Weeping Brake Fluid from Braided Hose at Reservior
 

While doing my valve adjustments and diesel purge today on my '82 240D (4 speed), I noticed something amiss:

A braided hose (circled in red) leading from my brake fluid reservior and into the firewall was seriously deteriorating and weeping brake fluid, with the fluid building up on top of the inside fender well.

I wiped off the hose before taking the car on a short test drive around the block. During that short run, the hose had already started to get soaked again with brake fluid.

In the interest of safety, I have parked the car for now, until I can fix whatever is causing this.

Questions:

1) Where does this hose lead to? It looks to me like it goes inside and under the dash. Why would that be? :confused:

2) Can/should I replace it with something better than braided fabric?

3) Also, the nipple that the hose fits onto on the brake fluid reserviour seems rather short, and there's no hose clamp. The hose is very frayed where it goes over that nipple. Should there be a hose clamp there?

Thanks,

- Patrick

my guess is its for the clutch. my sd is an auto and it has that nipple sticking off but no hose. the clutch is my best guess

Yes that hose is for the clutch. MB has started making those braided hoses out of a really durable rubber hosing when you go and get OEM replacements, I found this out when I got new fuel hosing from the dealer, the old braided stuff has been superceeded with a thick strong rubber hose.

Looks like some blue VW master clyinder resivour tube would probably work.

The PROPER hose is press fit and thus you don't need a clamp. There is a barb on the end of that nipple that holds things on very well. After you put your new hose on, try to pull it off. Assuming it is the right stuff and has a cloth-like outer covering, you won't get it off. :)

And yes it goes to the clutch...found this one out a couple days ago :)

I'm afraid it failed due to old age. You are going to have to replace it every 20 or 25 years from now on.

The original hose has a woven covering that acts like a chinese finger trap and needs no clamp. You could substitute neoprene fuel line or clear plastic. The clear line doesn't need a clamp as a rule, but if you want to put one on, small plastic tie wraps work well for mini hose clamps.

While you are under the hood, check all your fuel lines, radiator hoses, heater hoses etc. If they are mummified and hard, or soft mushy and swollen it would be a good idea to replace them now before you get stranded on the road. Like I say, this is normal maintenance and will need to be done every 20 or 25 years.

The plastic nipple that the hose fits over is not very strong, especially after 20 years. Therefore, be extra careful when removing the old hose. If it fights you, you may want to consider cutting it away from the nipple.

If you make an error in judgment here, you are looking at a new reservoir. :eek:

I once did this with a heater core. The hose decided to be a giant PITA. I, being the stronger of the two of us, won the argument. The copper pipe nipple that extended into the heater core did not. :mad:

I won't have any trouble getting it off. Indeed, when I go out and look at it again, I'm amazed that it hasn't fallen off on it's own. I think I am lucky it didn't fail out on the road.

So the piece that goes through the firewall goes to the clutch? What's my best bet for changing that hose out? Do I need to pull my instrument cluster?

Or can I disconnect it at the other end (where is that?) and pull it through? :confused:

Thanks,

- Patrick

Don't pull on ANYTHING yet!! You'll make a mess!

Before proceeding any further with this repair, make sure you have the tools and are capable of bleeding the brake and clutch hydraulic systems. You may be able to perform this without having to bleed the system but, it would be best to be prepared. For more info on bleeding cluch and brake systems, search the forum.

The hose you need to replace runs from the reservoir (where you see it leaking) through the firewall, to the clutch master cylinder. The master cylinder is attached to the clutch pedal assembly and is hidden from view by the valence that is directly over the foot area on the driver's side.

To access the master cylinder, remove the valence (three screws at the top back edge next to the black part of the dash and one other screw/fastener of some sort, above and in front of the parking brake pedal). The master cylinder looks like this:

http://img.eautopartscatalog.com/live/I300011980FAG.JPG

The hose from the reservoir goes to an angle fitting that is a press fit into the rubber grommet next to the mounting holes on the master cylinder.

Before going any further, remove the floor mats and carpets from the driver's side floor and suction the brake fluid out of the reservoir until it is below the level of the molded-in clutch line nipple. If you remove this line without removing the fluid, you will drain a large part of the contents of the brake reservoir onto the floor of your car.

After the fluid has been removed, pull the hose off of the master cylinder angle fitting (some fluid will drain out of the hose and the cylinder). Then, remove the hose from the reservoir and pull it out through the firewall.

Now, cut the new hose to the same length as the old hose and push it back through the firewall opening. Attach it to the master cylinder angle fitting and then to the reservoir nipple.

Refill the reservoir with new brake fluid and bleed the system.

Test clutch operation

Check for leaks. Clean any spilled fluid and replace mats/carpets.

I wish I had that leaky hose......It would mean I had a standard tranny....

Or you could cut the bad part off the old hose and shove it back on. Would probably be OK for another 5 years.

Great idea, but I don't know if I've got enough hose length for that.

The hose that I can see appears to be getting soaked. It's the hose that I can't see that I'm worried about, too.

So I think I'll just replace the hose and then not worry about it for another 20 years.

That also gives me an excuse to buy a pressure bleeder and do my brakes, too! :)

- Patrick

I followed R Leo's guidance and removed the lower valence below the dash. Using a flashlight and a small mirror, I have examined the entire length of hose. It is soaked, and today I had a small puddle of brake fluid on the inside fender.

Question: is this hose the same diameter and material as other hose in the brake system?

My concerns are twofold: is there similar hose in the brake system that is about to fail; and can I buy this hose in quantity and save some money?

I'll take this opportunity to power bleed all the brake fluid, starting with the clutch and then working (one at a time) from one brake to the next.

I'm learning a lot here. I'll continue posting what I do, and any "first timer" mistakes that I make.

Thanks!

- Patrick

[QUOTE=PatrickW]I followed R Leo's guidance and removed the lower valence below the dash. Using a flashlight and a small mirror, I have examined the entire length of hose. It is soaked, and today I had a small puddle of brake fluid on the inside fender.

No. All other hoses in the system are proprietary. They have swaged ends with threaded fittings in order to operate under the pressures required to actuate the brakes or clutch.

You should inspect all other flexible hoses in the brake system on principle; replace if needed with a Mercedes-Benz™ part or one from a reuputable aftermarket supplier.

However, the clutch supply line that you see leaking can be bought by the foot at any decent automobile parts house. An 'official' MBZ part is not required. I cannot remember the exact size but it is either 6mm or 8mm ID fuel hose. Similarly-sized SAE diameter hose will also work; it just needs to be a tight fit onto the barbed nipple.

Brian, it fell off on it's own today. Made a real mess, too :mad: Hose was splintered, swelled, soaked and rotted.

Can't MB make a hose that lasts more than 24 years while containing brake fluid under pressure in the engine compartment? ;)

On my way home from work I stopped at the local MB dealership to get some hose. Of course they didn't have any on hand, but were willing to $pecial order me the exact ho$e :rolleyes:.

I just cut a piece of it off and stuffed it in a baggie. Tomorrow, on my way home from work I will drive by a Checker Auto Parts and a Napa store. I'm sure one of them will have the hose I need.

- Patrick

Well, fortunately, you didn't need to fight with the plastic nipple. Those fights usually result in: you lose. ;)