Rubber brake hose stuck - PeachParts Mercedes-Benz Forum

Codifex Maximus · #1 09-07-2012, 03:00 AM

I'm rebuilding the rear brakes on a 84 300TD Wagon and the calipers have wear on the contact area. Rotors are totally shot - eaten clean thru. Nothing left of the wear surfaces of the rotor but what looks like a rusted metal ring.

I've got all the new parts and am attempting to replace the rubber brake hoses. Only thing is... I can't get the old ones to come off!

Is there some trick to this procedure?!

I'm using special metal hose wrenches to avoid damage to the metal line. I haven't put much torque on it because I'm afraid of damaging the metal line. I'm using another wrench on the plastic side of the hose connection. I've inspected the new hose and the threads appear standard.

When I try to turn the 12mm metal fitting on the rubber brake hose, the metal line and it's 11mm fitting try to turn too. Put the special metal line 11mm wrench on the 11mm fitting to keep it from moving while I try to turn the 12mm. No go - 12mm side wont let go.

Searched the forum and found no previous instances of this issue. Advice?

t walgamuth · #2 09-07-2012, 06:01 AM

They can be a bugger. you might try heat. Of course you have sprayed it with penetrating oil? Also try moving the wrenches both directions, tighten a little then loosen a little.

In the end sometimes you end up having to replace the metal line too.

Its one of the pitfalls of owning a pretty old car.

Codifex Maximus · #3 09-07-2012, 06:23 AM

Sounds like sound advice t walgamuth. I've got all weekend to crack this nut.

vstech · #4 09-07-2012, 07:06 AM

the metal line should be 11 mm the rubber line should be 14mm wire brush the metal line nut, and SOAK it in PB Blaster or AeroKroil then get EXTREMELY HIGH QUALITY line wrenches. I recommend MAC or SnapOn brand, but NAPA brand have served me well in the past. nothing from craftsman or any of the MCPARTS stores are of high enough quality to avoid damaging the lines.
then when you are SURE you have the wrenches solid, align them where you can grip both in your hand and squeeze them together to loosen.

qwerty · #5 09-07-2012, 09:15 AM

Quote:

Originally Posted by Codifex Maximus

Advice?

Vice Grip #4LW. Beats the world's best line wrench hands down.

barry123400 · #6 09-07-2012, 09:26 AM

Strange to me that they should be that difficult in texas. Perhaps the car saw service in the north for part of it's lifetime.

Anyways when difficult use a torch set to heat the connection up. This is what I have to do quite often up here in the northern rust belt. Many times one of fittings has rusted down to a substandard size and vice grips become required.After the heating. The heating has burn off the ozidized layer of rust on a nut. Making it an odd size.

Penatrating oil of a decent type is the other possibility as mentioned if you can allow or have the time for it to work.

Maki · #7 09-07-2012, 10:01 AM

+1 on the 4LW. And use it to hold the hard line fitting immobile while you apply torque to the hose fitting. You can crank on that hard as long as you hold the hard-line fitting immobile. Apply torque to that fitting while the two fittings are tight together and you increase your risk of kinking the hard line.

Diesel911 · #8 09-07-2012, 11:47 AM

Someone mentioned in another thread that you can Cut the Hose and use a Socket on the Fitting (6 point might be better).

Once the Hose is cut a Box Wrench might also fit.

On the Metal End the Mentioned The proper Line Wrench (I used a 7/16 MAC Line Wrench but I don't think mine where as hard) special Vice Grips.

Codifex Maximus · #9 09-11-2012, 03:23 AM

I wish to thank everyone for their suggestions. I was offline for a few days and tried vstech's suggestion which, fortunately, worked.

However, I've got another problem now. The new hoses' metal fitting at the support bracket is too big to fit thru the mounting hole. I'm debating on whether or not to just enlarge the hole with a drill.

I can't leave the mount this way as it would eventually destroy the metal line due to friction.

Zulfiqar · #10 09-11-2012, 11:54 AM

off topic but related question. Are NAPA brake hoses acceptable to use on a W124?

Diesel911 · #11 09-11-2012, 04:19 PM

Quote:

Originally Posted by Zulfiqar

off topic but related question. Are NAPA brake hoses acceptable to use on a W124?

In theory the Brake Hose Material and maybe even the construction of the whole Hose is supposed to be DOT Approved.

So from a safety point of view it should not matter what company makes them.

That does not mean that you cannot get a defective one. Even back when most Brake Hoses were made in the USA it was possible to ge a defective ones (leaked around the crimped area).

The ones on My Mercedes I got from one of the local Auto Part Chain Stores and they were made by either Raybestos or Wagner; can't remember which. That was about 5 years ago.

The same with the Volvo; got the Hoses locally. In both cases I bought what was the least expensive. I have owned the Volvo since 1992 and that would have been about the time the Hoses were changed as every used Car I have ever bought needed a Brake Job and I always figured the Brake Hoses were the originals and always install new ones.

Zulfiqar · #12 09-11-2012, 04:23 PM

Im pretty sure my car has the OE brake hoses - they are supposed to be changed every 10 years or something ... thats why Im asking.

My older cars improved greatly with new hoses - I like to call them pipes though - for some reason it raises eyebrows in the US