My vehicle:
1985 300CD-T (California)

Issue:
At the right rear wheel, I am having difficulty removing the flexible rubber brake hose where it connects to the steel brake line.

Background:
The flexible brake hoses on my vehicle are 15 years old I know, I know.
Of all the work I have done on this vehicle over the last 15 years, I have never replaced these hoses.

Using a 14mm box wrench, I have successfully loosened the hose end at the brake caliper.

I am thus far unable to loosen the hose end at the steel brake line.
I have used a bit of MAPP gas on the fittings here to try and loosen things up, but no luck so far.

I am puzzled over the connection of the flexible hose at the steel brake line. Specifically, does the 11mm nut that is on the steel line move or is it welded to the steel line?
I have noticed that the u-shaped bracket on the hose holder that is underneath the 11mm nut will spin under the nut...

Should I be holding the nut with the 11mm wrench and using the 14mm wrench on the flexible hose to loosen the hose? Is the any reverse threading at play here or are the connections the normal clockwise to tighten and counter-clockwise to loosen?

I'd appreciate any clarification here. I have used as much force as I feel comfortable and think that unless I understand exactly how this assembly is put together, I may break something if I up the force.

I would any clarification or advice on this one.

Can you post a good picture ?

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Can you look at the NEW hose and see how it is screwed together? It is quite simple. May be the bracket is in the way. Or you can try to undo the other side if you are going to replace both or all 4.

I do not do it often so I cannot really visualize it to give a good description.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Sure thing and great idea, too! Duh, why didn't I think of that? Answer: I switched to decaf. coffee lately...

One more thing:
To my great surprise, there is *nothing* that I can find in the Factory Service Manuals or even the Haynes book (I know), that discusses replacement of these hoses. Weird.

Picture attached.

Thanks-

Attached Thumbnails

   

i think the design of that bracket, with the tensioned spring like metal piece, is supposed to hold the nut, but it doesnt really work that way. get a 11mm on it. theres no reverse threading.

also: make SURE it's a line wrench or flare nut wrench. you dont want to put a regular open end wrench on there and round that nut off! its really easy to do!

__________________
1981 NA 300D 310k miles

Thank you for all of the quick and helpful advice!

I have attached four annotated pictures here so that anyone who gets in this predicament in the future will see how I managed through this little challenge.

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And I completely agree with Sleepstar:

I have decided to re-tighten the hose and put this job off until I have a line wrench or flare nut wrench.
I'll plead ignorance: I did not know about these wrenches (nobody knows everything even after 15 years of work on a car!) and I did slightly round this one nut. Nothing horrifying but now that I understand what a line wrench or flare nut wrench does, I will do the work properly once I have those wrenches!

Thanks!

The trick is to hold the flare nut immobile while turning on the hose fitting. Do not try to turn the flare nut while the fitting is tight or you'll risk kinking the hard line.

I've recommended this tool before for gripping flare nuts on tubing: the Vise Grip 4LW. Others have found it effective as well -- search the forum archives.

Thanks for posting this w/ photos. I have never replaced rear brake hoses on a 300D. The thing I don't understand is that the bracket usually prevents the hose from rotating. It appears to have a "double hex" punch-out for this purpose. If so, how were you able to rotate the hose relative to the bracket? Also, was there a C-clamp on the upper side of the bracket which secured the hose? I have only SAE flare wrenches (inches), but recall using them fine on my newer U.S. cars which have all metric fittings (I think). Perhaps they fit metric tube nuts, since some metric & SAE sockets happen to be identical.

I found no indication whatsoever that anything associated with the bracket (referred to as “holder” in the Factory Service Manual [FSM]) would prevent the hose from rotating. The hose appears to first fit through a round hole on the underside of the bracket and then fit through the u-shaped clip thing (not referred to at all in the FSM) and then attach to the steel line by way of the 11mm nut that is attached to the steel line. I see no evidence on my vehicle that the bracket has a “double hex punch-out” but rather, appears to simply have a round hole (I will know for dead certain about this once I have removed the hose completely, pending my acquiring the 11mm flare nut wrench). The fact that turning the end of the hose with the 14mm box wrench caused the top of the hose/steel line to turn uniformly indicates to me that, again, the bracket itself does nothing to prevent the hose from rotating.

Where you write, “…a C-clamp on the upper side of the bracket which secured the hose?”, perhaps you are thinking of what I referenced above as, “…the u-shaped clip thing” that is shown in my first picture above and posted at 12:12 PM today. This item does and will spin free, 360 degrees even when the 11mm nut is tight. The function of this item, I surmise, is such that when it is bent upward enough (like a dog standing and arching it’s back), it keeps the hose pulled tightly into and against the bracket.

The bracket hole is not supposed to be round...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Well, I recently completed successfully replacing the 4 rubber brake line hoses (among other things) on my 1985 300CD-T (Calif.) and for those who might read this thread in the future, following are some comments and pictures...

1. As BillGrissom and vstech previously pointed out in this thread, each bracket for each brake hose DOES have, on its underside, a "double hex punch-out" (see attached picture "1"). This thus means that with the hose properly installed at the bracket and connected to the steel brake line and for de-installation, one must NOT adhere to the following text posted on this thread previously:
"The trick is to hold the flare nut immobile while turning on the hose fitting. Do not try to turn the flare nut while the fitting is tight or you'll risk kinking the hard line." Quite the contrary. Due to the aforementioned "double hex punch-out", the hose is locked, so to speak, into the bracket. One should thus use a 14mm box wrench to hold the hose steady and immobile while using an 11mm flare nut wrench to loosen (counter-clockwise) the nut that is on the steel brake line.

2. Once step 1. above is fully completed (that is, the rubber hose is fully disconnected from steel line), THEN the other end of the rubber hose can be de-installed from the brake caliper.

3. Re-installation is the reverse of de-installation.

4. I used a new metal clip that fits underneath the steel line's nut at each bracket. See attached picture "2" (this is at the front left wheel well).
Part #000 995 66 65. 4 required for vehicle.

5. Notice in picture "2" the black plastic bracket clip that is situated underneath the metal clip mentioned in 4. above. As you can see, the purpose of this bracket clip is to secure the cable from the brake pad wear sensor assembly. My originals were brittle and I replaced them. Part #126 546 07 43. 2 required for vehicle.

6. Yes, in picture "2" the brake pad wear sensor assembly cable looks new because it is. The cable sheathing on my old sensors had cracked open and thus, I replaced the sensor on each side.

7. Picture "3" shows the steel brake line passing through its grommet and the brake pad wear sensor's cable passing through its grommet. My old grommets were deteriorating and thus I replaced them. Part #001 997 14 81 (brake line, 2 required for vehicle), part #126 997 28 81 (sensor cable, 2 required for vehicle).

8. The PowerBleeder is an outstanding product for one person brake flushing/bleeding.

9. Use a flare nut wrench on those 14mm nuts on the steel brake lines or you'll likely round the nut and that will only complicate your life. I saw the wrenches at Lowe's. I obtained mine through Amazon before I discovered them at Lowe's.

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I wouldn't worry too much about 15 year old brake lines. The lines on my 87 190D were original when I replaced them this year, as told by the manufacture date on them.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.