Vacuum issues and hello! - PeachParts Mercedes-Benz Forum

stahlvee · #1 06-10-2009, 05:38 PM

Hi,
I've just joined today and am glad I did. I tried looking for a good forum before I bought my car, but better late than never. This looks like a good one.
Anywho, I bought a '84 300D (with only 271xxx! )a couple weeks back.
It leaks a little diesel when the tank is full, but I'll tackle that issue later.
The issue I'm putting to you guys(and gals) is my vacuum system. Everything worked perfectly when I first bought the car. Just last week the car had trouble stopping. This happened a few more times and then I noticed locks were not operating either. I'm at the point where I have to pop the hood and press stop; the locks don't work. I'm not losing any sleep over it, but it'd be nice to fix

The automatic trans still shifts great and the brakes work fine.
I glanced at the diagrams and a few other posts. All those hoses: Just a little overwhelming.

thanks
-will

winmutt · #2 06-10-2009, 05:49 PM

Time to get a mighty vac and start pulling vacs and find ones that leak. Maybe just knocked something loose?

::matthew · #3 06-10-2009, 05:51 PM

did you change the oil when you got it? It's not uncommon to knock vacuum lines loose around the filter area.

carnut · #4 06-10-2009, 07:21 PM

Alot of vacuum lines are by the brake booster underhood. Can get disconnected when you replace the oil filter.

tbomachines · #5 06-10-2009, 08:22 PM

Oil filter change OR valve job you could have knocked one loose. However as long as the brakes feel normal, you can probably rule out the major vac line off of the pump.

Pick up a mityvac, those things are worth their weight in gold while troubleshooting these cars.

I THINK that there is a yellow vac line going into the firewall connected to the central locking system. It is easy enough to take the passenger door panel off and stick a golf tee in the lines (or pull vacuum with a mityvac), see what works and what doesn't.

Oh, and welcome!!

toomany MBZ · #6 06-11-2009, 08:29 AM

To help with taking the door locks out, for the time being, unplug that yellow check valve and plug off the connector that went to it. I used a new connector with one fewer connections. It can be tight in there, this was easier for me.

EDIT: Where is your fuel leak?

stahlvee · #7 06-11-2009, 11:33 PM

my fuel is weeping from the lines up front, but more seriously dripping from the rear of the car. this happens only when the tanks is past the half way mark or so. i'll have to take a picture of it, but since it only leaks like that when its full, i just haven't filled it up since :/

looks like i'll have to go out and but a vacuum tool. mighty(mity?)vac? any good online stores for that? haven't been able to do much diagnosing without one..
some of you mentioned the probability of something getting knocked loose from a recent oil change. while i haven't found anything loose or unplugged, it was a good suggestion. i had recently changed the oil and filter.
i did find out that the green vacuum damper valve doesn't seem to function, whatever it's supposed to do. air flows through it as if it was just another hose.

thanks for the continued support

tbomachines · #8 06-12-2009, 08:49 AM

I got my mityvac by going to froogle and searching for it. Get a decent kit with a metal hand pump, you'll be using it a lot! IIRC mine was $55, got it from an online place called S&J discount tools.

nhdoc · #9 06-12-2009, 09:32 AM

I bought a mityvac kit at sears 15 years ago and it is still going strong...I think it was about $30 at that time and I think they still sell the same one.

snookwhaler · #10 06-12-2009, 09:59 AM

I can concur with all of the above since I have been thorough all of this recently and now I have no leaks anywhere.

I will add this though. When troubleshooting leaks that you think are under the hood. I would disconnect and plug both the door locks/reservoir and the A/C control line. The climate control system is an area where lots of leaks usually reside due to old torn vacuum elements.

Getting a mighty vac will make things much easier. I got mine at Harbor Freight for $20. It is brass and it is a good one. The same one that Sears sells.

Be sure to check the line that runs down to the IP in front of and down by the oil filter. It sounds like this may be your problem. Inspecting and replacing all or most of those "vacuum elbows" would be a good idea too.

toomany MBZ · #11 06-12-2009, 01:50 PM

Quote:

Originally Posted by stahlvee

my fuel is weeping from the lines up front, but more seriously dripping from the rear of the car. this happens only when the tanks is past the half way mark or so. i'll have to take a picture of it, but since it only leaks like that when its full, i just haven't filled it up since :/

looks like i'll have to go out and but a vacuum tool. mighty(mity?)vac? any good online stores for that? haven't been able to do much diagnosing without one..
some of you mentioned the probability of something getting knocked loose from a recent oil change. while i haven't found anything loose or unplugged, it was a good suggestion. i had recently changed the oil and filter.
i did find out that the green vacuum damper valve doesn't seem to function, whatever it's supposed to do. air flows through it as if it was just another hose.

thanks for the continued support

The leak is probably the one or both of the rubber lines at the tank, I had 'em replaced in the SD. I had the same symptoms.

Mity-Vac type tools are available all over the place.

That green damper is just that, it will let vac flow, but not allow a "rush".

In the future, you may want to take pics before so you can hook everything back as it was.

MWatts · #12 06-12-2009, 03:20 PM

I just had the same problem, and wished I had tried the golf tee trick MONTHS ago!! It all started with my passenger door not locking when I locked all doors. This leak got worse, and eventually made it so I could not turn the car off without popping the hood and pulling on the throttle linkage. I pulled the yellow vac line coming directly out of the firewall, into the 3 way splitter, plugged the hole in the splitter with a golf tee...and the car turns off like a charm !!
I bought my mityvac from ebay, it is a handpump model, for $10.

Good luck!

jkubica · #13 06-12-2009, 08:38 PM

Quote:

Originally Posted by stahlvee

my fuel is weeping from the lines up front, but more seriously dripping from the rear of the car. this happens only when the tanks is past the half way mark or so. i'll have to take a picture of it, but since it only leaks like that when its full, i just haven't filled it up since :/

looks like i'll have to go out and but a vacuum tool. mighty(mity?)vac? any good online stores for that? haven't been able to do much diagnosing without one..
some of you mentioned the probability of something getting knocked loose from a recent oil change. while i haven't found anything loose or unplugged, it was a good suggestion. i had recently changed the oil and filter.
i did find out that the green vacuum damper valve doesn't seem to function, whatever it's supposed to do. air flows through it as if it was just another hose.

thanks for the continued support

Hi
If your just getting started with the vacuum system, you may wish to check out the vacuum troubleshooting pictorial at dieselgiant.com
Joseph

stahlvee · #14 06-18-2009, 01:48 AM

Quote:

Originally Posted by jkubica

Hi
If your just getting started with the vacuum system, you may wish to check out the vacuum troubleshooting pictorial at dieselgiant.com
Joseph

i checked out diesel giant.
looks like some good info.

thanks for your help guys. i got my bike running again, so i probably wont post in this thread for a while. at least until i do some troubleshooting with the future mightyvac