Smell of antifreeze in cabin.

[dikidera]

Long story short, last winter my heater core exploded and leaked 3-4 liters of coolant inside the cabin. I replaced it myself with a brand new one, without removing the dashboard, though the fins did get slightly bent and I remember also having to force the coolant pipes a bit to the side to fit it in. I slapped in new o-rings and called it a day. Obviously the smell lingered for a while as the old coolant evaporated from the carpets.

Fast forward a few months and I notice my coolant starting to disappear, but we're talking insignificant amounts, though they do add up over time. And when I start my blower fan, the residual smell of coolant is there. I added around 200ml of coolant. Fast forward to now and every time the car is cold started, and temp reaches 60-70c without any fans on, there is a brief but powerful antifreeze smell in the cabin.

I had a look see at the o-rings on the heater core, but they are fine. If I do have an internal leak again, it's not visible. Either its getting burned off due to a failed head gasket and the increased overpressure is forcing the coolant smell inside the cabin OR it is leaking somewhere behind the dashboard.

Thoughts?

[br0dy519]

First thought would be that coolant is still inside of the extremely dense foam under the carpets. Did you do a full front/rear carpet removal, rinse, compress, and let sit out in the sun for a couple days to dry out? I see no way moisture could ever evaporate out of there, and every time I've had to chase water leaks in my car I've had to leave them out in the summer heat for days to dry.

I would try that plus an ozone generator the remove odors and see where that lands you.

[dikidera]

I admit I have not checked for dampness nor have I removed the carpets to dry, I thought it would evaporate over time, we have very hot summers here and the car was out in the sun for most of the year(its been 10 months since the incident). The smell lingered but then as I explained above, I have coolant loss and can't for the love of me figure out if it's being burned due to a failed headgasket(again) or it's leaking inside the car somehow giving me the antifreeze smell when the car begins to reach op temperature giving me this powerful smell of antifreeze.

[Blacklab467]

Having just removed my carpets and seats I can assure you that if they ever get wet underneath it will never dry. Take them out and plan on having them sit in the sun after rinsing for at least 4 days. Meanwhile you can check the firewall and see if there is any evidence of recent water/coolant ingress on the firewall.

[AylmerQc]

I have the same issue on a 2007 XC70 I bought back in April. The previous owner had the heater core replaced. It's only now with the weather requiring some heat that I'm noticing this smell and the drop in coolant.
I'm hoping it's not a head gasket...how would a small leak at the head gasket be diagnosed?

[dikidera]

Having just removed my carpets and seats I can assure you that if they ever get wet underneath it will never dry. Take them out and plan on having them sit in the sun after rinsing for at least 4 days. Meanwhile you can check the firewall and see if there is any evidence of recent water/coolant ingress on the firewall.

Does the dashboard need to be removed to take out the carpets?

I have the same issue on a 2007 XC70 I bought back in April. The previous owner had the heater core replaced. It's only now with the weather requiring some heat that I'm noticing this smell and the drop in coolant.
I'm hoping it's not a head gasket...how would a small leak at the head gasket be diagnosed?

Exhaust gas test in cooling system. My first symptom for me was my engine radiator exploding, I then did a head resurface + new head gasket. A while later, about 7-8 months after that my heater core exploded while I was idling in the winter.

And now we're back to coolant loss.

[AylmerQc]

Thanks for the information...
If it ever got that bad, I think my wife would tell me to ditch the Volvo, after all the hours and money I've put into it.

I've taken out the carpets on both my 2007 XC70s and it's quite a bit of work taking out the front seats but not the dashboard.
When I found water on only on the passenger side I cut the carpet behind the console straight to the back part that fits on the rear seat. Saved me from having to remove the driver side seat. I have a seam to deal with but with carpet tape it's no big deal.
Taking out the front seats is awkward and cumbersome. You can get away with just loosening the bolts that fasten the seats to the floor and lifting the seat some to lift out the carpet but that's also cumbersome if you're working alone with no one to lift the seat up a bit...

[vtl]

Does the dashboard need to be removed to take out the carpets?

No. Remove the front and side kick panels, pull the plastic trim piece in the door well, cut the carpets behind the front legs of the seats, take it out. You'll never know the carpets are cut behind the seat. I did that even to brand new carpet I bought.

[Blacklab467]

I had my seats out in about 15 minutes for both of them, theres only 4 bolts each and the T-55 to remove the seat belt. You don't have to remove the dashboard or even the console, rear seat bases come out in 5 minutes, no tools required. You will fold the seats with the 2 seatback release levers and remove them out the back door, they're heavy and awkward but will fit out the back door, actually you can remove the passenger seat out the front door if you choose. You don't need to cut the carpets once the seats are out. Seat and carpet removal shouldn't take more than an hour, don't forget to disconnect the battery!

[br0dy519]

For what it's worth after doing the job numerous times I have never disconnected the battery, cut anything, or removed the seatbelt. Just removed seat bolts and pivoted either front or forward to clear and ease the carpet out.