300SDL key switch access - PeachParts Mercedes-Benz Forum

WANT '71 280SEL · #1 02-22-2005, 09:49 PM

I have narrowed my no start problem to the vacuum portion of the key switch. How do I remove the switch? I've read how to remove the cylinder, but what about the rest? I have the under panel off now since I just resoldered the CC amp and haven't put it all back together yet.

As usual, your help is most kindly appreciated.

Thanks
David

WANT '71 280SEL · #2 02-23-2005, 04:14 PM

Bueler, Bueler...

Thanks
David

Johnhef · #3 02-23-2005, 07:54 PM

well, when you can access it, the key will have to be in position 2 to remove the electrical plug at the rear of the ignition. once thats out, with the key in the same position, push in the pin to the left of the tumbler on the shaft and pull the steering lock piece out of the column. I think theres a small bolt somewhere among all this that had to be removed too, should be easily visible if I recall.

WANT '71 280SEL · #4 02-23-2005, 11:43 PM

What part should I order to replace the vacuum element of the switch? I think there are around 4 different pieces listed on fastlane regarding the key switch.

Thanks
David

Johnhef · #5 02-23-2005, 11:47 PM

So it is definitly bad then? it supplies vacuum no matter what position of the key?

WANT '71 280SEL · #6 02-24-2005, 12:04 AM

When the key is turned off, it apples vacuum as it should. The problem is, once the key is turned on, it doesn't always turn off the vacuum. I looked under diesel injection I think and found the shut-off valve that's attached to the key switch. So, I need to order this shut-off valve and the electrical portion and my key switch should be good to go. A member here sent me the PDF from the 126 manual which should help greatly, I just hope I can make sense of things once I'm in there. Does anyone know if it's possible to replace the electrical portion and the shut-off valve while the whole lock assembly is in the car? That lock thing is huge and I can tell it would be a pain if I have to remove the steering wheel and all other surrounding pieces.

Thanks
David

Johnhef · #7 02-24-2005, 07:16 AM

Quote:

Originally Posted by WANT '71 280SEL

Does anyone know if it's possible to replace the electrical portion and the shut-off valve while the whole lock assembly is in the car? That lock thing is huge and I can tell it would be a pain if I have to remove the steering wheel and all other surrounding pieces.

Thanks
David

That, I dont know if its possible or not. Just before you start pulling it out to replace, or ordering parts, you can definitly feel vacuum on the line to the injection pump with the key on, correct?

The vacuum switch is a small, maybe an inch long or so, metal piece held in by two small screws, with the two vacuum lines attached to it. There is also, for the lack of the correct term, a "plastic disc" under the electrical part of the ignition (mine was blue) that turns with the key to press in the tab on the vacuum switch. Its possible that piece is broken, only way to tell is to take it all apart, you can't see it with everything still assembled.

WANT '71 280SEL · #8 02-24-2005, 04:05 PM

John, I definitely feel vacuum at the hose with the engine off. I ordered the key switch vacuum shut-off valve and electrical part.

Thanks
David

Johnhef · #9 02-24-2005, 05:42 PM

well david, when you get it out, let me know what you find, good luck.

one more thing, great username! i miss my 69 280SE

I'll get another someday...

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