Engine still running for 5-10 seconds after turn off ignition.
 

I have a 93 300SD w/603 engine. Engine still running for a few second (5 to 10 seconds) after turn key off. I don't know if can be the IP, I did check the brown hose for the vacum. Hope to hear any body experiences and what solutions to apply. Thank you guys.:cool:

Rear A/C vent cold at all times
 

I have and 92 300SD and notice that vent for the back seat does run cold every time that I turn on the ACU, even when I run the defrozer. Please advice. :cool:

Put a mightvac to the SOA (shut off actuator) see if that shuts the car down (your stop lever should drop and stay down) if it dosnt, your actuator is shot and you need a new one, I'm sure it's simple to chage, they recently replaced mine.

Ditto above.

You have a vacuum leak, somewhere between the SOA and vacuum pump.

Yup. Do the Mit Vac check. My actuator failed too and had to install a new one.

I agree with the vacuum leak theory. The actuator is not that hard to replace - do a search on the site for shut off valve.
Just be careful to hook it up properly so it shuts off the engine and does not prevent it from being shut down.

Also the rear vent will always blow cold. It is for outside air.

The 1992-95 300SD (S350D) has an odd system for the vacuum shutoff.

Instead of direct vacuum like most other MB's, it used a relay that energized a switch-over valve that allowed vacuum to pull the shut-off diaphragm closed.

Had a few cars that that relay didn't send signal quickly to vacuum valve.

Testing is STILL done with a vacuum guage teed into the brown line at the pump.

My 124 will blow warm air for the rear seat foot warmer vent...the one underneath the front seats.

http://i31.photobucket.com/albums/c3...irPlenum-1.jpg

relay location?
 

Where should I look for the relay? Do I hook up vacuuum gauge at the hose or at the shut off valve?

a/c rear vent cold air at altimes
 

The cold air is comming out from the center rear console. I do need to check the bottom vents. Nice drawing by the way. thanks

The W140 chassis allows only for COLD air from the console vent.
But as all other MB's have vents under the seats for heat.

Connect vacuum gauge "T" at vacuum shut-off valve on injection pump

cold air at rear vent
 

Thank you for the valuable information. Ok, the "T" will be and adaptor to control the air flow? or just to test? Thank you.

I'm pretty sure neither my w126es (2) nor my w123 have any heat coming under the seats. I've never seen the vents, but maybe I was looking the wrong place. Certainly no evidence of warm air back there; just the always-cold outside air source in the center.

The vacuum stop actuator is a well known weakness. I had to replace mine after only 300.000 miles :rolleyes:

This will affect the engines ability to stop, but not the heating system.

Try sucking on the vacuume line to the actuator to find out if it is leaking. Easy job to repair.

Not sure if this one is the problem, but it might be worth checking it.

1. new unit.
2. old unit.
10. new unit in place.