Weird Smell: Wet Dog, Crayons?

[99TurboBrick]

I purchased my dream SUV, a 2006 XC90 Ocean Race.

It came with quite a stubborn smell. It's hard to describe. To me it's more like wet dog, but a friend described it as "crayons".

Apparently many mid 2000's higher end European cars (VW, BMW, Audi, Mercedes Benz, Volvo) have the "crayon smell" problem.

Exact cause depends on who you ask. Reasons have included:

1. Sound deadening material.
2. Cosmoline (it's been said this one is not possible, because it wears off in a year?)
3. Various foams, glues.

I've had a full interior detail, and treated with chlorine dioxide twice. The smell comes back within a day.
The smell will now spread to whatever item I put in the car....a new sunshade, a new seat cover, etc.

I've detected no moisture anywhere. Sunroof drains fine. I think the AC drains fine, but will double check. No moisture anywhere on the carpets. My detail guy did not mention anything problems like this.

So here I am, trying to decide what to do. If I knew exactly what the cause was, exactly what parts I would need to remove, then perhaps I could make a decision. Could end up being someone else is going to get an otherwise nice Ocean Race with only 85k on the odometer.

[matthew1]

Hi 99TB. A couple thoughts:

Did you check Carfax for any flood report?
A blacklight might help look for mold/stains on surfaces.
Ozone machines are cheap now if nothing else produces a resolution.

[99TurboBrick]

Carfax is clean, no flooding.

Blacklight is a good idea, will try that!

Have not tried ozone, but have done chlorine dioxide twice (about to do a 3rd treatment tonight with a double dose). I've read that chlorine dioxide is actually better, and easier than ozone (but more pricey in the long term if you treat a lot).

[99TurboBrick]

Here's a good article on chlorine dioxide vs ozone. Of course, the website is a company that sells chlorine dioxide, so take that for what you will...

https://biobombs.com/blogs/news/ozone-v ... or-removal

[Capndirk]

When I did some work on my '09 after I first bought it, I found sticky syrup like residue inside the shift console. Apparently the PO had sweet sodas slopping over from the cupholders draining into the center console. It could be an aroma source in your case.

[ggleavitt]

Has someone removed the carpet floors under the front footwells and validated that the smell is not coming from the structural foam floor or below it? Not to be confused with carpets being wet, this is the residual smell and the foam itself will need cleaned and treated.

See photo (from my old 5 cylinder), this is the area you want to expose and it's the part that you'll remove that is the focus (you'll see something on the floor maybe to validate but it's the foam you'll want to check). Driver side piece is more or less the same (less the amplifier). Pull both sides to be sure.

One perhaps dumb question, has the cabin filter been replaced? It'll most likely be the charcoal version (IAQS), the thicker insert.

On another note, see my signature below and let me know if you ever need anything Ocean Race specific. I posted a thread-https://www.swedespeed.com/threads/volv ... rb.633229/ on my refurb back in 2020. I'm still driving mine daily and it's in near perfect condition.

Good luck with your smell.

[99TurboBrick]

I've seen that Ocean Race thread before! Thanks for posting that, I was checking it out around the time I got mine.

Cabin Filter - NOT a stupid question. It was pretty new, but I did remove it as I wanted to treat the vents. I've put them in recirc while the chlorine dioxide was in the vehicle, and I've got some spray I'm going to put in this weekend. I've got a new FCP hepa filter I'll put in at some point after I diagnose what's going on.

Carpets - Have not lifted them yet. What I've read is that the sound deadening asphalt adhesive is the main culprit of the "crayon" smell. However, I read that the foam underlayment that sits above it will absorb that and continue to off gas even after the sound deadening material is removed. Yikes. Anyway, it's worth peeling them up and taking a look for moisture. The blacklight idea mathew1 had was good, and I need to do that also.

[abscate]

When my heater core was leaking I had syrupy smell in the car for weeks. I finally did a major carpet pull and rinse of foam, multiple cycles to get that smell out

[99TurboBrick]

I recall your story about the heater core leak/carpets. Yikes! I'm familiar w that smell as my S70 has also had some coolant leaks, including a drip from a heater core pipe that was not tightly secured. I wish this was a coolant smell, at least I would have an idea where to begin.

I just went over the floor w a blacklight. Nothing stands out. The smell seems to be *everywhere*, I can't pinpoint a single origin.

I can try to start peeling back some areas and see if I find anything, or if I notice the smell is worse in places. In the meantime, guess I'll have to try more mitigation. The chlorine dioxide has worn off after 2 days, so I'm back to status quo. I've heard good things about Ozium gel for absorbing odors so will try that next.

[BlackBart]

Maybe...it's wet dog and crayons....