Our 2002 Outback wagon, (all wheel drive automatic-78,345 miles and it has had all services at required intervals), has just started emitting a sweet syrupy smell after if warms up, it’s definitely coming from under the car front end. We are not seeing any signs of leaks under the car or wet areas inside near the heater core. No visibly wet area under the hood. Not running hot, it’s not running any differently than before the smell showed up.
I had something similar happen with a minivan a few years back. It was a leaky heater hose from the radiator that only leaks when the heater is on. That sweet syrupy smell though is classic anit-freeze smell.
Keep an eye on the coolant level in the radiator. Sounds like you’ve got a coolant leak somewhere. Keep looking until you find it.
Better get it checked for a head gasket leak. Subaru will cover it up to 8 years or 100,000 miles. I have attached the TSB that explains it.
Check for a coolant leak after the car has come up to normal operating temperature and leave the engine running. You may also need to rev it a little to keep pressure up. Check for a pinhole leak. Be sure to keep checking the coolant level while this is going on and don’t let it go down to a unsafe level. You don’t want to have engine damage due to this problem.
Probably an external head gasket leak and you may have to jump through some hoops with Subaru since they’re notoriously stingy in reimbursement.
They will probably add a bottle of sealer and call it good.
I’m having the same experience with my 2006 Outback.
See my posts and the replies here: http://community.cartalk.com/posts/list/333610.page
And here’s another guy with a similar story:
The replies provide various perspectives/advice, but I have as of yet to resolve this issue with my car. As of now I’m assuming it’s a pinhole leak somewhere, but I haven’t been able to find the source yet. At this point I’m leaning toward the heater core, although the smell outside the car instead of inside through the vents still puzzles me to no end. I just recently started getting a very slow build-up of haze on my windshield when I use the front defroster vents, which is often a sign of a heater core leak. Other than performing pressure tests, the two dealers I’ve taken the car to haven’t been much help in tracing the leak, so I’m assuming the heater core (or whatever the source of the leak is) is going to have to completely fail before Subaru will do anything about it…