Key wont turn and not the tumbler's fault - PeachParts Mercedes-Benz Forum

stephenc03 · #1 04-15-2009, 12:54 PM

I have a 81 300SD that originaly was thought to have a bad tumbler. I was able to get it out and replaced it with a new one from merecedes that I ordered. After the new one was installed, i turned the key and it turned over a couple times but by the third time it stuck and I was at square one again. I was able to get it free but I decided not turn it back to the off position just because i know that the tumbler has to come out again regardless. I assume that the REAL problem is the steering lock mechanism that is fualty. What do I do next. Do I have to replace the entire steering column now? Thanks for your help,
-Stephen

marfa300td · #2 04-15-2009, 03:24 PM

I had my steering lock out yesterday trying to track down a vacuum shutoff problem. See this link for a list of related threads:
http://www.peachparts.com/shopforum/diesel-discussion/142232-ignition-cylinder-tumbler-replacement%3B-mixed-diesel-gas.html#post1065596

What I learned on my recent W123 is that the steering lock engages when the key is removed. When the key is re-inserted and turned, it must retract the heavy spring-loaded lock going into the steering column. This operation is allowed by the last few mm of the key that sticks through the cylinder and hits a small spring latch. It's clear how this can wear out.

I called three dealers and was quoted $170, $170 and $198 for the lock (without the cylinder). I think mine might go out soon (next 1-50,000 miles). I made one preemptive tweak to the steering lock before putting it back in with lots of lube. There is a small push-button release that can only be pressed with the key in the "radio" position. I ground this button off on my bench grinder in case the key gets stuck. This button locks into the sleeve in the steering column.

The steering column lock still works, but it removes one small layer of theft deterrent which probably meant more on a $30,000 wagon than a $500 wagon. If the key ever gets stuck, I can pop the whole steering lock out easily without drilling. I'll buy a new steering lock when the funds are available.

Hope this helps.
Rob

LUVMBDiesels · #3 04-15-2009, 03:56 PM

Take a look at the shut off switch attached to the side of the ignition lock. If it is not attached properly, it could bind against the cam that activates the vacuum switch. Try loosening it a bit.

stephenc03 · #4 04-15-2009, 06:43 PM

Quote:

Originally Posted by LUVMBDiesels

Take a look at the shut off switch attached to the side of the ignition lock. If it is not attached properly, it could bind against the cam that activates the vacuum switch. Try loosening it a bit.

Do you have any pictures of what you are talking about? Cant I just disasemble the the steering lock?
-Stephen

LUVMBDiesels · #5 04-15-2009, 07:38 PM

Quote:

Originally Posted by stephenc03

Do you have any pictures of what you are talking about? Cant I just disasemble the the steering lock?
-Stephen

What I am talking about is the shut off switch which is a small cylinder with two vacuum lines connected to it that is attached to the right side of the tumbler cylinder. It is held on with two small nuts. If it moves out of position, it will catch on the cam that activates the shut off function causing the key to stop moving around the number 2 position. In other words you cannot move the key far enough to start the engine.

Take out the instrument panel and feel around the key switch (Ignition cylinder) You should find what I am talking about. If you loosen the nuts and the key moves all the way, you have your culprit. It is easier than dealing with the steering lock.

stephenc03 · #6 04-15-2009, 09:08 PM

The key has full range of motion from the second position to the start function. When you turn it counter clockwise all the way it wont turn back. It turns through posion two
-Stephen

marfa300td · #7 04-15-2009, 09:30 PM

Just for clarification, what are you calling position 2? You are referring to the position where the glow plugs come on, correct?

You need to get the key back to position 1 (radio on) so that you can remove the cylinder without surgery. I don't believe that this has anything to do with the steering lock. All that happens between position 0 and position 1.

I've read here about using small palm sanders or orbital sanders in contact with the key and/or cylinder to help vibrate things, though I've never tried it. I'd try squirting some WD40 in there. Then take a short dowel and hold one end on the cylinder and press the sander (without sandpaper) on the other end and then jiggle the key while it is vibrating. Get it to position 1 and STOP to remove the cylinder.

LUVMBDiesels · #8 04-15-2009, 09:37 PM

Quote:

Originally Posted by stephenc03

The key has full range of motion from the second position to the start function. When you turn it counter clockwise all the way it wont turn back. It turns through posion two
-Stephen

OK, not the vacuum switch then. Sorry

123Guy · #9 04-15-2009, 10:02 PM

Cut your steering wheel full right or left before you turn off the ignition and remove the key, and whenever you park - the steering lock will not engage when the wheels are full right or left. If that fixes the problem, you know that the problem is the steering column lock.

3lpuller · #10 06-26-2009, 04:45 AM

the ignition key in my '82 w123 (240d) failed to work. i took dieselgiant.com advice (thank you!!!) on grinding down the pin potruding into the steering column. regardless the key still did not work! i bypassed the system by removing the vacuum lines and plugging them before starting...
glowplugs don't work but a squirt of WD40 does it everytime... I just short connectors on starter ad it comes right up
and unplugging the vacuum lines to kill the car!

my question is will continued use in this state cause any damage to the electrical sys or otherwise???

thank you for any input!
john