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Summary: Make sure to open brake lines when replacing front brake hoses to drain brake system but do not let the master cylinder go dry. Open brake lines when replacing front brake hoses with the tips in this free video on car repair from a professional mechanic.
Mark Blocker is a semi-retired ASE-certified master mechanic with more than 20 years of automotive experience. He has been a state-certified emissions specialist for more than 15 years...read more
"Okay, in this segment we're going to cover removing the brake hose. And we're also going to cover installing the brake hose. Now we're going to combine the two segments together 'cause it's kind of an important situation. When we open this brake line up, when we remove either into the fitting, that opens the brake system and gravity is going to cause the fluid to start dripping out of the system. What we don't want to happen is, that master cylinder to go dry, regardless of what the situation is, we want avoid that at all cost. We can cause damage to the master cylinder, in attempting to bleed it and get it function again if it goes dry and it cause a whole another procedure and a lot more time to get the system bleed out correctly. So what we want to do is remove this brake line and install the new one and get it tighten down and stop the leakage as quickly as possible so we prevent the master cylinder from going dry. Should we run into difficulties, a tight knot, any thing that could slow you down and prevents you from get it done in, you know, you probably get three to five minutes to work with, what you need to do is stop, tap off the master cylinder again and then a little bit extra brake fluid loss is a lot cheaper and a lot less aggravation and a lot less time than have to bleed the master cylinder. So, if you have any question in mind while you're working on this, just pop the head up and give a quick look at the master cylinder and get the fluid level. If it getting down to where it's low, just tap it off and you got plenty of time to continue working. So what we want to do is lay out the tools that we're going to need to remove this. First thing, the cable's mounted in the middle and attach here on this vehicle, it uses a 8 mm bolt with a 12 mm heads, we're going to want to have a socket arrange to fit that. We need 14 mm to fit band gel fitting. And up here, where it's connected, we need 10 mm wrench and a pair of pliers because there's a clip that fits right in here, that slides into a bracket and it clips slides through here and that locks it up or holds in place. So you're going to want a pair of needle nose pliers, standard pliers or channel locks style pliers to grab that clip and just remove it. You can also, sometimes get accessibility with stage screw driver and pry it out. So you want to get those three tools rounded up at this time. Then what we'll do is break this top connection free, just crack it free and loosen it so that we know it's free of moving and we'll snug it down and then we'll remove the lower one first. But prior to doing that, we're going to take out the bolt that holds the cable firmly on this sprocket, because that will prevent us from getting it in and out. Have the other one laid out. Your new cable should came in with a little wire tie and two new either brass or copper band gel fitting rings and those are the two washers that go on each side of the band gel bolt that goes through here as a seal and you want have those set aside. Those items you'll need to have, right on hand, in your hands when we start this, 'cause you don't want to have to get up chasing down tools while your brake system is leaking. Okay, that will conclude this portion of removing and installing the brake hose. Please do watch our next segment and we'll cover part II of removing and installing the brake hose."
eHow Article: Replacing Front Brake Hoses: Open Brake Lines