My new England W204 suffers from rusting brake lines, mostly the rear passenger side where it travels along the axle carrier. I figured this is something i can replace myself. I've read some good threads on the subject and watched some informative videos. Though I still had questions, mainly what exact parts to use.

The car is currently at MB having a rusted exhaust manifold replaced so cant really look under the car to see what is there. On the brake diagrams I have it shows a hexagon spacer somewhere, looks like it connects two sections of brake line together. if I do have that under my car then ill replace the line from there back. If not then i'll cut and splice the hexagon spacer in. I stopped in the MB dealer earlier today and picked up a spacer and a brake line fitting. They fit together great so im assuming these brake fittings are what is installed in the car. I plan on buying a new flexible line to install at the rear caliper since I have a feeling the connections on the car are badly rusted.

heres the parts diagram:




I'd rather use Mercedes fittings when possible and I was confused about which sizes are installed. From my research they seem to be M10, whatever that means.



I found the part# for the fitting by looking up other diagrams that use the same brake line part #'s.















My main concern about replacing the brake line is having all the brake fluid leak out and I mess up the abs. if there is that hexagon spacer under there then it should be easy to unscrew the line and plug the end while I do the work. I have yet to see anyone mention these spacers though, or i just havent looked enough. In my case i'll be doing the rear passenger side. And from the diagram there should be two sections of hard line joined together by the spacer. Looks like the rear section of hard line is around 14 feet long.

I was thinking about buying that section of brake line from MB, its only $60 and comes with the fittings already attached. Im just not sure it is the exact size, will i still have to cut the line to the right size and flare one of the ends anyways?

Or i'll just buy a roll of brake line and a flare tool and try to make them myself.

I was thinking of getting a flare tool like the one below. Looks like its easier to use while the lines are still on the car.

 

Back to the diagram:



Red circle shows part 380- Hexagon spacer.

Green circle shows part 350- Line 4.75 x 0.7 x 1395mm. So thats around 4-1/2 feet long.

Blue circle shows part 360- Line 4.75 x 0.7 x 4290mm. Thats around 14 feet long.

Im thinking that spacer must be somewhere near the front wheel well?


I was looking at photos I previously took that has my brake lines in them. I noticed some type of protection on the brake line at the spring mounts. I think that is part 600 in the diagram. Part # 2014761126. But when I search that part # I get fuel line. Is that just a piece of fuel line on the brake line?

 

Ok, I think I finally understand. My issue was I kept seeing people recommend certain brake line kits they used and in those kits were a bunch of nuts, but to me they didnt look like they were the correct ones.

Am I correct in that the brake line kits on Amazon do NOT have the correct nuts? Heres an example of one I was looking at, it comes with a few different sized nuts:




I did some more searching around to learn what I am doing. It seems that the W204 brake lines use a DIN/ISO Bubble Flare? I drew the red X in below, my flare should NOT look like that, it should look like the one on the right?




This appears to match up with the parts I just bought, the hexagon spacer and the M10 Retaining Screw.



And the specific Retaining Screws/Nuts must have a "lead". Which looks like the Retaining screw I just bought? And the hexagon spacer I bought looks like the phot below.

 

I came across a video that seems to explain the difference with the nuts.

 

Now i'm wondering what brake line to use. I keep seeing people saying copper-nickel alloy is great, I see it for around $30 for 25 foot roll.

I was seeing how much the actual Mercedes brake line is. I found a few photos of it and got me thinking what material its made from. Looks like there is some type of coating on the outside To me it looks like PVF so searched around. Seems to match up with what im reading.

Now im thinking buying it from Mercedes isn't such a bad deal. Its $94 + tax. And figure it comes with each side flared and has two fittings. The fittings are $6 each and I do need two more. The description does note the line has to be adapted, im thinking one end cut to size and flared.

Id like to use the whatever will last longer, wont rust in a year, and is the easiest to work with and bend.

Heres the Mercedes brake line, for the passenger rear:

 

Rear lines on my 11 rusted out, I bit the bullet and bought the lines2go kit and only used the rear section, I’m an idiot and straightened out a section I shouldn’t have, so now I’m doubting myself because it doesn’t look as good as factory, I also took the opportunity to replace the rotors and pads and wouldn’t you know it, I broke the pad sensor bolt. So I walked away from it today because I wanted to set it on fire..lol. Anyway, hope it goes well and look forward to seeing the finished product.






