1981 300SD - it is not the NSS or shifter bushings - PeachParts Mercedes-Benz Forum

tyl604 · #1 05-15-2021, 11:14 AM

The 300SD starter has stopped engaging unless I jump it with two crossed screwdrivers on the right wheelwell plastic box. I have replaced the NSS and also the plastic shifter bushings already so it is not that.

At times I switch the ignition off and on again and it fires up perfectly.

So I am wondering if I need to replace the ignition switch? Is that a difficult project?

Or could it be something else? Moving the shifter back and forth to find a sweet spot (ie bad bushings as a few years ago) does not work so it is definitely not the bushings. I guess.

greazer2b · #2 05-15-2021, 11:54 AM

Quote:

Originally Posted by tyl604

The 300SD starter has stopped engaging unless I jump it with two crossed screwdrivers on the right wheelwell plastic box. I have replaced the NSS and also the plastic shifter bushings already so it is not that.

At times I switch the ignition off and on again and it fires up perfectly.

So I am wondering if I need to replace the ignition switch? Is that a difficult project?

Or could it be something else? Moving the shifter back and forth to find a sweet spot (ie bad bushings as a few years ago) does not work so it is definitely not the bushings. I guess.

I did mine a few years ago and replaced tumbler to while I was in there, I would say the one thing I learned was to park under a tree next time

or do on a cloudy day.
greazer2b

dieselbenz1 · #3 05-15-2021, 04:50 PM

I don't like to assume the last job I had done isn't the problem without at least jumpers out the nss and testing it.

Clemson88 · #4 05-15-2021, 05:03 PM

Quote:

Originally Posted by tyl604

The 300SD starter has stopped engaging unless I jump it with two crossed screwdrivers on the right wheelwell plastic box. I have replaced the NSS and also the plastic shifter bushings already so it is not that.

At times I switch the ignition off and on again and it fires up perfectly.

So I am wondering if I need to replace the ignition switch? Is that a difficult project?

Or could it be something else? Moving the shifter back and forth to find a sweet spot (ie bad bushings as a few years ago) does not work so it is definitely not the bushings. I guess.

I do not believe there is a pictorial in our DYI section but I have seen Youtube videos of Diesel Giant removing ignitions.

greazer2b · #5 05-15-2021, 05:58 PM

Anytime you do something first it’s a challenge but these cars are pretty forgiving and so are the members.
One thing I would say from your pictures is give that engine bay a good cleaning you’d be surprised some the other things that need attention when you do.
And as Christuna said don’t touch the tranny no matter how tempting it is until the engine is right, it’s like when mom said “Stop scratching it it’ll get infected” but you couldn’t help yourself right.

When I did mine I received great help here and some of guys sent me pictures they dug up saying Oh I forgot I had these snap-pies.
It’s a tight spot to work and your gonna which you had that third �� ✋ ✋ but you can always count on the help hear.
I believe when I did it spent $40 for switch and $12 for the lock key.
Keep coming back with questions a pictures this forum never let me down .
greazer2b

Diesel911 · #6 05-15-2021, 07:36 PM

The Ignition Switch is at the bottom of the Steering Colum Lock.

Since your Key Tumbler is working and you can turn it into the proper position to remove the whole steering Colum lock which is held in by one bolt a pin you need to depress you are best off removing the whole thing.

The reason is the innards of the Steering Colum lock need to be inspected. I found mine was broken in 2 places and the Ignition Switch itself also needed replacing (it had a badly burned contact point). At the time I did it a new steering Colum lock came with a new Ignition Switch and a new Vacuum Switch that screws into the steering Colum lock.

tyl604 · #7 05-15-2021, 10:02 PM

I do not believe I have any problem with the steering column lock or the vac switch. It feels more like an electrical contact has just been worn down and if I wiggle it just right it might work one time again. Maybe. For a couple of weeks I would jump it the first time of each day and then it would work fine for the rest of the day; then it just stopped working at all.

