Interior crayon smell removed. Here's how.
07-05-2022, 07:33 AM
#1
Newbie
Thread Starter
Interior crayon smell removed. Here's how.
Hi all.
TDLR: It's the foam underneath the floor carpets. I’d originally posted that the smell could be cleaned out, but this method only worked temporarily. In the end I just ripped all the backing foam from the driver and passenger footwell carpets out and replaced with sound deadening material and new foam. Months on the smell is much better and hasn’t returned (so ignore the cleaning advice of my first post).
I've had my 2009 S204 C180K for about 5 months now. Loving it so far, but the "crayon-like" old, slightly musty smell of the interior was bugging me. I don't want to drive around in what smells like an old man's car (not that a C Class estate is a young man's car either!). I had kind of got to the point of just accepting and living with it, but it was bugging me every time I got into the car, so knew I had to do something about it.
After doing lots of research to discover the source, I saw a lot of different theories and misinformation – but also no definitive solution either.
So while my wife was away for a week I decided to investigate myself and found the source.
It is not the same smell as a mouldy AC system, it's not the waxy substance around the centre console, or oil burn-off from the engine and it's not the floor mats... it is 100% the foam padding/insulation on the underside of the floor carpets. Other people have discovered this too, but it's buried within so much misinformation and incorrect theories that I thought it worth definitively answering and providing what worked for me to remove it. 2 weeks have gone since I treated and reinstalled the carpets and the smell has yet to return.
I'd identified that the smell was coming from the foam (literally by going around the interior sniffing and pulling things apart). I can understand why people think it's the wax substance or the carpets themselves as the smell obviously penetrates and rubs off onto other things nearby. Once you lift the driver and passenger floor carpets and smell the foam however, there's no mistaking that this is the source. Whether it's the glue that sticks the foam to the back of the carpet and seeps in, or just the foam deteriorating over time – it's the foam itself that holds onto the smell. I assume that this foam is used throughout the car, however (in my car at least), the smell was most prevalent in the driver and front passenger footwells, and treating these alone seems to have eradicated it. I've seen people in Thailand post about completely removing the foam and replacing with cut up yoga mats, but this seemed a bit too extreme for me. I've also seen people re-order the same pieces of carpet, only to find that the new pieces smell exactly the same.
Luckily, getting access to the foam and removing the carpet flooring is a fairly straight-forward job and largely the same process on both sides.
Things you will need:
– Flat head screwdriver
– 13mm wrench / Ratchet wrench with 13mm socket
– Dish soap/laundry detergent
– About 1 litre of white vinegar (the cleaning stuff, not the brown stuff you'd put on chips)
– A generic spray bottle and scrubbing brush.
– Around 1kg of bicarbonate of soda
– Lemon juice (optional)
– Other masking fragrances to taste (I used a combo of Chemical Guy's New Car Smell and Leather scent, plus a bit of Febreeze odor eliminator)
You can drive the car without the flooring while this cleaning process is taking place, you just need to reattach the accelerator pedal once the carpets are removed. It does feel a bit weird to drive though as you're missing padding under your foot!
Process:
1/ Crank the front seats right back as far as they will go and remove the floor mats.
2/ Next, pull up the black plastic foot guards on the bottom edge of the doorway. You should just be able to pull these up by hand as they're just clipped on. I found pulling up one side first helped release them. Once up, also pull the fabric door seals just around the base of the door opening and a little up the front side.
3/ Remove the black plastic trim on the inside wall of the footwell outer side. Removing the fabric seals should have exposed the clips for this panel. Get a small flat-head screw driver under the clips to lift them slightly to allow you to remove the panel (these clips should stay attached to the door frame, and don't need to be removed).
4/ On the driver's side, you'll need to remove the accelerator pedal (sounds scarier than it is). It's attached by 2x 13mm bolts that need removing (I kept these in my cupholder compartment for safe keeping) and a small wiring plug disconnecting. The wiring plug can be fiddly to remove. It's held on by a little clip on the top side that can be pushed down with a small flat-head screwdriver, then pulled out at the same time. Took me a few goes and some patience as it's awkward to see and position yourself to get to, but it came out easily once I'd figured it out. Be careful not to snap or force open the bit of plastic that's holding the clip in place. Once removed, the pedal will come away easily. You don't have to remove any other pedals.
