W124 notes on stuck ignition and bad shut-off valve

[aersloat]

I haven't been doing much work on the car the past year since I have been renovating our house, but my hand was forced this weekend.

A few weeks ago my shut-off valve died and I have had to open the hood and manually kill the engine. Obviously this is a pain especially now that we are in the pouring rain season in Portland. I have been living with it though.

On Wednesday I had a little trouble turning the key in the ignition after picking up the kids at daycare. Thursday morning, with the rain pouring down, the key wouldn't turn at all and I had to transfer both kids and their car seats to the backup car.

I went to MB of Wilsonville with my title and ordered a new lock cylinder with key and one extra key. The parts guy helpfully added "I hope you can get that key turned." The total cost was about $120. They don't discount anything. He said it would be there the next day. I didn't believe him, but sure enough 24 hours later it had arrived from Ft Worth.

I played with the existing cylinder trying to get the key turned. The trick for me, as has been the case with others, was vibration. I used my Fein Multimaster with a soft sanding pad attached. I worked on the key and eventually it turned.

I used every wire and clothes hanger variety I could find in the house. Don't bother... just go to you local bike repair and get two 2mm spokes. Cost me $1 a piece. The lock and surround popped right out with the spokes (I did bevel the ends). The existing cylinder had broken inside and there were some metal chips in there. There were also some brass filings although the two keys I have are factory steel keys.

Getting the new cylinder in was a bit tricky just to align correctly, but when you do it just snaps right in.

Since I was doing work on the car I decided to fix the shut-off at the same time. Diagnosis: put a mightyvac on the shutoff valve and it wouldn't hold 5 psi-- enough to wiggle the level but not fully actuate it. I also put the mityvac on the business end of the hose and when the key was turned "off" there was in excess of 25 psi of vacuum delivered on the line, so it was definitely the shutoff valve.

Fortunately I have a spare injection pump and it had a shut-off. That shut-off was an updated part number. I put the mightvac on it and it held a vacuum no problem.

So, the shutoff valve will come out w/o pulling the manifold. You have to pull the electrical plug that is next to it and you have to unscrew the ALDA so that it can be moved over. The electrical plug interferes with the valve itself while I had to move the ALDA to get to the back bolt. To get to the ALDA I pull the windshield washer reservoir. The back bolt is a bit tricky. Once the bolts and the clips are released the valve is pretty easy to get out. My spare had a good o-ring so it went right in. You have to angle it in from the side so the groove in the stop lever will engage the plunge arm on the valve. Once everything was tightened back up I put the mightvac on the valve and it plunged the stop lever. Hooked up all the vacuum lines and tried it out. The ignition kills immediately now. I guess the old valve was pretty worn out. It would always stop, but was never authoritative.

In conclusion, you might not get much warning at all that your cylinder is about to croak. I didn't, and not being able to turn that key is a bad bad feeling.

Replacing the shutoff valve is only about 1/2 hour if you have previously removed the ALDA with the manifold in place. I have two open ended wrenches that I know fit so it was only few minutes to loosen the ALDA enough to get it moved over.