QUOTE=TimC300;9050150]My new England W204 suffers from rusting brake lines, mostly the rear passenger side where it travels along the axle carrier. I figured this is something i can replace myself. I've read some good threads on the subject and watched some informative videos. Though I still had questions, mainly what exact parts to use.

The car is currently at MB having a rusted exhaust manifold replaced so cant really look under the car to see what is there. On the brake diagrams I have it shows a hexagon spacer somewhere, looks like it connects two sections of brake line together. if I do have that under my car then ill replace the line from there back. If not then i'll cut and splice the hexagon spacer in. I stopped in the MB dealer earlier today and picked up a spacer and a brake line fitting. They fit together great so im assuming these brake fittings are what is installed in the car. I plan on buying a new flexible line to install at the rear caliper since I have a feeling the connections on the car are badly rusted.

heres the parts diagram:




I'd rather use Mercedes fittings when possible and I was confused about which sizes are installed. From my research they seem to be M10, whatever that means.



I found the part# for the fitting by looking up other diagrams that use the same brake line part #'s.















My main concern about replacing the brake line is having all the brake fluid leak out and I mess up the abs. if there is that hexagon spacer under there then it should be easy to unscrew the line and plug the end while I do the work. I have yet to see anyone mention these spacers though, or i just havent looked enough. In my case i'll be doing the rear passenger side. And from the diagram there should be two sections of hard line joined together by the spacer. Looks like the rear section of hard line is around 14 feet long.

I was thinking about buying that section of brake line from MB, its only $60 and comes with the fittings already attached. Im just not sure it is the exact size, will i still have to cut the line to the right size and flare one of the ends anyways?

Or i'll just buy a roll of brake line and a flare tool and try to make them myself.

I was thinking of getting a flare tool like the one below. Looks like its easier to use while the lines are still on the car.

[/QUOTE]

 

I was thinking about getting the Lines-to-go kit. It looks like the rear passenger section should splice in at the drivers wheel well. There price is good and a great option.

The broken sensor bolt shouldnt be too hard to get out, small drill bit the one of those screw extractors. I had managed to break the plastic part that bolts to the caliper and have it held on with a zip tie. Since I want to at least replace that rubber brake line I was looking at used calipers on ebay, figure i can get a better rubber hose and a replacement sensor at the same time. I made the mistake of taking a wire brush to my calipers and mounting bracket and I guess i scrubbed off the protective coating. So my calipers are rusting and look pretty bad. Can pick up a used set of calipers in good condition for $60-$80.

 

I now realize that flaring tool I posted above is NOT the proper one. That tool will not create a DIN/ISO Bubble flare.

I searched around and was looking at a few on Amazon. Titan has one for DIN/ISO flares. They even had two "used-like new" for $29 so ordered that one.

I wanted the hand held since i'll be splicing the old line while still attached to the car. Looks pretty simple to use, just tighten the die in the tool and its done.

 

I have not used that particular tool before but you are correct to find a good one to use. A quality flare tool will make the job so much easier to do right the first time. I would make a few practice bends with it in the bench before messing around under the car. It’s not a terrible job to do just a little messy and I’d The bleeders won’t come loose that can be a headache to. Besides that i think you got this one for sure.

 

I found the PVF brake line already flared with nuts, can choose all different lengths. longest they have is 7 feet, so would need at least two lengths. So technically if the car does have that hexagon spacer installed on the line I can figure out the length and order accordingly, then just bend and screw it together using additional spacers. Wouldnt have to make the flares. The Mercedes brake line part # says it is 14 feet.






But I decided to go with copper-nickel brake lines. I found everything I needed at AGS https://www.agscompany.com/products/cnc-316-12/ . From reading about the different brake line materials im thinking the copper-nickel should not rust and it will be easier to bend and form the flares.

A 12 foot roll of 3/16 line was $6.99. I figure this is enough so I can replace the rear section that goes over the gas tank. I also bought a small 40" length of 3/16 line for $3.26 that has one end with a DIN bubble flare already on it, figure ill have something to look at and copy. It has different fittings/nuts on it so ill just cut one end and remove them. Then I bought 5 more M10x1 nuts and picked up another M10x1 spacer. Came to $22 with free shipping. I figure if i buy two more nuts from Mercedes that will come out to over $12, so this was a good deal.