5/ Remove the carpet flooring. Firstly pull the tops of the carpets free from the back of the footwells and around the sides. The carpet is literally just tucked under other bits of plastic trim, so just needs freeing. Once out on all sides, pull up the main bit of carpet itself. This is a bit fiddly as the foam is moulded in place to the metal floor, but it's not glued so just takes a little freeing and jimmying. Again, it's just kind of awkward to remove so just be patient.
6/ Once the carpets on both sides are out. Give the bare footwell a little hoover if you can, just to remove any excess musty smelling dust or bits of dirt/food that will have fallen down there, and give it a wipe down with a household spray surface cleaner.
7/ Wash the carpet flooring and floor mats. Not having a garden, I literally did this with the shower head in my bath tub. Rinsing first to get the excess dust and dirt off, then giving both sides a good shampoo and a scrub. Nothing fancy or specialised, I just used some liquid laundry detergent and a bit of dish soap. You'll see the dirt and grime come off them, even if they appear to be clean. Make sure to really push the soap into the foam on the back and scrub the surface (without destroying the foam obvs). I also had a few cracks in the foam on mine, but I was just careful not to open them up too much while washing them (they can be gaffer taped up later when dry). Once both carpets are thoroughly washed, try and push out excess water and set them aside outside with foam facing upward. I'd probably say avoid direct sunlight on them as you don't want them to bake (and for the smell to cure and get worse), but this is all based on conjecture. I don't know if that would happen or not. I luckily had a relatively shaded balcony I could lay them out on.
8/ While still damp, spray the foam and carpets front and back with the white vinegar (I added lemon juice for a little extra acidity). White vinegar is proven to neutralise bad smells and works really well. NOTE: Yes, when you first spray this, it will make the carpets smell strongly like vinegar, but this smell evaporates to nothing as it dries and thankfully takes other smells with it. It's like when you use alcohol in cooking, the alcohol burns off. Give the carpets and foam a good spray on all sides and massage/scrub in the vinegar. Leave them foam facing up again. Then sprinkle a good amount of the bicarbonate of soda all over the foam side. Don't be shy. Work it into all of the grooves and undersides with your fingers (I'll try and post an image I took of this, but the forum's not letting me right now).
9/ Sit and leave to dry. At least overnight, depending on the temperature/weather. The bicarbonate of soda absorbs the smells, and the longer you leave it, the more it absorbs.
10/ Once dry to a decent amount (doesn't have to be bone dry at this stage), hoover up the bicarbonate of soda. Once done, you can do a general smell-check to see how it's done. At this stage, mine was improved, but I could still smell it in the thicker foam areas, so elected to do the vinegar/bicarb cycle again, leaving to dry for another 24hrs.
11/ Again, once dry to a decent amount, flip them over and repeat the same process on the carpet side. You can really scrub the vinegar in on this side to get to work.
12/ Let them dry out thoroughly this time. If some areas aren't drying out, reposition so that they aren't flat on the floor. I found that that sped things up. Once dry, again hoover up the bicarbonate of soda.
13/ Do another smell check. By this point, the foam was at least 75% better and I had to really stick my nose into places to pick up the same smell.
14/ The next step is just letting Mother Nature do it's thing and letting them air out over a couple days. Really try not to skip this step as it does make a difference and it allows the carpets and foam to fully dry out. You don't want to put damp carpets back in your car and then have a different type of bad smell to deal with. I would also sporadically mist light sprays of more white vinegar over the top just for a bit of extra neutralisation. After two days of airing and further drying, I would say that the smell was 90% gone and hard to pick up even at close range.
