive...

[NMNeil]

Why is the brake line leaking? I'm assuming it's rusted which would mean the rest of the brake line will follow suit very quickly.
If you do a shortcut repair on the engine the worst that will happen is the engine will stop. Using the same shortcut repair with the brakes; people could die.

[steveo3002]

you would make a male flare on the 2 ends you wish to join , then screw those into a female joiner

like this

https://www.ebay.co.uk/itm/Brake-Pipe-2-Qty-2-Way-...

be aware the budget dregs flare tools struggle to flare steel pipe

[scottyp123]

NMNeil said:

Why is the brake line leaking? I'm assuming it's rusted which would mean the rest of the brake line will follow suit very quickly.
If you do a shortcut repair on the engine the worst that will happen is the engine will stop. Using the same shortcut repair with the brakes; people could die.

Most of the line is covered by various plastic covers and still looks like new, it is damaged where it drops down and is exposed near the rear axle. I was going to replace the piece of the line from where its behind the rear wheel liner to the caliper.

[scottyp123]

steveo3002 said:

you would make a male flare on the 2 ends you wish to join , then screw those into a female joiner

like this

https://www.ebay.co.uk/itm/Brake-Pipe-2-Qty-2-Way-...

be aware the budget dregs flare tools struggle to flare steel pipe

Thats what I thought you would get with the kit I linked to but it looked different, but looking closer at the picture the female coupler might be a back to back one but its only 7mm long, the pictures aren't very clear.

[LimSlip]

scottyp123 said:

Thats what I thought you would get with the kit I linked to but it looked different, but looking closer at the picture the female coupler might be a back to back one but its only 7mm long, the pictures aren't very clear.

The kit you linked to has only male and female ends, no couplers.

[guards red]

As has been said, your first issue will be trying to flare the current steel lines if you chose to cut and splice in a piece. They are hard as nails. You can flare them witha professional tool in a vice but that kind of defeats the object.

I would suggest as a minimum you'll need a hydraulic hand held flaring tool. These can be had, but they're not cheap.

Chances are that the orginal line is one piece from the ABS unit to the back of the car. You may be able to buy that pipe from Mercedes, but, whilist it will be the right lengh, it will be up to you to shape it. This is possible with the car on a full height lift and after removing various shields etc, maybe the fuel tank, it will probably not be possible on axle stands.

You, may need to replace it with cupro nickel pipe which is significantly more maleable and far easier to flare. Lasts way longer too.

[Stegel]

I’ve done the same job on an 09 E class, by the sound of it in a similar position. The pipe rotted through where it ducks out of a plastic arch liner, and everything from the liner to the front of the car is sound. The hardest part is indeed flaring the steel pipe - I used a Sykes Pickavent hand held tool which had no trouble, it’s quite pricey but cheaper kit will struggle. I used Kunifer pipe for the new section, and obtained some brass connectors from Automec. 4 or 5 years on all is still fine.

[scottyp123]

What about the compression type of couplers, are they safe. I've watched a youtube video where some redneck reckons they are fine after trying to pull one apart with his truck.

[Stegel]

scottyp123 said:

What about the compression type of couplers, are they safe. I've watched a youtube video where some redneck reckons they are fine after trying to pull one apart with his truck.

I too have seen them recommended but while I’ve used them on fuel pipes I wouldn’t feel comfortable using them on brake lines. Flaring pipe etc. means you are using the same principles in the repair as the original lines and fittings. I don’t know of any manufacturers that use compression fittings on brake lines, another vote against for me.

[steveo3002]

dont think the compression joints are favoured here in the uk ...not something you want to bodge up

[LimSlip]

scottyp123 said:

What about the compression type of couplers, are they safe. I've watched a youtube video where some redneck reckons they are fine after trying to pull one apart with his truck.

They are neither safe nor legal to use. The cretinous old duffer known as Scotty Kilmer actually shows how to repair a brake line using these in one of his videos, despite the packet being clearly marked as not suitable for brake lines!

[Arnie Cunningham]

I’ve flared a steel line before. It’s ok. Doesn’t need to go in a vice as long as you have a decent tool.

However, if my mate was the sort to keep driving after the brake light came on and ignored advice to at least top it up, I wouldn’t be doing a temporary fix.

Brakes are the one thing you really must keep in good order

[scottyp123]

Arnie Cunningham said:

I’ve flared a steel line before. It’s ok. Doesn’t need to go in a vice as long as you have a decent tool.

However, if my mate was the sort to keep driving after the brake light came on and ignored advice to at least top it up, I wouldn’t be doing a temporary fix.

