slight antifreeze leak someplace. Engine oil leak. CV boot leak. Start there.

 

I constantly monitor fluid levels, and coolant has been constant and there are no leaks under the car. Just got the oil changed the other day (smell started before), and there are no leaks or anything. Both CV boots intact (one had already been replaced). It's not a very strong smell and definitely a gas/exhaust smell. And I just think it's weird that I really can only smell it in the air inlet/vents. Engine compartment doesn't smell like anything. There doesn't seem to be anything wrong with the car, it was just at the shop for the oil change and everything looks perfect. Basically just wondering if there is a common Subaru thing for it. Or if it's a "they all do that" thing. My car does not have a cabin filter and I just ordered a carbon/particulate one for it to install, so that may help. Thanks for the help!

 

Have the cooling system pressure tested. It may be a tiny leak someplace that only happens when hot. can be a heater core with a itsybitsy leak

 

I can also barely smell it when recirculate is off and the heat or A/C is on,

Sounds as if it's not a very significant smell, especially if it's "like every car".

I'm wondering if the rubber seal across back of the underside of the hood is misplaced or missing. Smells, even normal ones, from the engine compartment could escape to the heater intake area. (#7 in this diagram: http://opposedforces.com/parts/lega...s/legacy/us_b12/type_21/body_equipment_exterior/front_hood_and_front_hood_lock/ )

Does this happen when you're out on the road, or just parked, say, in your own driveway. (Could it be drawing in exhaust fumes, albeit very diluted, from other cars?)

Is this a "new" car for you, or is this a new symptom in a car you've had for a long time?

 

Thanks for the replies. This happens in my driveway, so it's not other cars. It doesn't happen every time, and if it was the heater core, wouldn't I smell it on recirculate too? It goes away completely when I'm moving too. What I mean by "every other car" is that the engine compartment doesn't smell really like anything, but if I press my nose against the air inlet I can smell it. I've smelled in every corner of it, but when I smell the air inlet I can faintly smell it.

I will have had the car for a year this December, and haven't really noticed it until now - I may be being paranoid right now and it has always smelled. When it's cold, I notice a gas smell outside the car right when I start it that goes away quickly - I've been told this is normal as cars run rich at first and as long as it goes away you're good. Doesn't seem to be leaking fuel either, as I don't see anything and my gas mileage has been great. And when I put on the A/C or heat it seems to dilute the smell a bit sometimes to the point where I can't smell it at all, and I never smell it with recirc. on or the windows down. Also, this is with just the fan on and the temp control turned all the way to cold. I have not checked the hood seal.

If I smell the air inlet I can smell it but if I move directly next to it into the engine compartment to the fuel lines or something, I smell nothing. Will the charcoal cabin filter help with the smell?

 

Is there a CEL light?

The gas smell can be a few things. It can be a leaking injector line, a clogged charcoal canister, another posability (replace it anyway) is the PCV Valve.
Cars dont run rich when first started as Fuel Injection solved that issue. I think this is closer to your issue. It is not unusual to have a fuel hose leak going to the fuel injector, as that smell is hard to trace down just by nose. It wont do it all the time. Running rich on is a dying Enegine coolant temp sensor.

Also when was the last time this had a tuneup? before anything else start there.

nipper

 

No CEL. Tuneup (plugs/wires/etc.) about 6000 miles ago when head gaskets were replaced. Car runs great, very smooth, steady, proper idle speed. It only has the fuel smell on startup when cold outside, so I figured that was alright and since it goes away so quickly. I will look into the PCV valve, how easy is it to replace this? I know it has not been replaced, so I should do it anyway - car has 85k. Should I go with OEM part or will something from the parts store do? I haven't done an in-depth look but when I tightened fuel line screws I didn't see any leaks, but will check again. It also does not burn or leak any oil.

 

A shop can easily trace down this fuel issue by using a hydrocarbon sniffer. It may be a little hard to find right now, and may have to wait for it to get a little worse to find.

PCV valve can be from any place. It is on the intake manifold. Easy to replace.

 

I went out this morning to investigate, and when I started the car, I smelled a noticeable gas/exhaust smell on the passenger side of the car under the hood. It decreased in intensity after 30 seconds or so, but there was a faint smell afterward. The other side had no smell. I looked around with a light and couldn't see any leaks/wetness on any fuel rail hoses, and didn't hear any exhaust leaks. The exhaust/intake gaskets were replaced with the head gaskets, so that shouldn't be a problem. I understand the PCV valve is on the passenger side of the engine, so this is where I will start. Any other ideas would be welcomed. Thanks!

 

Check the Evap. Emmisions Lines + Charcoal Canister purge solenoid.

This smell happens on ghetto boosted cars when the C-canister is pressurized by the newly added boost, but can also happen if a line is loose or a fitting on the solenoid is broken.

 

I have heard of the gaskets in the fuel system leaking when cold because the rubber gets harder with age when cold. If it is this, it would be hard to diagnose. This would explain why it goes away quickly.

 

Gaskets in the fuel system (o-rings) are easy to diagnose because when they leak your fuel will be spraying out of the leaky area...

Evap Emission leaks can be a pain to diagnose & may requies use of a smoke machine.

 

Thanks for all the replies. While I'm not ruling it out, I have smelled and inspected the fuel lines/canister and do not smell anything, and I have tightened the fuel rail screws. I had a friend look at it objectively, and he smelled it in the same spot as me, which is right where the PCV valve is (in that area next to the throttle body/air flow meter), which I'm hoping is the problem.