15/ This stage is optional (I think), but I really didn't want that smell to reappear, so decided to also throw some odor masking/eliminating sprays at it for good measure. To be totally honest, I don't think any of these sprays are 100% permanent, but I figured if they help at least 5%, then it's 5% less musty smell. I mixed up a combination of Chemical Guy's New Car Smell and Leather Scent in the spray bottle (I personally don't think either is spot on: the new car smell is a bit too chemically, and the leather scent a bit too like an old arm chair than new leather, but the mix of the two seems to create a newer leather smell). I also added in a couple sprays of Febreeze odor eliminator (which claims that it does truly eliminate smells on a particle level, so I thought what the hell). The Febreeze is a bit gross/perfumy smelling though, so I only added a very small amount to the mixture so it wasn't traceable by scent. I made sure to really massage the spray smells into the foam, so that it wasn't just treating the surface.
16/ I again let this all dry out again for another 24hrs, and to let the spray smells calm down a little as they can be a bit fierce out of the bottle.
17/ While doing all of this, I was also doing the same process for the floor mats, which had obviously absorbed some of the musty smell over time.
18/ Once fully dry, I gave the carpets and foam a hoover again, just to get any residual bicarbonate of soda or dust off and reinstalled them into the car along with the floor mats.
19/ Once down and back installed in the car with the other bits of trim back in place, I gave them another light misting of the spray smell I'd mixed up, and as an optional extra set off a Meguiar's new car scent odor eliminator bomb in the car. In honesty, I kind of regret this last step, as this bomb didn't have a particularly nice scent. Too vanillary a smell compared to actual new car scent. I was able to leave the windows open a bit and wipe the seat vinyl and interior plastics down with a interior trim finisher to help calm this scent down.
Done.
As I say, the smell appears to have gone after 2 weeks since treating. My philosophy from the start though was even if I reduced it by 50%, then that would still be a big improvement and may only require very light maintenance to upkeep. However, so far I'd say the smell is eradicated 90–100%.
There is very likely other parts of the car with the untreated/cleaned foam (I'm assuming the rear passenger footwell must have some and I know directly under the front seats has, but didn't want to remove them). Obviously if you wanted to do an even more thorough job, you could look at treating these areas too.
I will keep other members posted to see if the smell returns, but so far so good.
I hope that helps anyone else looking to solve it!
TDLR: It's the foam underneath the floor carpets. I’d originally posted that the smell could be cleaned out, but this method only worked temporarily. In the end I just ripped all the backing foam from the driver and passenger footwell carpets out and replaced with sound deadening material and new foam. Months on the smell is much better and hasn’t returned (so ignore the cleaning advice of my first post).
I've had my 2009 S204 C180K for about 5 months now. Loving it so far, but the "crayon-like" old, slightly musty smell of the interior was bugging me. I don't want to drive around in what smells like an old man's car (not that a C Class estate is a young man's car either!). I had kind of got to the point of just accepting and living with it, but it was bugging me every time I got into the car, so knew I had to do something about it.
After doing lots of research to discover the source, I saw a lot of different theories and misinformation – but also no definitive solution either.
So while my wife was away for a week I decided to investigate myself and found the source.
It is not the same smell as a mouldy AC system, it's not the waxy substance around the centre console, or oil burn-off from the engine and it's not the floor mats... it is 100% the foam padding/insulation on the underside of the floor carpets. Other people have discovered this too, but it's buried within so much misinformation and incorrect theories that I thought it worth definitively answering and providing what worked for me to remove it. 2 weeks have gone since I treated and reinstalled the carpets and the smell has yet to return.
I'd identified that the smell was coming from the foam (literally by going around the interior sniffing and pulling things apart). I can understand why people think it's the wax substance or the carpets themselves as the smell obviously penetrates and rubs off onto other things nearby. Once you lift the driver and passenger floor carpets and smell the foam however, there's no mistaking that this is the source. Whether it's the glue that sticks the foam to the back of the carpet and seeps in, or just the foam deteriorating over time – it's the foam itself that holds onto the smell. I assume that this foam is used throughout the car, however (in my car at least), the smell was most prevalent in the driver and front passenger footwells, and treating these alone seems to have eradicated it. I've seen people in Thailand post about completely removing the foam and replacing with cut up yoga mats, but this seemed a bit too extreme for me. I've also seen people re-order the same pieces of carpet, only to find that the new pieces smell exactly the same.
