85 300td wagon, seat belt locks up about halfway
 

Here's an interesting one. On my 85 300td wagon, the seat belt mechanism locks up about halfway when I pull it from the door frame. It locks up and I cannot pull it further and it will not retract. Stops when its about at mid chest length. I usually remember to put my seat belt on after about a block from home (I know, bad habit) and the only way to get it to work properly (rarely) is pull over and jiggle the heck out of it to allow it to retract and then retry or.... towards the end of my commute I go over a pretty steep bridge and the seat belt releases its lock by itself on the downward slope of the bridge. Strange but true :)

I have yet to go into the mechanism to search for clues. Any first hand experience with this type of issue?

With a recent change in Florida law, where LEO's can pull you over for just not having a seatbelt on, I find it troubling to have an "sometimes" inoperable seat belt assembly :(

I'd get it replaced ASAP.

LEO will not care if it's working or not. You get the ticket.

Thanks :) Any insight on what might be the issue?

If it makes you feel any better, my driver's side does the same thing. Noticed that if I just leave it alone for a while, it will self-heal. Otherwise, I have to pull the cover off and fiddle with the mechanism.
This is one of those things I've just put off, but I really need/want to replace it.

Seems like I've heard though that these seat belt mechanisms have pyro devices built into them to pull very quick tension on the belt in the event of a crash. Thinking this is gonna mean $$ to replace. Can anyone confirm this?

I would just open the pillar cover and with a pen/ scewdriver push the belt back from the roll, it does usually do the trick as it will roll back itself once started :)

My w123 does this when it is really cold outside. If I leave it alone the belt will eventually come back in on itself.

I could have sworn I saw a thread on this site detailing how to fix it. Maybe by lubricating the gear mechanisms in the pillar.

My TD used to do it and like you I'd have to jiggle it. Problem went away and hasn't come back in about 3 years.

WD-40 on the mechanism. Be careful not to get it on the belt itself.

The seat best is a safety device, I don`t think it is something to take lightly. the drivers side gets the most use, and after 2 - 300,000 miles they do wear out.

I think it was the 85 yr model that the pyro devise was used. do not try to take the unit apart. for safety reasons.

our 85 had this problem about 10 yrs ago. couldn`t get it out, or to retract. since I did want it to do it`s job if the situation came up. so I sucked it up and bought a new belt. been working just fine since.

Your life, do what you want.

Charlie

Out of curiosity, approx how many arms/legs are they getting for one of the pyro equipped seat belts?

I've never had the belts on a Benz apart so this may not appy at all... Some other makes have a little counterweight that runs the ratchet on the belt to stop the belt during hard decelleration, like in a crash. If the Benz has something similar that could be the thing that is giving the trouble. Your description of the belt freeing up on a bridge may point to something like that...