Weird Smell: Wet Dog, Crayons?

[99TurboBrick]

This was an interesting read:
https://www.volvocars.com/my/news/susta ... f-a-volvo/

I was hoping for some info that said "these years of cars have this material in these places that will emit this kind of smell"...but alas I've found nothing quite like that.

[matthew1]

If you still can't find it, at this point I'd bring in outside experts: other noses.

Get two or four or so family/friends to sniff the XC90 to try to localize the smell. If it's everywhere I doubt you'll ever get to the bottom of it. It's got to be one area or one component.

I'd even back up a bit during this and ask the Outside Experts if indeed a weird smell does exist. "Do you smell something weird?" I'd start there.

Did the detailers say they smelled it also?

This is the classic "taking a step back" from a problem and I don't think it's ever failed me.

[99TurboBrick]

Good advice matthew1, thank you.

I've had a couple friends smell it, but more could not hurt, and maybe they can even detect a source that I haven't been able to.

One of the friends immediately said "it smells like crayons!". This was before I knew "crayon smell" was even a thing!

The detailer did smell it and said if it remained to bring it back and he would:
1. remove the seats and hit all areas of the carpet and
2. use an ozone machine.

Thing is....I don't want to drop more money without knowing what the root cause is. E.g. if it's sound deadening material, what use will carpet cleaning and ozone do? Not much.

At one point last week I thought I had isolated it to floor mats (which would be the easiest fix ever). So I moved the mats into my garage, and the whole garage smelled like the car within hours. But, the car itself still smelled too.

[99TurboBrick]

This was a good article I thought I'd share for anyone in the future reading this thread...

https://www.volvocarssavannah.com/blog/ ... -volvo.htm

[matthew1]

^ I can't believe there is an actual dealer page regarding this.

Another couple thoughts... maybe it's coming from suspension/wheel well, or just somewhere underneath the body? Roadkill? Tar?

Also, if you can section the front from back (interior) with plastic, like interior house painters use, maybe you can at least cross off half of the suspect volume. I would roll down all four windows after the plastic job, then after a day roll them up to "reset". Then test front vs. back.

[BlackBart]

When we first got our ‘04 XC, it had a funny smell. I took it apart, cleaned under the seats and carpet, tried to vacuum out ducts, shampooed. Whenever it was closed up, it was back. I thought uh oh, a dead mouse in the HVAC.
Over time it just went away. We suspected single mom doctor spilling her latte, racing to get tiny daughter to daycare after she spilled her milk and Cheerios under the back seat.

[abscate]

I had a coolant leak in Karla my s70 awd recently. Replaced heater core.

I left the sunroom cracked in a deluge amd got 2 inches of water in the left driver and rear foot wells. I smelled coolant fir week until I got the carpet up and got it dry. I still have residual coolant dried in the foam, so I need to keep the car dry!

[FastidiousSwede]

I'm wondering if you resolved the smell or had any success finding the source of the problem? I have a 2010 XC90 and have nearly the exact same problem. I haven't thought of it as a crayon smell, but there is a pervasive odd smell that has existed and gotten worse over the ten years we've owned it. It might be a musty smell, but it's not obviously so.

Like you, I can't pinpoint where it's coming from. I smell it in the seats, the floor, and pretty much any surface. I, too, assumed it might be some kind of weird off-gassing, maybe from the plastic or leather. I've read that it could just be an "old Volvo smell," but our other, slightly newer, Volvo smells completely normal.

At one point, we had water pooling on the front passenger floor when it rained, which was traced to the cowl and was repaired years ago. At that time, we had the front passenger section of carpet replaced. Unfortunately, that didn't resolve the smell.

Could it be an odor seeping in from the engine compartment? I ruled out mildew in the A/C system when we had that recharged.

I'm more than willing to track this down, but I'm wondering where to start. Is it likely the flooring? Someone mentioned cleaning the foam under the carpet. How is this done?

Any input is greatly appreciated.

[99TurboBrick]

Hello FS. I have not resolved the issue. However, my best guess at this point is the deteriorating underlayment, which is under the carpet.

I reached up deep into the driver's footwell, where it is exposed, and found that the underlayment had broken down to the point where pieces of it would easily be broken off. The stuff just crumbles in your hands.

This crumbly underlayment stuff is just like I've seen in videos where BMW owners pull this stuff out of their cars to remove the crayon smell. (he starts pulling the stuff out at 4:30)


Contrast this with my 99 S70 T5, which I've had for over 20 years, and does not have this problem. It's probably due to a combination of different materials used in the 2000s, and also the S70 has mostly been garaged. The underlayment is still strong. I had to cut out a piece of it when my heater core leaked. The stuff is still tough and does not smell.

As for cleaning foam, that is doable, but a challenge. If you can cut out a section that you suspect has been contaminated, that may be the best route. I brought a cut section from my S70 into my bathtub and washed it and dried it out thoroughly.

What I'm considering is gradually stripping out the interior. I can start with the passenger seat, carpet, and remove the underlayment. Then, replace the underlayment with better sound proofing materials that don't degrade or offgas. I'm considering hiring a professional for this. The trickiest part in my mind would be replacing enough of the new foam/underlayment so that the new carpet fits properly. I figure a pro can probably do this better than me.

Here's some pics of the underlayment/foam in the driver's footwell, and a small piece that was easily broken off. I feel I could just reach up in there and easily break off large chunks of the this stuff.

[matthew1]

Some thoughts: good work on narrowing it down. You can test by putting some in a small container and testing the smell in isolation. BUT: wear a mask at the very least... better, a respirator. I'm pretty sure Biodegradable does not equal Non Carcinogenic. And take precautions when tearing it out, especially.