[Schiben]

I'm just running down the symptoms I have leading me to believe I have a leaking heater core.
-Strong coolant smell in the cabin
-Fogging windows that won't clear
-No detected coolant leaks or smells outside the car

Is there anything else that would line up with this other than a heater core?

 

[Mimmi]

Leaking coolant bottle.

 

[karajaula]

Check passenger side under the carpet, if you smell coolant it's coming from the heat exchanger almost for sure. If you can check also coolant bypass valve

 

[Schiben]

I don't think it's the coolant bottle. I'm not seeing or smelling any leaks on the outside.

As for the bypass valve... I can't seem to find it mentioned anywhere for the 9-3.

 

[karajaula]

Sorry, I tought I was in 9-5 forum ;oops:

 

[davmac]

You are sane. The symptoms do not sound good and point to a leaking heat exchanger (heater core).
If leaking bad enough coolant level will be low and there may be some coolant drained onto the passenger carpet.
Confirm coolant system leak with coolant system pressure tester - and confirm there is not another source for the leak.
I have not replaced a heater core on this car - but looks relatively easy.

 

[URO Parts Support]

Definitely sounds like the heater core. If you don't have time to replace it soon, some cars have pretty easy access to the heater hoses at the firewall, and DIY guys have been known to use a section of tubing and two hose clamps to temporarily bypass the heater core from inside the engine compartment and prevent further leaking. Unfortunately a bypass also means you won't have any heat, which could be unpleasant in WI this time of year. In the meantime you could put a 12V heater/blower on your dash for the windshield.

 

[Schiben]

Thanks everyone.

I took the leap and ordered a heater core. It showed up yesterday. I had to assume it was the heater core since the smell was STRONG inside the car and nonexistent on the outside. I monitored the engine temp over the last couple days. Yesterday was bad as far as the smell getting unbearable. I had to turn the HVAC off and turn it to recirculate. Even then the windows started fogging up from the steamy coolant. Turning the system on only made things worse. Had to keep the windows open for fresh air (although it wasn't dry air since it was raining). An unpleasant and cold commute for a day won't feel so bad as long as I can manage to get it all back together today.


Getting to the heater core was actually quite a bit easier than I was fearing. Taking off a few trim pieces and the glovebox got me pretty much there. Nearly halfway done with the job now. Hopefully I can come back with a good report this afternoon.

 

[Schiben]

PS: Any other quick maintenance jobs I should do since I have the system apart? I was going to do a system flush but I think the cooling system must have been serviced not too long ago. All the coolant looks good and I've never had any issues.

 

[davmac]

IMO just address the heater core and stuff directly connected. Hopefully your heater core was really more like a kit with new o-rings to seal the core to pipes that connect the the heater core to hoses inside the engine compartment.
Also check the condition of the heater core hoses in the engine compartment. They are part rubber and part plastic with quick connect fittings. Our engine compartments get hot so those parts may be brittle or leaking and need replacement.
It sounds like your cooling system has been maintained - so just refill it and forget about the flushing. Inspect other items like the area around the water pump, radiator, thermostat, coolant tank and hoses. Notorious for leaking: Seals near the water pump (above and toward the firewall), the small curvy coolant hoses from the top of the coolant tank and the coolant tank itself.
It is ironic (I think) that heater core and water pump are exceptionally easy on this car / engine when nearly every other maintenance item is a nightmare.

 

[Schiben]

The core was a small kit with new seals for the inner connections and the metal clamps around them. Plus, oddly, the plastic cover that holds it in. I've been through the res tank hoses already and have some nice silicone ones that still feel good. The hoses leading to the core in the engine compartment also felt pliable enough. Worst part of the whole job was disconnecting the metal tubes from the core itself, under the dash. The corrosion and lack of space to get much force on them made it kind of a pain. All good as of the last 24 hours. Still waiting for the coolant to bleed correctly as I'm still getting the Low Coolant warning with a full res bottle.

 

[davmac]

Congrats on a successful heater core replacement.
Sadly it sounds like the coolant level switch inside the coolant tank has decided to stop working. I don't think the coolant level sensor is sold separately. Hopefully it sorts itself out.