W123 300D Hard Brake Line
 

Hi all, I've tried searching but am confused with some of the answers on it. On my 85 300D, my brake line is leaking somewhere above the rear driver wheel and it looks like it is corroded badly. What is the best method to replace the line from the master cylinder and where's the best place to get the lines? Dealer is the only option?

Dealer is an option but the line just comes in the correct length - not pre-bent

A cheaper option is to make your own though you need to get a BUBBLE flare flare tool (and ideally a bending tool so you get a clean even bend - not compressed / squashed)

I would expect a decent olde worlde garage would make up a line for you too.

double flare? are you sure you don't mean BUBBLE flare?

Sorry yes - ISO bubble not double - temporary blip in the transmission...

To make amends (!)

How to Make Your Own Perfect Bubble Flared Brake Lines Every Time | Eastwood Blog

Check out this link below for pictures of how it's set up back there. The line from the rear driver wheel goes to a T junction. Same with the line from the rear passenger. There is only one line coming back from the master cylinder - this junction serves to split the fluid between the rear calipers.

With any luck, you'll only need to replace the line from the rear driver wheel to the junction. It's a short run of line, if so.

Mercedes W123 Brake Line, Rear Replacement - iFixit

All self standing auto parts stores sell pre made lines in many lengths. My guess is you have not done much brake system work over the years. This pre made line can do the job if about the needed length.

If not you have to have flaring tools and buy a roll of brake line. The pre made lines are cheap. They are just straight lengths so you will need to have a tube bender or borrow or buy one though. The flares and coupling fittings are already on the pre made length.

Your only issue will be to make sure you pick a line with the right size terminatons on it. That is not rocket science. Take your old one in with you. There are only two common metric sizes I think in common use as brake line fastenings'.

Just to confirm, the premade lines would already have the fittings installed in them? I don't have the tools and not very knowledgeable in putting these fittings. So with the approximate length and correct fitting, it should bolt right on? What mm is the fitting?

I've read that no matter where you buy it, dealer or auto part store (autozone), I'll need a bender for it? Is this true?

Would the t junction need to be replaced?

Thanks for all your help!

x2 bring the old one in with you (or buy both and return one)

You can bend them by hand, just don't kink them. Only bend them once, multiple bends will make it brittle.

Juntions rarely fail.

Make sure you hit everything with some PB blaster before you try to loosen anything.

"Flare wrenches" are handy to have if you want to throw a couple bucks at a set.

Flaring brake lines is an art that takes practice and gives you great pride or a heart condition.

And if this $300 tool is too expensive, I found that this $30 one works too!
(NOT a crappy clamp tool)

Oh how the other half live! I mostly get blank looks if I ask for that where I live - they will usually tell me that I mean the flexible ones...

...I'll say no...

...they'll say oh you mean a roll of copper tubing?...

...I'll say no just a painted steel brake line with pre-formed ends and unions...

...they'll say "go see the dealer"...

Just move here already. We will have you hooked on 0.73eu/L petrol and v8s in no time

Says the man rebuilding an OM617!

You mentioned replacing the brake lines instead of frigging with flare tool etc in the Caliper Rebuild thread. Did you use OE lines? Where they pre-bent? Did you try feeding one across firewall behind engine?

I had a look at Canadian Tire here today. They had many different lengths of metric (3/16"!) lines with bubble ends and from about 8" to 60". I was thinking of perhaps using 2 or 3 standard lengths with union connectors if installation in one piece is difficult.

https://dl.dropboxusercontent.com/u/...ke%20lines.jpg

I am hoping NOT to do this job, but It will leave me with one damaged flare nut.

If I remember correctly for my W123 it was the back ones I had trouble with (before I stripped everything out)

The dealer lines are not pre-bent. If you can get them elsewhere for less I would.