Vacuum should only be applied to housekeeping

[Chopperguy7307]

I got my 300D back from inspection today, it failed. I need the following things: Right R. Brake Light and Back-up, Right Rear Tire, A small windshield repair and the fawkin IP shutoff fixed. The thing crapped out on me about 5 days before inspection and I've searched and searched for the vacuum info and tryed isolating the different systems. According to the inspector its the acutal solenoid that is not working. I considered this but the doorlocks arent working either. What do you all think. IMHO, Saftey inspection is BS. If my vacuum pump is FUBAR then I am SOL.

[sixto]

If the vacuum pump isn't working then you'll have no brakes.

Take a MityVac to the shut-off valve and see if that cuts the engine. Go from there. It's not a solenoid, it's a vacuum actuated lever.

Uhh... why wouldn't you check simple things like the lights before an inspection?

Sixto
87 300SDL

[ykobayashi]

You have a leak somewhere. Good tip about killing the pump with a mity vac and then working back.

You may need to go back through the ignition lock. If I remember the drawing right (go look it up on the DIY W123 site) your shutoff line goes into the firewall and into the key switch then back out the firewall and into the shutoff valve on the IP. Anywhere along here you'll have a leak or a crack or a disconnected line.

If your locks don't work, well, that is an indication that the vacuum system is disconnected or leaky...in fact, this is ringing a bell, I think if your locking system is leaking, that leak will steal vacuum from the shutdown system and you won't be able to get enough vacuum to shut down the injection pump.

I just fixed my locks and my recollection is that if you have leaky locks you'll lose vacuum in the other circuits too like your climate control flaps and most importantly your shutdown circuit. Make sense? If you are trying to pump down all the circuits - locks, flaps, shutdown, cruise control, egr etc. and one has a gaping hole in it, you will loose vacuum and none of the others will work.

When I fixed my locks (search my informative thread) the last thing I had to find was a BB somebody stuffed into the lock line source. The reason was the locks had bad leaks that would leave the shutdown non-functional and since the smart person who "fixed" the system didn't know exactly where the leak was, he just plugged the main vacuum line to the locks. You may need to do this too (to your locks and other leaky things) if you just want your shutdown to get you through inspection.

Hope you solved your tailgating problem too.

Cheers,
Yoko

[Chopperguy7307]

would a brake bleeder hand vacuum work? I dont want to go around buying new tools to fix one problem I may never have again. Whats interesting is the guy who did the inspection said it was the lever, and nothing else. He wanted $544 to fix the whole car including the tire. This price also reflected the $155 shutoff thingy. To tell you the truth I dont think this guy has worked on too many MB's.

And yes, the tailgater is no longer a problem.

[sixto]

Try it with your bleeder device. It should cut the engine fairly quickly. If it takes 20 inHg to cut the engine the shut-off valve is on its way out.

Sixto

[boneheaddoctor]

Originally Posted by Chopperguy7307

would a brake bleeder hand vacuum work? I dont want to go around buying new tools to fix one problem I may never have again. Whats interesting is the guy who did the inspection said it was the lever, and nothing else. He wanted $544 to fix the whole car including the tire. This price also reflected the $155 shutoff thingy. To tell you the truth I dont think this guy has worked on too many MB's.

And yes, the tailgater is no longer a problem.

the shutoff valve is $66.50 and takes all of 15 minutes to install....

http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1MY1ATEJJ1N613CW16&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1984&product=D2020-11537&application=000004561

And that assumes your old one is defective....have you checked the lines yet?

[sixto]

For a really crude check, with the engine running, attach a hose directly between the tee in the brake booster line and the shut-off valve. Leave the other lines hanging. If the engine shuts off, the problem is with the hoses or the key switch.

Sixto
87 300SDL