Door check strap?
 

My passenger's side door on the 300D will not open to the second stop. I noticed earlier today at a restaurant that when it opened, it would make a big popping noise with some resistance to it as the door opened to the second stop. Later at the truck stop, it would not open to the second stop at all, I tried to open it more, but I don't want to force it, it felt frozen at the first stop, and from what I've read, this means that my check strap has gone out. Is my assumption right?
-Joe

Probably. They are not terribly expensive and the biggest pain about replacing them is that you have to remove the door panel. Really not a big job. Less than an hour last one I did.

Yep, it's the check strap.

When the spring fractures, the ball can't properly move in the groove, sometimes making the door impossible to open.

I had to force one of the rear doors on the SDL. Thankfully, I did not break the mounting lug off the door frame.

Make sure you read up on the procedures for removing the door panel. It has plastic tabs that are very fragile. If you don't carefully lift the panel straight upwards, you break the tabs off the panel. You can't get them back. :mad:

If you break the tabs off the panel, you just have to get some good gorilla glue and glue them back...keeping the door shut for 12 hours will act as a clamp.

I think it is inevitable the the plastic tabs will separate from the panel... just lift up...if you pull and break the plastic tabs, you will have to get new ones.

The W123 has the pull-out clip type door panels that most other cars have these days. The clips can be replaced if they break.

Question about strap, mine is working but it is making a little noise when you extend the door, can you lubricate the check strap?

Brian, I believe you mean the tabs that break off are on the front door pockets, on 123's that is, and they lift up, o/w the small plastic pop-ins around the rest of the door panel pull out away from the door, not up. They are replaceable and are cheap if they get broken, or you can glue them in if they pull out of the composite material. The rear doors are a piece of cake because you don't have the pockets to worry about.
One thing that can frustrate you when you go to install the door catch is getting the arm out, it has to be pulled out before you install the door catch (no I never did that stunt :P ).
To get that arm out I have seen people clamp the body in a vise and yank on the arm. That is fine if you have a vise tied to a heavy work bench otherwise the whole bench can (and will) move as you yank.
I take a coathanger wire and run it thru the hole in the arm where the pin goes and run that over a strong overhead joist, tree limb or whatever and tie the wire real tight at the junction. Then I put my full weight on the body of the door catch and yank straight down and the arm pops out. It can be a bear!

Reid, on the W126, the tabs are at the very top of the door panel. The trim rests on these tabs. The extend vertically downward and contact the steel door frame. They are very fragile and can easily be broken. They cannot be replaced.

I agree. Getting the arm out of the body is no fun. I usually use a couple of pairs of channel locks. If you have the grip, you probably have sufficient arm strength.

You can, but you need to remove it from the door to do it properly.

Both the rear ones on the SDL are bad and the driver side on the SD... at least it doesn't shut on your shin when you drive it. :rolleyes:

I looked at one at the boneyard, it's three bolts, an e-clip, and maybe an hour of your time. At least it's inexpensive and decently easy to replace. :)

On mine the ball bearings came out of the grooves. I took the pieces out of the door and after several attempts with a vise I managed to get everything back together. The reason I say several attempts is that the spring is a strong one when compressed between the thickness of the ball bearings. The suckers flew out of the vice like bullets. After I got it together I greased it substantially with Lubri-Plate wheel bearing grease. It is now smooth, quiet, and you can feel the detents when you open the door.