Coolant Smell inside cabin.

ericmci · Post by **ericmci** » 29 Oct 2024, 11:50

So it's that time of year when we start turning on the heat in the Northeast.
However, I am smelling coolant coming through the vents and seeing a bit of build up on the windows.
But it goes away after running for a bit.
I have only smelled this recently since using the heat and I replaced the heater core two years ago with OEM Behr. No signs of leaking under the carpet or anywhere.
Heater core hoses are silicone and 2 years old as is the plastic coupling behind the peddle.
I tried to do it right.

Am I looking at a bad o ring or seal somewhere that eventually expands and seals when it gets hot enough?

Coolant level has dipped a bit too a couple of times but I assume that is from drawing more into the core for cabin heat.
Oil is perfect - even had an analysis done this summer and I have crankcase suction with the rubber glove test.

Any thoughts or theories are appreciated.

Thanks!

-Eric

dikidera · Post by **dikidera** » 29 Oct 2024, 12:03

Just one, but it depends if it has any similarity to the later S60/V70 P2 models. If they do not, you can ignore my comment.

When you lift the power steering reservoir, you should be able to see the ECM fan and above it the coolant expansion tank. The ECM fan on the S60s has a permeable insulation that connects the ECM fan to a hose or pipe that goes inside the cabin to draw cooler air to cool the ECM/TCM. I have noticed on my car that the expansion tank is leaking onto this insulation, letting the antifreeze smell inside the cabin.

ericmci · Post by **ericmci** » 29 Oct 2024, 12:14

That is a good possible!
But I have a 99 S70 GLT - P80
Also this summer I replaced the tank and its hoses with silicone.

dikidera · Post by **dikidera** » 29 Oct 2024, 12:21

Yes I understand you have a different car and I did mention that if there are no similarities you can ignore my suggestion. But if there are, it's worth checking out, sometimes hoses aren't on tight, sometimes plastics crack. Additionally if this permeable insulation is there, press on it hard and see if it it's wet or oily.

Post by **scot850** » 29 Oct 2024, 19:39

I would check the underside of the carpet and look for trails from either the o-ring seals at the heater core, or at the bulkhead connector.
I'm assuming you are losing coolant?

Neil.

Post by **abscate** » 30 Oct 2024, 02:17

The heater core runs full flow all the time, heat is regulated in P80 cars by mixing air in the HVAC box, not my controlling coolant flow.

Ergo, if coolant level changes, you have leaks, The smell and misting are tell tales that it is in the core, either orings or the core itself.

It isnt a bad job to drop it. You can pull the hoses at the firewall front, then flush the core with a hose to turn the coolant into water so you dont dump coolant into the interior on this job, or catch the liter in a new garbage bag without holes.

ericmci · Post by **ericmci** » 30 Oct 2024, 09:32

It's not a bad job. Like I said I replaced the core just two years ago. I suppose it could go bad but I am leaning towards the o rings as the smell goes away after running for a bit. The carpet is bone dry on both sides so perhaps just enough is leaking out into the box and burning off while the o rings expand and seal? I have lost coolant but just about the difference between min and max. I'm the guy who replaced the oil cooler hoses with specialty cut silicone hoses from D088. No leaks there since I said good by to the Uro garbage replacement every year.

ericmci · Post by **ericmci** » 30 Oct 2024, 09:34

I am definitely not dismissing your suggestion, just saying I have checked those hoses as I recently replaced them with silicone
because I did have a leak there from a cracked expansion tank.

ericmci · Post by **ericmci** » 30 Oct 2024, 10:02

I am definitely only losing coolant though after running the heater at temp. I replaced the expansion tank this summer and the level was perfect for months only dipped last week after turning on the first few cold days. If the box is full all the time wouldn't it leak regardless of use if the core or seals were bad. What does using the heater do to cause it to happen only in use.

Post by **scot850** » 30 Oct 2024, 10:19

Nothing really. Maybe you only notice it when the heater is blowing as it is warmer air that lifts the smell into the car. It could be the core is bad as Abscate suggests. If it is, it could be leaking into the heating system and draining under the car.

Un-relates to the cabin leak, have you checked you are not getting a weep from the water pump while it heats and cools?

Neil.