Luckily, getting access to the foam and removing the carpet flooring is a fairly straight-forward job and largely the same process on both sides.
Things you will need:
– Flat head screwdriver
– 13mm wrench / Ratchet wrench with 13mm socket
– Dish soap/laundry detergent
– About 1 litre of white vinegar (the cleaning stuff, not the brown stuff you'd put on chips)
– A generic spray bottle and scrubbing brush.
– Around 1kg of bicarbonate of soda
– Lemon juice (optional)
– Other masking fragrances to taste (I used a combo of Chemical Guy's New Car Smell and Leather scent, plus a bit of Febreeze odor eliminator)
You can drive the car without the flooring while this cleaning process is taking place, you just need to reattach the accelerator pedal once the carpets are removed. It does feel a bit weird to drive though as you're missing padding under your foot!
Process:
1/ Crank the front seats right back as far as they will go and remove the floor mats.
2/ Next, pull up the black plastic foot guards on the bottom edge of the doorway. You should just be able to pull these up by hand as they're just clipped on. I found pulling up one side first helped release them. Once up, also pull the fabric door seals just around the base of the door opening and a little up the front side.
3/ Remove the black plastic trim on the inside wall of the footwell outer side. Removing the fabric seals should have exposed the clips for this panel. Get a small flat-head screw driver under the clips to lift them slightly to allow you to remove the panel (these clips should stay attached to the door frame, and don't need to be removed).
4/ On the driver's side, you'll need to remove the accelerator pedal (sounds scarier than it is). It's attached by 2x 13mm bolts that need removing (I kept these in my cupholder compartment for safe keeping) and a small wiring plug disconnecting. The wiring plug can be fiddly to remove. It's held on by a little clip on the top side that can be pushed down with a small flat-head screwdriver, then pulled out at the same time. Took me a few goes and some patience as it's awkward to see and position yourself to get to, but it came out easily once I'd figured it out. Be careful not to snap or force open the bit of plastic that's holding the clip in place. Once removed, the pedal will come away easily. You don't have to remove any other pedals.
5/ Remove the carpet flooring. Firstly pull the tops of the carpets free from the back of the footwells and around the sides. The carpet is literally just tucked under other bits of plastic trim, so just needs freeing. Once out on all sides, pull up the main bit of carpet itself. This is a bit fiddly as the foam is moulded in place to the metal floor, but it's not glued so just takes a little freeing and jimmying. Again, it's just kind of awkward to remove so just be patient.
6/ Once the carpets on both sides are out. Give the bare footwell a little hoover if you can, just to remove any excess musty smelling dust or bits of dirt/food that will have fallen down there, and give it a wipe down with a household spray surface cleaner.
7/ Wash the carpet flooring and floor mats. Not having a garden, I literally did this with the shower head in my bath tub. Rinsing first to get the excess dust and dirt off, then giving both sides a good shampoo and a scrub. Nothing fancy or specialised, I just used some liquid laundry detergent and a bit of dish soap. You'll see the dirt and grime come off them, even if they appear to be clean. Make sure to really push the soap into the foam on the back and scrub the surface (without destroying the foam obvs). I also had a few cracks in the foam on mine, but I was just careful not to open them up too much while washing them (they can be gaffer taped up later when dry). Once both carpets are thoroughly washed, try and push out excess water and set them aside outside with foam facing upward. I'd probably say avoid direct sunlight on them as you don't want them to bake (and for the smell to cure and get worse), but this is all based on conjecture. I don't know if that would happen or not. I luckily had a relatively shaded balcony I could lay them out on.
8/ While still damp, spray the foam and carpets front and back with the white vinegar (I added lemon juice for a little extra acidity). White vinegar is proven to neutralise bad smells and works really well. NOTE: Yes, when you first spray this, it will make the carpets smell strongly like vinegar, but this smell evaporates to nothing as it dries and thankfully takes other smells with it. It's like when you use alcohol in cooking, the alcohol burns off. Give the carpets and foam a good spray on all sides and massage/scrub in the vinegar. Leave them foam facing up again. Then sprinkle a good amount of the bicarbonate of soda all over the foam side. Don't be shy. Work it into all of the grooves and undersides with your fingers (I'll try and post an image I took of this, but the forum's not letting me right now).