Dont pay attention to the fittings on the brake lines below, those are going to be cut off since they are the wrong ones.

 

Ni-Copp is definitely the way to go for ease of bending. You can easily form it by hand without kinking. Actually, what I've found most difficult with the Ni-Copp lines is making straight sections! It's so easy to form it with your hands that it makes it hard to make it straight, if that makes any sense.

As suggested above, do some practice flares before you try one "for real". And if you have to flare a line that's on the car, keep in mind that's (apparently) steel, so you'll want to get a length of steel line to practice on, because it'll be quite a bit different than the Ni-Copp.

 

Good point. I figured the copper-nickel is easier to form where the original PVF line may break if I play with it too much.

I was thinking of bending everything up ahead of time using metal coat hangers to trace the lines on the car. It would be great if my car does have that hexagon spacer installed somewhere on the rear line, simply unscrew the line and plug it while I get the new line in. My car is ready so ill pick it up Monday and then see what is actually under there.

I ordered a tin of Dot4+ brake fluid on ebay for $15. I still have half a tin leftover from flushing the brake lines this past spring so thinking I shouldnt need much. I want to order some hose to go over the brake lines where it may rub but ill have to wait to measure the brake line to see what I can get away with. Wonder if just regular 3/16 ID fuel hose for small engines will work.

 

20+ years ago I bent some new lines to install on my Fox-body Mustang; I used the coat hanger technique when I was bending those, and it helped a lot to visualize things. Honestly, I'm not sure you'll need to use that method much with the Ni-Copp lines because they're so much easier to form, but it could still come in handy for spots.

 

I'll have to get under there but I remember noticing the line that goes along the gas tank is rusting, but the drivers side line actually looks good. My car is currently at the MB dealer getting some work done and they inspected the entire car for me and they pointed out the rear passenger brake line, they didn't mention any other sections. They even said the work should be done immediately. This is why im so gung-ho with doing it.

I was looking thru some photos on Pelican Parts to see how the lines are run, looks like the top corner in the drivers wheel well is a good spot to splice in the line.

Can see the rusted brake line going to the passenger side, top right: I have no idea how it got that rusted.



Its really rusted at the connection to the flex line: This photo was taken last winter when i replaced the shocks.




The drivers side line looks good to me.




If the rest of the brake line looks good im thinking here is a good place to splice in the new line: Top left corner somewhere. Can unhook the line and pull it away from the car giving me plenty of room to use the flareing tool.




Im noticing more of the rubber hose pieces on the brake line. I came across some silicone vacuum line, 5 feet for $5, wonder if its a good idea to just cover the entire brake line, protect it from damage due to being a softer brake line material. Im going to pick up a new "spring", its cheap and id rather not put back parts with rust on them. The MB dealer has it for only $1.70 so its cheaper than FCP.

 

I received the 3/16 double flaring tool and unfortunately it is missing parts. The Amazon listing said "Used-Like New and in original packaging" but instead it is just the handle part wrapped in a plastic bag. Contacted Amazon customer service thru chat and received a full refund and I can keep it. I could have just done an automated return but was worried about being blamed for the missing parts, explained this to the customer service rep, which she thought was a good point. I think it helped that I was super nice.



So I did the next logical thing, I looked on AliExpress and found one even cheaper. $15, what a deal. In the photos it looks just like this Titan tool so its probably the same quality. We shall see.

 

Got the car back and starting to inspect things. The rear passenger line is much worse than I thought. To me it looks like the corrosion/rust is at the bends, im guessing that coating was damaged when the lines were bent. From reading what they are theres just a coating over steel lines? Hope the new parts get here quick. I went ahead and ordered another flare tool off Amazon that should be here Thursday, I didnt want to risk waiting for the AliExpress one, even though it did ship out that day and tracking shows its on its way.

 

I had a chance to remove the plastic panel under the car and sure enough there is no hexagon spacer installed anywhere on the brake lines. Unless its up in the front wheel well, which I doubt.

Inspecting the brake lines it does appear that the drivers side rear has been replaced since it look to be in very good condition. The passenger side brake line that runs under the floor does not look as bad as the part going over the axle carrier. So for now my plan is to just make a new connection in the drivers wheel well and replace the line going to the wheel.

I seem to be having issues trying to upload photos.

 

I can't see pictures of whatever hex you are talking about, but I do not recall any when I cut and replaced mine.


