Brittle Plastic and What to Do About it
 

I'm sure I don't need to inform anyone who has owned these W124/W123 chassis vehicles that it is nearly IMPOSSIBLE to remove almost anything plastic without having said part or piece simply crumble in your hand. Case in point: in an attempt to replace a third brake light bulb, on my 260E, the back simply crumbled in my hand. Getting to the point...


What are others here doing regarding replacement of these things? I bought a used one off eBay but in spite of my handling it with utmost caution I still ended up popping both tabs off the back trying to remove it (prior to placing in rear window) to replace the bulb that came with it!!! Sooooo, what's a fellow to do shy of ordeing a 'new' Genuine Mercedes brand from dealer - and that's IF they can find it in their stock :mad:


Suggestions, thoughts, experiences? Thanks


Dale

Evenly working of a large assembly helps as does a warm enviroment. PAst that not much helps.

Always check factory parts pricing, sometimes stuff is priced lower than you would expect.

Good advice for certain! Thanks...

some plastic parts can be painted over in a different (or the same) tint using SEM Color Tint paint. I've done that quite successfully on a few things over the years.
If for example you found a cover that wasn't all crispy and baked by the sun that was the wrong color and you are willing to invest in a $15 can of paint that might be a solution.

If you think a Mercedes is bad, try a Volvo 700 series. I've never seen such brittle plastic. On my W124, the only brittleness issue I've had was with the 3rd brake light. After trying a couple used units off ebay and finding they all had the same issue, I just attached the cover with a very light bead of silicone caulk. It holds the cover in place and can still be pulled off to change the bulb.

Yep, that's exactly what I did today! Got one from eBay and used a 'vinyl and plastic' spray. No way I could find a deep Brown to match my interior so I just used black. It looks better than the palomino [emoji41]

Dale

I like that idea and will probably do the same.. Thanks

Dale

Try painting several coats Plasti-Dip over it for a base to protect it from being brittle and crumbling, and then do the outer coat the color you want it to match.

These cars also suffer from bio degradable wiring as did Jags in the 80's. I had a 760 and most of the under hood wiring fell apart.

The lighter plastic parts such as the ducting / conduit around the wiring loom in the engine bays of W201s and W124s can sometime respond well to Aerospace303 and perhaps decide to stay around for a little longer if they've been treated...

I have been known to use Minions duct tape in a pinch ;)

Bondic - UV curable plastic bonder
 

Two things:

If the ambient air temps are cooler sometimes warming the part with a heat gun until it's warm to touch can allow the plastic to be pliable enough to not break off the plastic tabs used to hold things together.

On a somewhat related note the large variety of plastics can make it difficult to repair broken and cracked stuff easily. The choice of adhesive is critical for success.

I recently stumbled across Ultra-violet cured plastic bonder called Bondic. Probably won't work for everything, but it does things that no other adhesive can do as easily and solidly. Material on both pieces, position in proper place and apply the UV light to the material; in a couple 3-4 seconds the material has bonded to the parts and also hardened.

Kind of costly but a $10 glue can save all kinds of otherwise very difficult, hard to repair, expensive and hard to find cosmetic trim stuff. One nice thing is the bond/filling cures in seconds. It's also sand-able and paint-able after cure.

I also vouch for a heat gun - whilst working inside a GM 4t65E transmission, its usually said that you need to say a prayer that the harness connectors dont snap where they plug to solenoids.

a heat gun works wonders here and they come out intact. - Same can be used on the interior plastic pieces.

Zip tied mine after looking for a replacement. Not liking that look, I will do what you suggest into the third brake light cover.
Hope I don't break another sun visor clip.

I'm wondering,if you took fiberglass gel mix,and painted,part,would it help.