9/ Sit and leave to dry. At least overnight, depending on the temperature/weather. The bicarbonate of soda absorbs the smells, and the longer you leave it, the more it absorbs.
10/ Once dry to a decent amount (doesn't have to be bone dry at this stage), hoover up the bicarbonate of soda. Once done, you can do a general smell-check to see how it's done. At this stage, mine was improved, but I could still smell it in the thicker foam areas, so elected to do the vinegar/bicarb cycle again, leaving to dry for another 24hrs.
11/ Again, once dry to a decent amount, flip them over and repeat the same process on the carpet side. You can really scrub the vinegar in on this side to get to work.
12/ Let them dry out thoroughly this time. If some areas aren't drying out, reposition so that they aren't flat on the floor. I found that that sped things up. Once dry, again hoover up the bicarbonate of soda.
13/ Do another smell check. By this point, the foam was at least 75% better and I had to really stick my nose into places to pick up the same smell.
14/ The next step is just letting Mother Nature do it's thing and letting them air out over a couple days. Really try not to skip this step as it does make a difference and it allows the carpets and foam to fully dry out. You don't want to put damp carpets back in your car and then have a different type of bad smell to deal with. I would also sporadically mist light sprays of more white vinegar over the top just for a bit of extra neutralisation. After two days of airing and further drying, I would say that the smell was 90% gone and hard to pick up even at close range.
15/ This stage is optional (I think), but I really didn't want that smell to reappear, so decided to also throw some odor masking/eliminating sprays at it for good measure. To be totally honest, I don't think any of these sprays are 100% permanent, but I figured if they help at least 5%, then it's 5% less musty smell. I mixed up a combination of Chemical Guy's New Car Smell and Leather Scent in the spray bottle (I personally don't think either is spot on: the new car smell is a bit too chemically, and the leather scent a bit too like an old arm chair than new leather, but the mix of the two seems to create a newer leather smell). I also added in a couple sprays of Febreeze odor eliminator (which claims that it does truly eliminate smells on a particle level, so I thought what the hell). The Febreeze is a bit gross/perfumy smelling though, so I only added a very small amount to the mixture so it wasn't traceable by scent. I made sure to really massage the spray smells into the foam, so that it wasn't just treating the surface.
16/ I again let this all dry out again for another 24hrs, and to let the spray smells calm down a little as they can be a bit fierce out of the bottle.
17/ While doing all of this, I was also doing the same process for the floor mats, which had obviously absorbed some of the musty smell over time.
18/ Once fully dry, I gave the carpets and foam a hoover again, just to get any residual bicarbonate of soda or dust off and reinstalled them into the car along with the floor mats.
19/ Once down and back installed in the car with the other bits of trim back in place, I gave them another light misting of the spray smell I'd mixed up, and as an optional extra set off a Meguiar's new car scent odor eliminator bomb in the car. In honesty, I kind of regret this last step, as this bomb didn't have a particularly nice scent. Too vanillary a smell compared to actual new car scent. I was able to leave the windows open a bit and wipe the seat vinyl and interior plastics down with a interior trim finisher to help calm this scent down.
Done.
As I say, the smell appears to have gone after 2 weeks since treating. My philosophy from the start though was even if I reduced it by 50%, then that would still be a big improvement and may only require very light maintenance to upkeep. However, so far I'd say the smell is eradicated 90–100%.
There is very likely other parts of the car with the untreated/cleaned foam (I'm assuming the rear passenger footwell must have some and I know directly under the front seats has, but didn't want to remove them). Obviously if you wanted to do an even more thorough job, you could look at treating these areas too.
I will keep other members posted to see if the smell returns, but so far so good.
I hope that helps anyone else looking to solve it!
Last edited by Jonoliid; 10-14-2023 at 05:28 PM.
07-05-2022, 01:24 PM
#3
MBWorld Fanatic!
Thanks for the extensive investigation and detailed remedial process.