From my video, you already know (but for others)
Basically I cut both from the side skirt and worked from there. I went with nickel copper and it worked fine. Bending is not difficult, just cut the old one out and mimic the shape like a pipe bender.

Obviously I don't recall all the details for the flares/fittings but one thing you should note is that it does not have to be a 100% match/100% straight etc. Sure, it should be roughly the same length, but this is not like it is coming out of the factory. It does not have any impact on air/pressure in the system. As you mentioned, once cut, I plugged the open hole until it was time to join, then bled when complete.

Ex. The CLS had a small part where following the factory path would have been impossible to install without removing the subframe. Went a slight alternative route which is still protected from the elements and saved a headache.
​​​​​

 

In the parts diagrams i have it shows the rear lines are actually 2 sections, and a hexagon spacer connects them. If you look for the part #'s it has 2 for each side, not just one. Oh well, i dont have the spacer, its just one solid brake line.

I dont think i can easily move the hard plastic line out of the way in order to make 1 entire line. Im thinking of making the connection somewhere around this location. Replace the rear section of line, then later on either replace the forward section or just redo the entire line. I think I need practice just doing it.

 

Heres the line under the car:

The drivers line (inner) looks newer.

 

How fast does the brake fluid leak out once you cut the line? Does it rush out, or does it just drip out? i just want to know how quickly I have to work. I went to Lowes and picked up an M10x1 bolt. My thinking is i'll cut the old brake line first, make the flare, then install the spacer. Use the bolt to plug the line from fluid leaking while I remove the old line and bend up a length. Because of all the small bends in the line i think its best to use the old line as a template.




Im seeing a few small bends in the rear line that I will try to replicate. I have a roll of silicone tubing I plan on installing over the brake line to keep it from rubbing. there are small sections of tubing on the brake lines under the car, can see a slit in them so they just installed them after the line was in place.

 

It isn't super fast but you can't leave it open otherwise it will all come out. I just plugged it with some kind of plastic cap. You'll want to practice flaring before you do that part because 1) you won't have maneuverability and 2) it will leak while you flare

Also this is a foolish mistake but when you're doing a lot of things at once, don't forget to put the joining nut on before you flare. It's easy to get sidetracked, flare, and realize you never slipped the nut on.

 

Received the Titan flare tool. This one was also listed 'used-Like new" and it does look new and not used, packaged isnt even open. This one was only $31.50. Says made in Taiwan. I still have the other one coming from China, see which one works better.

 

I received the brake parts from AGS and I do not like the fittings. The hexagon spacer is junk, the machining inside looks horrible. The nuts look good but they do not work with the Mercedes hexagon spacer, I do a test fit and the nut does not tighten the flare. Test fitting the AGS nut and AGS spacer the flare does seem to be fitting tight, but again i do not like the looks of that spacer.

The Mercedes brand nut and spacer work great so I will have to pick up some more.

I used the flare tool on the new line and the first one came out great. Its surprisingly super simple to do.

AGS junk hexagon spacer:






Bought a Craftsman mini tube cutter that works well.



I used a counter sink bit i had laying around to debur the inside of the cut tube:



Put the line in the tool, grease the die then just screw it in until it stops:









heres how the Mercedes nut fits:



The AGS nut feels loose and sloppy, the inside of the nut is tapered and doesnt push against the flare as good as the Mercedes nut.

 

Picked up more of the Mercedes parts at the dealer. I do not feel comfortable using the AGS stuff. The brake line looks good though. Wish I can figure out who manufactures the Mercedes nuts so I can just buy direct from them instead of paying $6 each.

I dont know if its just a quality thing but the AGS nuts look different from the Mercedes nuts. Different number of threads, the end of the nuts are different where the Mercedes have a flat shelf while the AGS nuts is tapered on the inside. The AGS look more for an SAE inverted flare.

If I try and screw an AGS nut into a Mercedes hexagon spacer it wont screw in all the way, its like the threads prevent it from going down all the way. I looked for other M10x1 nuts locally and they are all different from each other, different threads, tapers, it doesnt make sense to me.

AGS on Left, Mercedes spacer on the right. The hole in the AGS is much larger, it doesnt need to be since the Mercedes hole is the same diameter as the inside of the 3/16 brake line. The threads are machined different, AGS go all the way down.



AGS vs Mercedes nuts: mercedes are the silver ones.