car wont shut off, no vacuum.... - PeachParts Mercedes-Benz Forum

TurboSDL · #1 11-25-2009, 06:17 PM

after a 2 hour drive i went to shut my car off and it would not shut off. i took a look under the hood while it was running and removed some of the vacuum lines and there was no suction from any of them. is there anything that it can be other than a vacuum pump? Its a 85 300D. I have to drive it home sat night 120 miles too so if i have to get a part id like to know what it is asap so i can get whatever it is that i need..

how can i tell if the vacuum pump is bad or if its somthing else? thanks- Jason

Brian Carlton · #2 11-25-2009, 06:41 PM

Do the brakes work properly?

Skippy · #3 11-25-2009, 07:37 PM

If the brakes are working, your vacuum pump is as well. It's also possible for the vacuum pump to be working and NOT have power braking, due to a leak close to the pump. For a quick check, pull the line off at or near the vacuum pump and check for vacuum there.

Diesel911 · #4 11-25-2009, 10:27 PM

There is a Vacuum Valve on top of the Steering Wheel Lock and of course hoses that can come off or crack are there also.

I guess it is also possible for something to plug up the smaller Vacuum Lines and have your brakes still work.
If you have an Automatic Trans you did not say it was shifting hard; hard shifting would be another another indication of a Vacuum problem. If you are not having it your Vacuum Pump is most likely OK.

TOP · #5 11-25-2009, 11:36 PM

I once had this problem. Disconnecting the CLS and putting a golf tee into the open vacuum line to the CLS fixed the problem. Haven't yet found the leak in the CLS.

toomany MBZ · #6 11-26-2009, 09:53 AM

If you can get/borrow a vacuum gauge, hook it up to the main line, see what you get.
Usually there is a leak somewhere, the central lock system is the first place to check.
Do your power door locks work?

TurboSDL · #7 11-26-2009, 05:19 PM

ok so i drove it today and the brakes seem to be ok.... the trans could shift a little smoother and i had a leak in the door locks (i think) so i blocked off the line there.... my car shut off also when i turned it off, but all of the small vacuum lines dont seem to have any vacuum going thru them. do i hook up the vacuum gauge to the main black hard line? the one going into the booster is what im talking about.

is there a check valve anywhere in the main line? just a thought...

toomany MBZ · #8 11-26-2009, 05:54 PM

I understand there is a check valve in that main vac line where it bolts into the pump.
Unplug the nipple closest to the pump on the main vac line, block off the other nipple, stick a rubber connector there, what's the reading?
I also understand the second nipple has a pressure reducer of some sort.

TurboSDL · #9 11-26-2009, 11:03 PM

So r u saying to take vacuum readings on the main hard line? The thick plastic black one? I took off a vacuum line that seemed to be coming directly off the hard line and I couldn't feel any vacuum there either.. Tomaro ill hook up the vacuum gauge to wherever its best to hook it up... Should I just unscrew the line to the brake booster and check it there?

toomany MBZ · #10 11-27-2009, 10:22 AM

Hook the vac gauge up to the first nipple closest to the vac pump, that's it under my index finger. Plug off the second nipple, I just have my finger tip covering the opening.
The engine is not running, as you see there is no vacuum.

leathermang · #11 11-27-2009, 10:59 AM

I assume you know there is a manual shut down lever under the hood ???
So you do not have to do all your working while the engine is running.....LOL