Hi,

I need to replace cracked front brake flex hoses. The question is, once I undo the 11 mm nut upstream, how do I prevent brake fluid from leaking out? I want to plug the line somehow so I have some time to disconnect the old hose on both ends and then route the new hose in place.

What is a good way to plug the line? I tried a golf tee, but the fluid still leaks around. I am thinking about electric tape around golf tee and metal part of brake line. Is there a better solution? Can I create a vacuum somehow so the fluid does not leak out form the metal line? I have a brake bleeder which I never used. Can it help to prevent the fluid from coming out?

The car is 2008 E350 W211 4MATIC.

Thanks.

 

It doesn't matter if it leaks out. You'll have to change the brake fluid and bleed the brakes when you're done.

 

Ditto on bleeding the brakes anyway. You might need scanner to bleed ABS unit, but with some luck you might do pressure bleeding with no additional issues. Just don't turn the ignition before you finish.
Why you have to replace the hoses? I did replace those on father's W124 at 29 years mark and that was still "preventive maintenance"

 

Leave the brake fluid cap on the reservoir so you don’t risk air getting anywhere above the brake line you remove otherwise it can be a nightmare to bleed it clear. Just plug the line after you remove to keep air risk minimal.

as said above you must bleed after regardless

 

I have used a tire valve stem... works pretty well each time I have used it. It will be a tight fit but no leaks.

 

This is done, so I am sharing my experience. To replace both hoses (one on each front side) I needed to unscrew four 11mm nuts. It is better to do with line wrench which, unfortunately, I did not have. With open wrench there is a risk of stripping the nuts, but I tried to be very careful. First step is to top off the brake fluid, just enough to be able to close the cover. Close the cover tightly. Second, I loosened every nut and tightened them back just slightly. This is to make sure that once I open the system I will not get stuck with a rusted nut on the other end of the hose. Third is to remove the hose from the grommet on the strut mount. This is done by simply pushing it out of the grommet, but in my case required some force because of dirt around it. Then I unscrewed a top nut on the brake line on one side (for example, driver), gently pulled the metal brake line up and pulled the hose down. The hose has 2 notches (on each side) that go through metal plate. So, I needed to make sure that these tabs are aligned during removal and installation. Once I started unscrewing the top nut the brake fluid started to come out. It looked like I had a few minutes before I would have to refill the top reservoir. From here the goal is to try to unscrew the second nut, remove the old hose, clean dirt and debris around the connectors, align the hose connector tabs and put new hose, align the mounting plates, and screw both nuts back as quickly as possible. It took me, probably, about 2 min on each side and I lost about an ounce of fluid total, which, I think, is not bad. However, with all this I created some mess and had to clean it up with paper towels.

Now the bleeding part. It is the same 11mm wrench needed for the bleeder valve. It seems I could get away without anything complicated. I attached a clear hose and opened a bleeder valve on one caliper. Then I realized that the gravity will take forever to bleed it. So I used Motive Products, European Power Brake Bleeder, 0100, attached it to the break reservoir and set it to about 3 psi. It took about 30 sec to get an ounce of fluid out on each side. Once I saw no bubbles I closed the bleeder valve on a caliper. Then I repeated this for another side. Test drove the car. Brakes seem firm.