Front Brake Line Replacement
on the 1982 300CD (W123.153)
by JHZR2
03/10/11
Front Brake Line Replacement DIY
When doing front-end on my 82 300CD, I noted that the brakelines had some bumps in them. I certainly didnt want to take any chances, so I replaced them.
Tools:
- Box-end line wrenches
- 14mm box/open wrench
- Penetrating fluid
- Pressure bleeder (optimal)
My car has Bendix calipers. Others should be the same, as there seems to only be one front brake line part number.
Failures may look like this:
It is best to sparingly use penetrating oil at the point where the hose meets the caliper. They can be VERY tight, and you dont want to damage anything.
You could loosen the caliper-end or the top section first. I did each one different. Be ready for leaking brake fluid, which can damage paint.
I'd recommend doing the caliper side first and then the top section, so you can direct the drainage of fluid easier.
I found that a 14mm open end wrench worked best for the caliper side.
Then use the line wrenches to remove the rubber line from the hard line. This may be doable with open end wrenches, but I certainly didnt want to chance harming the hard lines.
It is easiest to first remove the wire clipped in for the brake sensor, then access the lines.
Remove the top section then install the new line by threading in at the bottom:
Then attach the top to the line.
Tighten up with the two-wrench approach.
Be careful with the clips that the sensor wire was removed from. When reinstalling, one of mine snapped. I then wrapped the line with electrical tape and wire-tied it to the joint assembly.
Since the brake system was opened, it needs to be bled. Youll need a box end wrench and something to collect fluid. The box end can slip over the bleeder to make the job easier.
I like to use a motive pressure bleeder. Makes it easy to do with one person. The best way to do this (or bleeding in general) is to remove the cap on the reservoir and suck out the old fluid.
Then attach the bleeder and pressurize to about 5psi.
Open the bleeders and push fluid through. It is good to gently tap the calipers to help get air out. I do the farthest one first, then move sequentially closer, and then repeat.
There will be alternating bubbles and fluid, sometimes the fluid will be dark. Make sure that there is a steady flow of brake fluid so that there is no chance of air in the system.
Done!
Discuss this DIY here.
-JHZR2
CategoryDiy
