Spinning Number Plate Screws - HOW TO fix

Page may contain affiliate links. Please see terms for details.

Eddy77

Active Member
SUPPORTER
Joined
Jan 31, 2016
Messages
978
Location
Fleet, Hampshire
Car
2008 CLK 350 Sport Cab and 2021 BMW 520i M Sport Saloon
Symptom:

The number plate screws for your rear plate spin and spin. You can’t undo them because the thread into which they screw is spinning behind the boot panel.

Reason for Problem:

MB, in their infinite wisdom, use steel screws to secure the plates. But the threads into which the screws are fixed are made from aluminium. Over time the steel screw and the aluminium thread weld together and then when you try and undo the screw, the thread becomes detached behind the boot panel and spins with the screw. Rather like having a bolt on the rear of the boot panel and it spinning freely when you turn the screw from the front.

How to Fix It:

This happened to me on my 209 CLK cabrio. But it is a common fault on many MBs. Firstly, there is no point hoping that by pulling, spinning or applying any kind of force from the outside that they will shift. All you risk doing is slipping with your screwdriver and gouging the paintwork. So stop right now!!!

You need to remove the interior boot panel. On my W209 2008 CLK, this was quite simple. The inside of the boot lid is lined with carpet panelling held in place by those commonly used black plastic round press through clips. Get the claw from a small claw hammer under each clip and gently lever each one away. I managed to remove all of mine without damaging the clips and they could all be refitted. If you do damage a clip, Merc can supply them I’m sure.

On the CLK you need to also remove the warning triangle and the plastic holder for it. The warning triangle holder clips in. You kind of jimmy it out and slide it to one side at the same time. Hard to explain but a bit of careful levering and sliding and you’ll find it pops out. It is not held in by screws – just clips and slides into position.

Finally on the CLK loosen off the hex bolts around the boot handle and boot catch. You don’t need to remove the whole handle – just loosen enough to free the carpet panel from under it.

Remove the carpet panel carefully. Watch out for wires – your GPS antenna and other gubbins is all in close proximity so careful not to dislodge anything.

Once removed you should be able to see the threads into which the number plate screws locate. They look like aluminium “rawplugs” and there are four of them. Get a sturdy pair of pliers and grip the thread “plugs” which are giving the issue. Access is a bit tight so watch your knuckles!

From the other side unscrew the steel screw. This is a two person job. Get someone to grip the plug thread on the inside tightly whilst you turn the screw from the outside. It will be VERY tough to break the corrosion seal so a steady hand and a good screwdriver is required.

I packed an old towel around the number plate to protect my paintwork should I slip with the driver whilst trying to undo the screw. I did slip a couple of times and am glad I had a towel there to protect the paint.

Eventually you should be able to get the screws out.

If the threads really are welded to the screw and won’t unscrew as suggested above you have two options.

Either snap away the number plate from the outside so that you can see some screw thread from the outside. Then carefully use a junior hacksaw to cut the screw just below the head and remove the whole screw and thread from inside. Or, if you can get access, cut them off from the inside with an angle grinder or cutting tool.

If that seems too horrific, snap the old number plate off, leave the old screws in situ and fit a new number plate holder over the old screws using self adhesive pads. A bit of a bodge, but I think this would work OK if you needed to.

Once done, reassemble, sit back and marvel how a job which you expected to take 10 minutes ended up taking two hours!

This guide is specific to the CLK, but I strongly suspect all MB’s are assembled in a similar way and the same principles apply to all models.
 
On my S202, the answer was to place a 7mm socket over the tubular nut, remove the screw and then drill out the tubular nut. Treat the area around the nut which will have bubbled up and corroded electrolytically with a drop of bondaprimer around the hexagonal hole and place a grommet in the hole. Fit the new nuts and bolts. Seal with RTV.
 
Another option - drill out the screwhead, remove the number plate then drill out the old retaining threads.

Install a replacement thread using a blind rivet nut and a riveting gun. Avilable in sizes from about M3 to M8. They cost peanuts, job done in minutes with no disassembly needed.


.
 
The nut in question is fitted in with a rivnut tool Reason is that 90%of boot lids have no room at the rear to get the nut on.The part is a mercedes part only and you can get them from mercedes dealers .All i can see have round shoulders on them on ebay .But the mercedes ones are hexigon in shape so is the hole they go in to in the boot lid. I had the same problem, and doing mine i snaped a drill off inside, as the screws are chrome plated brass. I have a few of them but without a size its not possible to say what size they are. You can fit them in with nuts and bolt to squeeze them up in the boot lid .. MB is the best place and only place i know you will get them from.
 
Aluminium and steel, galvanic incompatability. The bane of my life in my previous job, I can't tell you how many screws I've drilled out over the years.

