Fix one thing, break another. Someone tell me what I've done... - PeachParts Mercedes-Benz Forum

muleears · #1 10-04-2010, 05:40 PM

While working on my lift pump. This is on the '85 123. I broke the vacuum nipple in the attached pic. It is on the main line that runs from the vac. pump to the brake booster. Sorry for the fuzzy pic, but you can see the stub of the nipple sticking out of the vac. hose I am holding and the spot where it broke off. I'm not sure what this does but I am sure I need to fix it. Someone please fill me in.

jonbobshinigin · #2 10-04-2010, 05:54 PM

You can either try to glue it and "band-aid" it or replace it. The part is called a Brake Booster Line. It costs about $30 and takes just a second to replace. Until it is corrected, you will need to pop the hood and shut the engine off manually. This is one of the first things I "broke while fixing" myself. The old plastic is quite brittle!

Brian Carlton · #3 10-04-2010, 05:56 PM

Everybody breaks that nipple sooner or later............

You got two options.........one proper and one cheap

1) The proper option is to replace the entire hose from the dealer. They don't sell only the nipple and connector.

2) The cheap option is to drill out the nipple and replace it with a small piece of brass tubing that is lightly pressed into the plastic and secured with JB Weld. Some folks have been successful with this.

funola · #4 10-04-2010, 05:56 PM

Don't feel too bad. That thing is old and britlle after all these years and don't need much to snap it off. Mine broke in the exact same spot. There is easy salvation:

Use a 1/2" length of 1/4 in o.d. x 1/8 i.d vacuum tubing (silicone tubing is best but others will do). Drill a hole in the broken vacuum line to a size that's a tight fit so you can shove the 1/4 tubing (with a short section of the Mercedes hard 3/16" vacuum line shove in the 1/8 hole). Splice it to where it has to go. Mine has been working fine like this for couple of years.

Alastair · #5 10-04-2010, 05:56 PM

Hmm, Thats a nasty little issue...

Not sure exactly What that vac supply actually does, My 1985 W123 only has the one nipple on the main vac. line which supplies the vac system of the entire vehicle...

Inside the part thats broken off, will be a restriction I'm guessing, which is of a metered size...
--The system will use this in relation to other metered 'leaks' and valves to apply a certain Amount of vac to those components it supplies (whichever they are in your case--I'm gonna guess its the climate-control --or--the rest of the car)

(Mine does not have AC etc, and I know the AC is all vac operated, so just a guess...)

Personally, I would remove the main line and the nipple from the rubber pipe and carefully repair it by using sunnit like JB Weld or some epoxy, taking care that none actually blocks the passage through the nipple...
--At least thia will get you working again till you can find one at a breakers/buy a new one etc....

Billybob · #6 10-04-2010, 06:20 PM

Quote:

Originally Posted by muleears

While working on my lift pump. This is on the '85 123. I broke the vacuum nipple in the attached pic. It is on the main line that runs from the vac. pump to the brake booster. Sorry for the fuzzy pic, but you can see the stub of the nipple sticking out of the vac. hose I am holding and the spot where it broke off. I'm not sure what this does but I am sure I need to fix it. Someone please fill me in.

A 3/4-1" section of 3/16" steel brakeline epoxied into place after drilling it out just large enough to fit snuggly is a quick and dirty fix that can last for years!

dieseldan44 · #7 10-04-2010, 06:28 PM

Its the W123 equivalent of a parking ticket.

Pay the brake-booster-supply-nipple-break-off fine of $30-40 and move on.

5 minutes to replace once you have the new one.

muleears · #8 10-04-2010, 06:29 PM

Thanks for all the rapid and useful replies! You have given me several ideas to fix it. However, I was just driving the car and I noticed nothing... It appeared everything worked. It even shut off properly. Is that all that vacuum line does is power the shut-off valve?

Fattyman · #9 10-04-2010, 06:52 PM

There are 2 fittings on that line. One of those is dedicated to the shut off circuit and the other for door locks and climate control. That way if you get a leak somewhere in the car you can still shut off the motor. Unless the leak is really bad. Take a look at the vacuum lines at the firewall and see how they are attached. Yellow lines for door locks, green line for climate control, brown for shut off. The answer to your question will be found there grasshopper

Now you know why I take my vacuum line off whenever I'm working around it. Been there, done that

ImBroke · #10 10-04-2010, 06:56 PM

Cal, I should have an extra one. I'll have to check my stash next weekend.

muleears · #11 10-04-2010, 07:51 PM

Quote:

Originally Posted by ImBroke

Cal, I should have an extra one. I'll have to check my stash next weekend.

Thanks Tony, I'm gonna try one of the "cheap" repairs and see if I can make do that way. If I can't, I'll see you about the one you have. Don't wanna waste your good one if I can fix what I have!

vstech · #12 10-04-2010, 08:04 PM

I'll tell you what I did.
snip a bit off of the straw that comes with brake spray or wd-40 and put it in the nipple a bit. then coat the outside of the straw and the fitting with the PLASTIC epoxy jb-weld stuff.
push it together, and let it cure for the recommended time on the package.
mine is still in place and it's been a year...

#13 10-04-2010, 08:24 PM

Join the club, I think I've broken mine about three times (so far).

vstech · #14 10-04-2010, 08:26 PM

I broke one of mine 5 minutes after teaching a customer how fragile the parts are in there, and to be extremely careful when changing oil and working on the motor mounts.
then I go in, start changing motor mounts, and break mine...
AAAARRRRRGGGGGHHHHH!!!!!

daw_two · #15 10-04-2010, 08:39 PM

The first 300D I owned, I broke that nipple during the very first oil change. This club has a lot of members!!!