I'm just looking to get some ideas of where to search and what the potential sources are for this very annoying problem that we have.

Our 2002 Subaru Outback Wagon was bought used in 2004 as a previous lease vehicle. The car did get one of those stupid 'rust inhibitor' sprays applied, which looks like sticky cream. Since day one, we noticed that shortly after starting to drive (engine temperature), the HVAC will pull in some noxious burning chemical smell whenever the car is stopped. The warmer the engine is, the worse it gets. If you get trapped at a long stop, you can start to get light headed and your nose may start to burn slightly. It's not uncommon for us to reach over and turn off the vent fan when stopped. Rolling down the windows is our reprieve.

Since we bought the car, the only major repair was to have both head gaskets replaced. The car continues to leak a little oil, but the smell in the cabin is NOT burning oil. The transaxle appears to be oily at the front drive axles, and for a time I thought it was a transaxle leak that was flinging fluid onto the exhaust manifold. Now I'm not so sure.

If you park the car and sniff around under the hood it's nearly impossible to find a similar odor. There's more chance of noticing the smell outside the car with the hood down. Weird, I know. I presume that, like most cars, the interior air is drawn in from the cowl below the wipers. When the engine is hot, you can shove your nose in that area and not smell a thing. Crazy. The only thing I have yet to do is climb under the car when it's hot.

After six years with this car, I have yet to find the source. It's bad enough to kill resale value. There's no audible sign of an exhaust system leak, although that's one of the only things I can think of. Might anyone else have any ideas on what can create burnt chemical smells that come through the vents? Could it be rust inhibitor on the exhaust system by mistake? As you may expect, "The dealership could not reproduce the problem." (Just like they couldn't find a huge oil leak a few years ago.)

Thanks for any input!

 

My first thought was exhaust leak. But you sound smart enough to have already investigated that. Good luck with your search I hope somebody can help you find the culprit.

 

i used to own a 95 legacy wagon and so did my roomate's dad. I noticed a gasoline, oil burning smell often and he says his car does it too. Yeah, i can only smell it while driving through the vents. I have to have the outside air vent closed and set it to recirculate. It happens with Subies apparently. My roommate tried changing his fuel filter and that didnt fix the problem. The leaks are usually small leaks for me, not so much that it would do any harm, but noticeable where it would cause concern. My oil pan would always have oil on it even though i wipe and clean it, and i never have to refill oil in between oil changes. I ended up smacking my Subie into a concrete barrier at around 5 mile per hour ( it was packed up snow) and the bumper was still semi good. It got a bit rattled, but the radiator fan switch died. I needed a full tune up and new wheels on the car so I bought the Fit and sold the Legacy. The mechanic that I sold it to fixed everything and is enjoying it. It had 210k miles on it, with leaking head gasket and all the other problems mentioned. Subarus are weird but I love them and would go back to owning one in a heartbeat.

For your problems, I think they are mostly fine, I would just keep an eye on them. You might want to ask the NASIOC forum though. Check the header bolts, thats where my noise and smell was coming from. I didnt figure it out until the headers rattled loose and I couldnt drive past 50 mph. I got it lifted and tightened the header bolts and it was fine. Did you change the head gasket or the header gasket?

 

TurboManGT: The would be a logical conclusion. But wouldn't an exhaust leak by audible at some point? Maybe? Maybe not? :le sigh:

Hobbes87: I know just what you mean by the Subaru 'noise'. Tap tap tap tap tap. That's also been there since day one. The only time it stops is when it's off. haha I've heard so many other Subarus doing it that I'm convinced it's by design. The dealership stated that they changed the head gaskets. I didn't know there were two more hiding in there. By "header", do you mean the valves and / or valve cover, or are you referring to the exhaust system? Our car has far less miles than that. Maybe 40k. Still a baby in Subaru years.

 

by header i mean the exhaust. Check where the engine meets the exhaust. The exhaust header bolts, for most cars need to be tightened after an initial 1000 miles or so back in the days b/c of heating and cooling cycles. I think it was more prominent for Subarus to loosen up because there is less surrounding metal which leads faster heating and cooling to due to the Subaru flat four design. Most engine builders tighten everything down after the first few drives. Jegs sells header bolts that wont back out or lose tension.

Your car is much newer, and they should have solved the problem by now, but Subaru is still offering 4 speed autos.

 

Would you expect to hear exhaust noise even from loose bolts, or is it muffled? I'll give that a look. Are the bolts all accessible from the top?

 

Only way to get at the exhaust manifold bolts on a Subie is from underneath, you will have to run the car up on some ramps and remove the plastic under-tray. I suspect what you will find is the the leak is power STEERING fluid. My wife drives an 04 Forester that had wept steering fluid onto the exhaust pipe since it was about three years old. I didn't discover the source of the mystery fluid until I removed the heat shield from the exhaust pipe to change the secondary o2 sensor. On my wifes car thats the right side manifold (passengers side) The flexible fitting going into the steering rack from the power steering pump had a tiny split in it and was slow-leaking fluid that ran inexorably onto the hot heat shield. Wouldn't stink on a cold engine but got really obnoxious when hot (especially in summer) And like yours I couldn't smell it with the hood open. Mine also didn't leave a puddle, because all the fluid was burning off the manifold. Hope that helps! Cheers, Ross

 

what ^ he said. My car might have had that problem too, just didnt notice it.

 

grtpumpkin: That's a great tip. I'll have to look around on the steering hoses. The engine is so wide that it can be difficult to see under it. My Rhino ramps are in the shed for the winter, so I'll have to wait until after breakup.

If I find that the smell is caused by a leaking and burning fluid of some sort and have it fixed, do you guys think the smell would fade away fairly quickly, or should the engine be steam cleaned? I've heard that those canned cleaners can leave a permanent smell of their own.

Thanks for all the replies!

 

I doubt you'll be able to spot anything from above, the steering rack is almost completely hidden under the motor. Its worth a shot though! I couldn't for the life of me figure out how the car leaked fluid for two years and never ran low! It was like the Japanese version of Christine LOL

 

yeah these tiny leaks are hard to detect but they are the ones that worry you the most.

 

Wow I hope that solves the problem for you!!

Nice tip Grtpumpkin

 

Maybe you could carry a carbon monoxide alarm in your car with you and see if it goes off. If it doesn't that'd reduce the chances of the fumes being an exhaust leak.