I was having a pretty common problem to my car, a 79 240d W123, which was my shut off valve wasn't shutting off, and the engine would continue to run after I turned off the ignition. Using the forums here I deduced that this was a vacuum issue, and that the shut off valve needed to be replaced and I took it to a shop that was very highly rated on Yelp as mercedes experts for San Francisco. They replaced the valve and also my ignition switch, the bill was $800.00 which I thought was crazy.

The thing is my car still runs for a little while after I turn off the ignition, but now my locks don't work, and I also have water coming in on the drivers side footwell and I didn't have these other problems before. Before I take it back to the shop does anyone have any advice about A. How much is reasonable for this kind of repair, and B. Things that I can troubleshoot myself that may fix the problem? Any advice would help!

 

Need more specfics. Did the shop replace the Ignition Switch or the Ignition Tumbler (the part you stick your Key in). And what type of problems were you having there.
If the shop installed either of the above it is up to them to fix it.

The Engine being slow to shut down is not a problem to approch by replacing parts that you think might be the cause.
You check the Vacuum as it comes from the Vacuum Pump to see if the Pump is good.

You Disconnect the Vacuum that goes to the Climate Control System (the tubings are color coded) and the Door locks and Plug the connectors on the Vacuum Source side. If you shutoff works you have a Vacuum Leak in one of those systems.

While the Engine is runing you disconnect the Vacuum Tubing from the Shutoff Valve on the Fuel Injection Pump. If there is Oil Engine Oil in the line that is a sign that the Shut Off Valve is on the way out and has at least a small leak. But, you also hook up a hand pumped Vacuum tester (generically called a Mighty Vac) and pump it to cause vacuum and see if it shuts off the Engine. Or, you can simply connect a piece of Vacuum Hose to the Vacuum Shutoff and suck on the end of it to see if it shuts off.

If all of the above is OK you can start to suspect the other Vacuum Switch that is located on the Steeringwheel Lock Housing. It could be the Hose ends there are cracked and leaking Vacuum or the Vacuum Switch there is no good (the switch there cost about $30+shipping).

I cannot help with a regular leak.
If it is Coolant Leaking inside of the car you have a leak in your Heating System.

 

They replaced the vacuum switch on the steering wheel lock housing, but they called it the "ignition manifold". There was oil in the vacuum lines, and the tubing was pretty gummy, so I had a pretty good idea that the diaphram on the shut off valve was shot, so I wasn't surprised that it needed to be replaced... $800 seemed really really steep though. I took it to a shop because I don't really have a good place to work on the car, so I'm feeling pretty foolish and burned right now.

My feeling is that when they were working they did something to cause a leak in the doors, because I never had a problem with them before and now I do... The vacuum hoses have been replaced and are tight under the hood, so I'm assuming the leak is on the other side of the firewall. I'm going to block that hose tomorrow and see if the engine shut off at least works properly, I can live with out the vacuum locks for a while until I track down that leak.

Thanks for your response!

 

Keep in mind when the key is turned off it won't be instant like a gas cars were it kills the spark.

 

If you were getting Oil in the Vacuum Lines by the Shutoff it needed to be replaced.

I just did this today to help someone on another forum. I pulled the Vacuum Line off of the Fuel Injection Pump Shutoff Solenoid (Engine running) and connected my Vacuum Gauge to the Vacuum Line. I had my Wife turn off the Ignition Key.
I got 20 inches of Vacuum.

Since my shutoff system is working OK I am thinking that if you are getting less than the 20 inches of Vacuum (assuming your Vacuum Pump is working OK) your shutoff might not work as well and there could be another Vacuum leak somewhere.

On the other fourm I for got to mention that the little white Valves on top of the Valve Cover (under the plastic lid) can also be a source of Vacuum Leaks.

I do not know how picky they are in the City youl live in but, I have seen people do stuff like work on their Car Radio in the City Park. I have also seen people do more then that in the Autozone Parking Lot.

In some Cities people will rent Garage space per day for people to fix their cars.

The old Vacuum System hoses and tubings do not take much stress on them to cause a leak. I changed my Oil and without knowing it broke the nipple off of the main Vacuum Line that goes to the Brake Booster. I found out when I could not shutoff my Engine.
All I did was lean on it when I put the Oil Filter in and out. Fortunately I was able to patch it back together.

So the mechanic could very easily have disturbed something else while doing his work.

The $800 does seem like a litt too much. But, if that included parts they mark up the price on the parts. It is not unknown for places to charge as much as $150 per hour.

 

I think you're right... I think when they put in the new vacuum hose to the door locks they may have disturbed the connector in the door. I'm pretty sure I have it narrowed down to the drivers side door lock, I'll be taking that apart tomorrow and I hope it is the culprit! Thank you!