1980 300td no shutdown - PeachParts Mercedes-Benz Forum

joro · #1 09-07-2008, 01:41 PM

I have some kind of vacuum leak,so at times not always the car wont shut off by turning off the key,i also have a hard time turning it off at manual shutoff in the engine,i have to accelerate it then press down for it to stop,does this ring a bell to anyone?

Chad300tdt · #2 09-07-2008, 01:47 PM

Do you have any other symptoms of a vacuum leak, like issues with the central locks? You might need to replace your shutoff switch.

joro · #3 09-07-2008, 02:01 PM

central locks work when car is on,after a while of sitting they dont work,what does the off switch lok like? got a pic?
Thanks you
J

Chad300tdt · #4 09-07-2008, 02:08 PM

Here's a pic:
http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2ER0I2KSF2GJ0U904B&yearid=1980%40%401980&makeid=MB%40%40MB%40%40X&modelid=300%2DTD%2D001%40%40300TD&catid=D%40%40Diesel+Injection&mode=PA&subcatid=D2020@@Shut+Off+Valve&source=www.peachparts.com&clientid=catalog.mercedesshop

Maybe you just need to replace the 2 gaskets it mentions in the link from Fastlane.

I would get a Mity Vac and start testing everything. You might want to block off the central locks from the system temporarily (the yellow check valve at the firewall by the oil filter housing) to make a quick determination if there is a leak within it that would be causing the problem.

joro · #5 09-07-2008, 02:13 PM

I have an extra,do you think this is my problem? anymore diagnosis tools?
Door locks all work.no brake problems,17-18 in pressure at vac pump.
early w123 1980

Chad300tdt · #6 09-07-2008, 02:16 PM

Quote:

Originally Posted by joro

I have an extra,do you think this is my problem? anymore diagnosis tools?
Door locks all work.no brake problems,17-18 in pressure at vac pump.
early w123 1980

If you even have an extra one already, I'd replace it. I thought of the switch being the issue originally due to your comment about it being difficult to shutdown even at the lever.

compress ignite · #7 09-07-2008, 02:19 PM

'Could have the Vacuum Shutoff Valve Lever installed incorrectly(blocking the
manual shutoff lever from closing fuel delivery).
They are two separate actions (that meet at the vacuum shutoff's "Pull Rod")
The manual shutoff lever ("STOP") is there in case the vacuum diaphragm ruptures.
I'd look into that right promptly!
('cause right now your two options are BIG rag in the turbo OR jerking the
fuel line from in between the secondary fuel filter and the Injection Pump +
praying it shuts down quick enough.)

pizzachef · #8 09-07-2008, 02:21 PM

Disconnect the door lock system and then try to shut the car off. If you're losing vacuum while the car is sitting, one of the door actuators or rubber connectors probably has a hole in it.

You can disconnect the central locking system pretty easily...there is a yellow vacuum line coming out of a connector in front of the brake booster. Pull that yellow line out and stick a golf tee in its place. Then start the car, let it run a minute, and shut it off.

That'll at least rule out the shutoff switch. Maybe.

EDIT
I just re-read your first post and saw you even had trouble shutting down with the stop lever. The other suggestions here may be more meaningful.

pizzachef · #9 09-07-2008, 02:26 PM

Quote:

Originally Posted by compress ignite

('cause right now your two options are BIG rag in the turbo OR jerking the
fuel line from in between the secondary fuel filter and the Injection Pump +
praying it shuts down quick enough.)

CO2 fire extinguisher into the air intake. Should work pretty quickly, although I've never tested it.

joro · #10 09-07-2008, 02:45 PM

pump diapragm is new,its a non turbo.

toomany MBZ · #11 09-07-2008, 06:46 PM

I'll agree with compress ignite, make sure the shut off lever is unobstructed. That is a red flag, it should stop the engine when you press the lever.

joro · #12 09-07-2008, 07:05 PM

You guys are right,i just adjusted the valves and it seems like everytime i adjust valves and put cover back on i always always make some trouble by messing up how linkage goes and such,but if i did wouldnt car still be able to shut off by using the key? Assuming pump is good.
thanx