Brakes are the one thing you really must keep in good order

I was thinking of warming up the steel line first before flaring it but I actually have no idea if brake fluid is flammable or not. Its been parked up on his drive since the line split, I don't think the brakes work for a second time after you rupture the line anyway. I was more concerned with him topping it up so the fluid doesn't drain out of the ABS module, I believe they are a right pain to bleed back up.

[rustednut]

scottyp123 said:

I was thinking of warming up the steel line first before flaring it but I actually have no idea if brake fluid is flammable or not. Its been parked up on his drive since the line split, I don't think the brakes work for a second time after you rupture the line anyway. I was more concerned with him topping it up so the fluid doesn't drain out of the ABS module, I believe they are a right pain to bleed back up.

Brake fluid is highly flammable!

With the best of intentions. It appears you are not well informed on brake pipes, joints and flares.

I doubt very much you will have, or have access to, any flaring tool that will flare steel on the car, let alone know properly how to join pipes (joiners are essential, not just a male/female joint) and would probably not recognise a good flared pipe from a bad 1.

Please get the car to a recognised garage. A brake pipe and bleed is not that expensive. Definitely cheaper than buying the tool and still getting it wrong.

[scottyp123]

rustednut said:

scottyp123 said:

I was thinking of warming up the steel line first before flaring it but I actually have no idea if brake fluid is flammable or not. Its been parked up on his drive since the line split, I don't think the brakes work for a second time after you rupture the line anyway. I was more concerned with him topping it up so the fluid doesn't drain out of the ABS module, I believe they are a right pain to bleed back up.

Brake fluid is highly flammable!

With the best of intentions. It appears you are not well informed on brake pipes, joints and flares.

I doubt very much you will have, or have access to, any flaring tool that will flare steel on the car, let alone know properly how to join pipes (joiners are essential, not just a male/female joint) and would probably not recognise a good flared pipe from a bad 1.

Please get the car to a recognised garage. A brake pipe and bleed is not that expensive. Definitely cheaper than buying the tool and still getting it wrong.

You are correct, I have done them before but it must be 20 odd years ago, I have done many many things on vehicles though including engines and boxes out, gearbox strip downs/repairs, I replaced the AC condenser on our van and gassed it myself and also replaced a bearing inside the front differential on my A4 with a sandwich toaster and an oven recently.

I can do anything mechanical if I put my mind to it and I don't think repairing a brake pipe would be out of my league, its just a matter of having the right tools to do it with and you make it sound like a specialist only job, if I listened to people who said "specialist only" I would never attempt anything.

[VanDiesel99]

I concur with the general theme of this thread. Leave it well alone. It could easily cost you your friendship and a lot more besides. Tell your friend to take it to a professional or a scrapyard.

[rustednut]

scottyp123 said:

You are correct, I have done them before but it must be 20 odd years ago, I have done many many things on vehicles though including engines and boxes out, gearbox strip downs/repairs, I replaced the AC condenser on our van and gassed it myself and also replaced a bearing inside the front differential on my A4 with a sandwich toaster and an oven recently.

I can do anything mechanical if I put my mind to it and I don't think repairing a brake pipe would be out of my league, its just a matter of having the right tools to do it with and you make it sound like a specialist only job, if I listened to people who said "specialist only" I would never attempt anything.

it is not a specialist only job.

But it is a very safety critical job, and requires a good level of experience and knowledge. This is not the type of work to just dive in and attempt.

Ask yourself, can you recognise a good flare from a bad flare? Do you have the tools required, or are able to access to do the job to the correct standard? Is it worth the expense of the tooling to do 1 pipe? What if the pipe/joint fails in use and causes damage, or even worse death?

How much is it to have it repaired professionally ?

[scottyp123]

rustednut said:

it is not a specialist only job.

But it is a very safety critical job, and requires a good level of experience and knowledge. This is not the type of work to just dive in and attempt.

Ask yourself, can you recognise a good flare from a bad flare? Do you have the tools required, or are able to access to do the job to the correct standard? Is it worth the expense of the tooling to do 1 pipe? What if the pipe/joint fails in use and causes damage, or even worse death?

How much is it to have it repaired professionally ?

Can I recognise a good flare - I can probably spot if its not turned out right and a badly made flare will leak where as a good one won't.

do I have the tools - not yet, I find its always better to spend the money on the tool to do the job instead of giving it someone else to do the job for you.

What if the pipe fails - Well its already failed and didn't cause any damage or death, are brakes not dual circuit anyway, will the light not come on if the fluid gets low but with plenty still left to stop the car.

How much to get it done - probably a small fortune knowing garages, that's why I always do my own repairs no matter how hard they are to do. It will also cost a similar small fortune to get the car to a garage now that all the fluid has leaked away.

[GreenV8S]

I think you're being unduly pessimistic. Replacing brake lines is a routine task and not likely to be particularly expensive. Getting disabled cars recovered locally for work is also routine and not particularly expensive.