Will try to find something on Youtube. So can't I just slide out the ignition switch and slide another in? Not sure as I have no idea what the whole set up looks like - have never been into it.

tyl604 · #8 05-16-2021, 01:28 PM

So I looked at parts in the peachparts section. I see ignition switch and also ignition lock with key. What do you guys think likely I need? Surprised to see it at $40 and $20. Very reasonable.

It looks like a simple and easy changeout or am I dreaming? I am still a little leery about fooling with the steering column lock. Need to pull out my CDs and try to find the section showing the ignition. (Do not like those CDs; very hard to find things.)

paul roberts · #9 05-16-2021, 02:22 PM

Quote:

Originally Posted by tyl604

I do not believe I have any problem with the steering column lock or the vac switch. It feels more like an electrical contact has just been worn down and if I wiggle it just right it might work one time again. Maybe. For a couple of weeks I would jump it the first time of each day and then it would work fine for the rest of the day; then it just stopped working at all.

Will try to find something on Youtube. So can't I just slide out the ignition switch and slide another in? Not sure as I have no idea what the whole set up looks like - have never been into it.

replacing all of the mentioned components is easy as long as the key will turn to the #2 position. Yes. Unplugging the ignition switch is a good idea. After unplugging it, the harness and the plug will be hanging down enough to where you can just plug a new switch in and start with a screwdriver. If it consistently starts, with the new or tester switch, that will be your baby. Replacing the switch with the steering column lock intact is a little tricky since there are three screws that hold it in that you have to unscrew by braille. Much easier if the while column lock is out.

merc lover · #10 05-16-2021, 04:20 PM

IMHO, it is best to replace both the ignition tumbler and steering lock at the same time. You may be in luck, last time I checked, both OEM parts are sitting in Germany waiting for your order. And yes, you will pay a few more $$$$ to buy genuine mercedes benz OEM; in my opinion it is worth the extra money.

Clemson88 · #11 05-16-2021, 04:41 PM

Quote:

Originally Posted by tyl604

So I looked at parts in the peachparts section. I see ignition switch and also ignition lock with key. What do you guys think likely I need? Surprised to see it at $40 and $20. Very reasonable.

It looks like a simple and easy changeout or am I dreaming? I am still a little leery about fooling with the steering column lock. Need to pull out my CDs and try to find the section showing the ignition. (Do not like those CDs; very hard to find things.)

If the key turns then the only thing holding the ignition assembly to the steering column is the strap. I believe a 10mm tool will loosen it and allow the entire ignition including the electrical switch mounted on the 'back,' of the assembly.

Pull the gauge cluster first. You'll have to remove the panel below the steering column which may include the vertical panel in the right side of the driver's footwell. Nope, the horizontal panel below the steering column comes off without removing the vertical panels. My bad.

After that panel below the steering column is out of the way you can lower the entire steering column with the ignition still mounted. I'll loosen the strap holding the ignition before lowering the steering column. You will have to pull the dash toward the rear of the car to allow the ignition to pass behind it.

You won't break anything if you are gentle and pull on the dash just enough to allow the ignition to pass. I am sorry that I don't remember how to separate the electrical switch and the ignition switch body. I think it's just a matter of removing three screws on the back of the electrical switch.

I remember trying to put the switch back on and had some issues with the direction a pin within the switch is oriented. Take note when you get it off to check the alignment of the piece in the center of the switch and how it aligns with the center piece of the body it is removed from.

Yes, I'm aware that I ended a sentence with a preposition. Don't care, got a KKK meeting to attend and need to rush. I'm the Grand Brassiere in the north SC area.

tyl604 · #12 05-16-2021, 10:09 PM

Lots of info guys. Thx.

Diesel911 · #13 05-16-2021, 10:23 PM

"I have replaced the NSS"

When you installed the NSS did you follow the instructions in the manual and use a proper sized drill bit to through the NSS and into the alignment hole on the Transmission to aline it?