W209 Poor seat belt tension/retraction

[Coruscator]

Hi guys, yes its me again. :0)

Done a bit of googling because my seat belt is slow to retract when I take it off.
Sometimes it gets trapped in the door when I get out.

Ive seen some vids and articles from a W209 on this but they just mention replacing the mech.

Is it possible to remove the belt from the winder to re-tension the spring on
a W209 as this guy is doing on a different MB?

https://www.youtube.com/watch?v=X4arpjIylwA

I can see that the seat belt mech on a W209 has an SRS device attached.
Should I leave well enough alone or is this do-able?

I'd quite like to wash the belt too as mine is light grey and shows off the dirt
like its on a cat walk! :0)

 

[Coruscator]

Ok, I couldn't wait for someone to reply, so I went ahead and did it anyway.

Getting the panel off in front of the rear drivers side window was straight forward enough.

1. Disconnect battery and wait 15 minutes for the current to disapate.
2. There are 4 torx bolts holding the seatbelt mech in place, remove these.
3. Unplug the green SRS plug from the mech.
4. Remove the torx bolt from fixing point behind the arm which extends to
give you the belt when you close the door. (whats this called again?)
5. Remove the torx bolts which holds the chrome bar in the rear footwell.
6. you will now have the seatbelt and mech free from the car.

Take a break! (I did, phew)

7. Remove the beige/grey plate from the mech
8. You will now have good access to the sprung seatbelt winder.

NOTE: Dont panic if the seat belt will not extend, you will need to wind it back in again a
little and (most important) ensure you hold the mech in an upright position or gravity
will pull a small ratchet type lock into place and it wont extend.

9. Unwind the belt fully. This is where it gets a little tricky. There is a silver
'U' shape clip which holds the end of the seatbelt on the winder.
10. Pull this siver clip away from the winder. There is a shaft inside that the
belt loops around. (see photo) Remove the silver clip from the folded loop
in the end of the belt.
11. You can now pull out the belt from around the shaft inside the mech.
12. MOST IMPORTANT!!! DO NOT LET THE WINDER UNRAVEL ITSELF OR ITS
GOING TO BECOME A MUCH BIGGER JOB THAN IT NEEDS TO BE, OR MAYBE EVEN WORSE!!!
13. You can now add tension to the winder by rotating the winder against
the push of the spring, I was able to get 3 full rotations before it felt like enough.
14. INSERT SOMETHING INTO THE WINDER (I USED THE SAME TOOL I MADE
TO REMOVE THE CLOCKS FROM MY DASHBOARD) SO YOU CAN SET IT ASIDE.
15. Find some very strong nylon string or flexible steel cable. I used nylon.
16. Thread it through the loop in the end of the seat belt, then tie it off.
17. Pass the end of the nylon into the winder and around the shaft within.
18. Pull the nylon through so it threads the seat belt back onto the winder.
19. Once you have it back through you can re-fit the silver clip which holds
the belt on the winder.
19. Cut the nylon string away and you should now have a belt with enough tension
to fully retract when fitted.
20. Refit everything back into the car. :0)


I hope this helps. :0)

 

[Coruscator]

Worth mentioning that I also soaked my belt in hot water with some non-bio
clothes washing liquid (or powder) for about an hour, then did the same with
just hot water to rinse the suds out and then let it dry in the sun.

My belt was quite dirty and I'd read that a dirty belt will aslo develop more
friction as it tries to wind itself back in. Just the oils in your skin on your hands
over the years will be enough to increase the friction.

OMG I think I should have tried just washing the belt first. Ha.

Went out for a spin and when I got back and removed my belt it almost took
my ear off!

 

[dbclk]

Hi Coruscator,

Thanks for taking the time to post this info. I have a 2004 C209 clk 270 cdi so your info/description is a very close match.

I'm obviously less technically able than you are, so my plan is to remove the seat belt and send it off for repair (I think that the spring mechanism is broken).

I haven't quite figured out how to remove the bottom rear panel yet, but should be able to do that. I don't have a torx bit that fits so will need to find out what size the bit is and purchase one. I'm not sure whether my car has seat belt pre-tensioners, however my model doesn't appear to have an airbag in the rear; is this why you disconnected the battery?

Your post is from 2016, so I realise this is an old thread. If I don't hear from you, the info you provided has already been very useful, so thanks for doing that!

: )

Ok, I couldn't wait for someone to reply, so I went ahead and did it anyway.

Getting the panel off in front of the rear drivers side window was straight forward enough.

1. Disconnect battery and wait 15 minutes for the current to disapate.
2. There are 4 torx bolts holding the seatbelt mech in place, remove these.
3. Unplug the green SRS plug from the mech.
4. Remove the torx bolt from fixing point behind the arm which extends to
give you the belt when you close the door. (whats this called again?)
5. Remove the torx bolts which holds the chrome bar in the rear footwell.
6. you will now have the seatbelt and mech free from the car.

Take a break! (I did, phew)

I hope this helps. :0)

 

[Eddy77]

If your belts were dirty, this was the problem. I had dirty belts and a simple clean with non bio sorted the retraction mechanism out!

 

[dbclk]

If your belts were dirty, this was the problem. I had dirty belts and a simple clean with non bio sorted the retraction mechanism out!

Hi Eddy, thanks for your input. I agree that cleaning the belt is the first thing to try. In this case a dirty belt isn't the problem (I cleaned the belt). I'm pretty sure that the mechanism (spring) needs replace as the belt doesn't rewind at all.

I've ordered some Torx bits that should fit, and will make a call on whether to proceed when they arrive.

Thanks again!

 

[Trickythemerc]

My drivers side belt was slow to retract so I fully extended it and gave the belt a good spray with dry silicone lube, cured it within minutes.

 

[dbclk]

My drivers side belt was slow to retract so I fully extended it and gave the belt a good spray with dry silicone lube, cured it within minutes.

Thanks Tricky, that sounds like a good thing to try early on. In my case, I'm passed the point of an easy fix and know that the problem I have needs a technical solution/intervention.
All the best!

 

[Ledbelly]

I had the same problem with my W209 but was putting off dismantling the trim etc to fix it. I followed Tricky's advice with the dry silicone and it has worked perfectly.
Nice one Trickythemerc !!!

 

[dbclk]

I had the same problem with my W209 but was putting off dismantling the trim etc to fix it. I followed Tricky's advice with the dry silicone and it has worked perfectly.
Nice one Trickythemerc !!!

Thanks Ledbelly - that seems like the first option to try. Will probably remove the part and send off for repair. Cheers!