My recommendation to anyone facing this problem, before you start, invest in a can of this stuff:

https://www.amazon.co.uk/d/Automotive/Tri-Flow-TFL200-Lubricating-Sprays-Oils/B003615XMU

It's not cheap but how much do you value your time? A quick squirt of this (it doesn't need a lot), wait 5 minutes then marvel as the screw simply comes out. It also does anything WD40 will do only better, well worth having a can in the cupboard.

Cheers,

Gaz
https://www.amazon.co.uk/d/Automotive/Tri-Flow-TFL200-Lubricating-Sprays-Oils/B003615XMU
 
Just had this issue on my W212 E class.

This thread was very useful. It did not take long to sort. About 45min. It was a single person job.

Lift the boot up. I had to remove the moulded plastic fitting just behind the boot lip. This is the fitting containing the boot lamp and "boot close button". There were 3 plastic "push fit" fittings which I popped out with a screwdriver (gently to allow reuse).

This is all the access required. I did not remove the carpet or take any other of the other many push fit fittings out. To remove the fitting I just had to pop out the electrical connectors for the lamp and boot button.

You can peek through the gap and see the inside of the number plate fittings.

I had a set of mole grip pliers from screwfix for 7.99 (Self Grip Pliers Set 3 Piece | Pliers & Cutters | Screwfix.com)

I used the middle size pliers to grip the inside. Then used the larger grip plier on the outside. There was plenty of WD40 soaked in. Very gently twist the outer grip while holding the inner one still. The screw should gently start moving. I got 3 out with no problems. The 4th sheered. Luckily I was able to fit my numberplate surround with 3 screws.

Overall very happy with the look.
 
I had the same problem yesterday whilst removing the number plate to refit boot lid trim during fitting of RVC.

In the end, I left the stuck screw in place and enlarged the hole around the head and removed the holder. The screw was firmly stuck, after a couple of turns. Could not get it to budge, despite plenty of penetrating fluid, grips and cursing!

I refitted the holder with just the 3 screws with the stuck screw not tightened.
 
Had the same problem, i cut the screw heads off with an angle grinder and re-drilled and fixed back on with self tapping screws. So no need to go into the boot.
 
Just a quick point. The black plastic rivets that hold the carpet trim, prise out the insert first (the smaller round centre piece) with a flat head screwdriver then do the same with the retainer, it'll come out much easier and you won't risk snapping them.
 
Hello,

I have a w204 c class and my number plate is coming off as was drilled with self tappers on the boot lead. Do you know the part number for the the inserts on the original 4 holes?

Alex
 

Attachments

  • IMG_1240.jpeg
    IMG_1240.jpeg
    2 MB · Views: 5
For starters these securing nuts are put in with a rivnut tool .The rivnuts and setting tool come in a set from Ebay but the rivnuts are not the same as Mercedes ones . Also the rivnuts are not all the same size , it is all to do with your model , because over the years Mercedes used smaller ones .. See my post above .These damaged ones can be a bugger to remove, even with a drill . The drill tends to ride off .Inmy case it broke off inside .Its still like it today .Read this ,Rear license plate problem
 
Or just use double sided 3m tape like the rest of the car industry and no longer have to drive around in a car with four ugly bolts sticking through your number plate. First think I've done on every Merc my wife and I have owned! YMMV....of course.
 
Or just use double sided 3m tape like the rest of the car industry and no longer have to drive around in a car with four ugly bolts sticking through your number plate. First think I've done on every Merc my wife and I have owned! YMMV....of course.
Ok I am happy to do this but should I not worry about sealing the holes first?
 
Ok thanks I saw the he metal inserts. Do you know if I can use any plastic ones like these ones? After us it a frame to put the number plate or I have to drill for holes on the number plate? Also one last question how do I fill the hole for the self tappers the the garage made?https://www.amazon.co.uk/gp/aw/d/B009HOQK9U/ref=ox_sc_act_image_2?smid=A3RUI5R3BC1F74&psc=1
Yes that nylon plugScreenshot 2023-05-22 at 09-48-47 fir tree clips - Google Search.jpeg on Amazon would do the same job . If the holes are out of sight and if there is clearance put a screw back in the hole or a fir tree bung like these. With a dab of grease before pushing them in .Most plate holders i have had will have all the locations to screw in it without drilling it .
 
Do they make small sizes of dry wall ? ,Thats another good idea . But you can buy rivnut kit with all sizes of rivnuts in . Mercedes original inserts and screws are the best way to go, and then use a nut and washers to press them in the lid .Lub well or they with corode . Rivnuts are round to fit the hole But Mercedes ones are six sided flats on them to hold in the boot lid hole the same flats in the boot lid in case the screw rust up it stops them turning .
 

Users who are viewing this thread

Back
Top Bottom