That makes me wonder:
If the foam is outgassing something with a noticeable odor as it ages, what is the foam made of? And is it nearing the end of its life?
That makes me wonder:
If the foam is outgassing something with a noticeable odor as it ages, what is the foam made of? And is it nearing the end of its life?
07-05-2022, 04:28 PM
#4
Newbie
Thread Starter
I do know that in China there were lawsuits, news stories and recalls for this era of Mercedes having a weird smell, although that was causing people to have headaches, dizziness and low immune system according to reports. It doesn’t seem like it’s been the same thing (in Europe anyway). And that was nearer the time when the cars were new.
07-05-2022, 06:20 PM
#5
MBWorld Fanatic!
I haven’t pulled the floor liner out of a car in decades. The foam backing surprised me. This made me question if it gets worse as the car ages as yours is 4 years older than mine. I noticed it a couple of times and thought it was an oil leak. The E Class had one that smelled just like melted crayons, but this car is tight. The owner of the indie shop that I use thought it might be adhesive in the MBTex seats. He said that using cabin filters with activated charcoal would help. I think it may have, but then the odor of the new Mercedes rubber floor mats overwhelmed any other in the car. All the smells have faded into the background now.
07-06-2022, 04:58 AM
#6
Newbie
Thread Starter
I haven’t pulled the floor liner out of a car in decades. The foam backing surprised me. This made me question if it gets worse as the car ages as yours is 4 years older than mine. I noticed it a couple of times and thought it was an oil leak. The E Class had one that smelled just like melted crayons, but this car is tight. The owner of the indie shop that I use thought it might be adhesive in the MBTex seats. He said that using cabin filters with activated charcoal would help. I think it may have, but then the odor of the new Mercedes rubber floor mats overwhelmed any other in the car. All the smells have faded into the background now.
Some of the foam areas are have polystyrene blocks underneath so the foam isn't as deep as it looks.
Honestly, the job looks and sounds more complicated than it is – it's all pretty easy to do, just going through the step-by-step process, requiring a bit of effort (less than an hour a day over the course of a week) and some drying space.
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Odd Piggy (07-06-2022)
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09-09-2023, 06:40 PM
#8
Newbie
Thread Starter
I just thought of this post again, as in a moment of f*** it I just decided to rip all of the foam out under the front driver and passenger footwells. I plan to replace the foam padding with some sound deadening material and foam sheeting (I figure I might as well get another benefit out of it).
Ive only just done it, so no telling if it’ll work yet but I’ll report back again in a few weeks to see if it did or not.
10-14-2023, 05:22 PM
#9
Newbie
Thread Starter
It reduced the smell for a while, however after a period of warm weather and the car not being used for a few weeks while we were away, it returned. I spoke with a professional car cleaner and ultimately his answer was that you’ll only ever mask the smell unless you get rid of the source.
I just thought of this post again, as in a moment of f*** it I just decided to rip all of the foam out under the front driver and passenger footwells. I plan to replace the foam padding with some sound deadening material and foam sheeting (I figure I might as well get another benefit out of it).
Ive only just done it, so no telling if it’ll work yet but I’ll report back again in a few weeks to see if it did or not.
I just thought of this post again, as in a moment of f*** it I just decided to rip all of the foam out under the front driver and passenger footwells. I plan to replace the foam padding with some sound deadening material and foam sheeting (I figure I might as well get another benefit out of it).
Ive only just done it, so no telling if it’ll work yet but I’ll report back again in a few weeks to see if it did or not.
I did it with both the drivers and passenger sides, replacing it with sound deadening material from Amazon and layers of insulating foam. I kept the polystyrene parts of the carpet backing for the more structural parts, just slotting them back in with the foam removed.
It sounds like a mad job, but honestly when you have all the bits it’s pretty straight forward. The old foam stank, so glad to have got rid of it. Images below are the new foam installed that went under the carpet. As I sound deadened too, I attached it to the car, not the carpet.
It’s been maybe a couple months since I did it and the interior smells much much better. Just much more neutral than it did.
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Sauna (04-18-2024)