Today I went to the Subaru dealer and got a PCV valve, and when I got home and unscrewed it, it was clearly different. The one from the dealer had a very wide end on it (the end that the hose connects to), while the end on the one on my car was very skinny. Therefore the hose wouldn't fit. So I took it back to the dealer, and they didn't have the part I was looking for. And since I forgot the bag it came in I have to come back to get a credit. So I went to Parts Plus, NAPA, and Advance Auto. Only Advance had a PCV valve at all, and it was the one I had gotten from the dealer. So, since I needed a couple other bits as well, I ordered the right one from subarupartsforyou.com, and hope it solves my problem. Are these usually so hard to find??

The PCV I took out had black deposits on it and smelled like gas. It wasn't wet and just looked kind of normal for it being over 8 years/85k. I know it has never been replaced, so it wasn't in too bad of shape actually, and the valve still moved, but it needed to be replaced. Either way, it will be a good thing to have but I really hope it solves the problem.

Also, should I replace the hose that connects to the valve? What is the part number for it?

 

As it seems to be a fuel smell rather than exhaust, and shows up more after the car has been parked than after it has been running a while, I'm with the others on a fuel leak. Residual pressure causes the fuel to leak out when the car is parked, but when the engine area warms up, leaking fuel evaporates quickly, so there isn't the same accumulation of fumes,

There are several rubber hoses, held on by clamps, that could develop leaks. These are sort of hidden in the intake manifold area.

I believe that some time ago there was a problem with one of these hoses in either the STI or WRX that led to a recall. Also, in the Fall there seems to be a sudden increase in the number of postings about fuel smells after parking for a while, which often turn out to be hose leaks.

The attached diagram is for a Forester, but would be similar. (My 07 also has the rubber hoses, but they are shaped in 90 degree turns to accommodate a different layout.)

 

The fainter smell is there no matter if I had been driving for a long time or just started it. I get a brief stronger smell on cold mornings when i start it but it goes away very quickly (within 5 or 10 seconds, so the engine area is still just as cold) to leave the fainter smell behind until the car is off. The smell lingers for a little bit after i turn the car off then goes away but is constant when the car is on. It is a combination exhaust/gas smell. It is not that strong and smells on the passenger side around the PCV valve. If I go to the engine bay in the morning before starting it there is no smell whatsoever.

 

Just a thought but - old or new Subaru cold mornings when I back out of the drive you catch a wiff of the exhaust cold air - heavy exhaust stays low gets sucked into the vent intakes. My landcruiser does the same thing I've noticed it more at the new house than the old one - perhaps how the driveway sits - no wind in the mornings etc? But yes its very obvious that cold temps and the right situation and the system picks up a good bit of exhaust and pipes it into the cabin. Nothing wrong with the car just the end result in a gas engine in cold temps with exhaust being picked up by the cabin fan.

 

I finally was able to replace the PCV valve, and did so with a Subaru part, and the smell seems to still be there. I can describe it as a combination gas/exhaust/chemical-like smell. I also switched to a different brand of gas, but my brother borrowed my car and filled it up with my original brand (Sunoco), so we'll have to wait and see on that. The smell intensity is very intermittent, and like I've said before, I cannot smell it on fresh air heat or A/C, only with full cold fresh air vent. The smell is really only there when the car is running, and dissipates pretty quickly after it's turned off. That has me thinking that it can't be a fuel leak, since I should be able to smell it any time, correct? My fuel smell on startup in cooler weather seems to be normal, as I've smelled the same on many other, new cars now that I'm paying attention. I know these are fuel injected, but it still needs a richer mixture to start the car, then adjusts accordingly from that. I'm planning to bring it to my mechanic this week to get it looked at, because it's really bugging me. Any ideas to point him in the right direction would be appreciated.

 

I said it before, a leaky injector hose. Have him sniff arounfd the entire engine compartment with a Hydrocarbon Sniffer. If he doesnt have one find another mechanic. He will find it even if you can't smell it at the time.

 

I will definitely mention this as a possibility. I saw someone else online have that issue, even on the passenger side too. I didn't see any leaks but might be somewhere I can't see. Thanks for all the help.

 

Took it to the mechanic today, and he heard an exhaust leak right away when the car was running. I thought my engine sounded different but with the way a Subaru sounds I don't really have a good ear for that kind of thing. Put it up on the lift and the exhaust gasket to the head on the passenger side is leaking. These gaskets must have been replaced with the head gaskets, as he did order a head set and I have other new gaskets, but it seems to be an issue with the way it meets up that the gasket went. He's also unsure about the studs and bolts on it, so he'll change those as well. He mentioned that it's a possibility that the front Y-pipe may have to be replaced because it's not in the greatest shape, and may be hiding some issues. He told me not to worry about replacing that unless he gets it apart and finds a problem with it. If it does need to be replaced, he's recommending an OEM one. I looked and one is about $180 on 1stsubaruparts.com.

Either way, thanks for all the help everyone in trying to get this resolved myself. Maybe if I wasn't sick with a stuffy nose I would be able to smell it better! And any tips for this repair or future would be appreciated.

 

Any luck with replacing the exhaust gaskets?

Based on your descriptions in this thread, I think I have a very similar issue with my car. 2003 OB LTD 2.5 with 175,000 miles.

I know the car has a small AC refrigerant leak as the AC system will get low pressure after several months, but that doesn't explain the fuel/exhaust smell coming in. I only get the smell when idling, not when the car is running on the highway.

I had the same thoughts as others:
- install/replace cabin air filter
- check cowl seal - cabin air intake areas for obstructions
- check PCV valve/hoses
- check fuel system gaskets and o-rings
- check exhaust system gaskets

Just haven't gotten to any of these since we just started noticing the smell.


In many states, winter gasoline formulations tend to add a lot more ethanol and/or MTBE than in summer time to change the vaporization and pressure characteristics within the fuel system. This helps increase effective octane rating at lower temperatures and reduce smog at the expense of fuel economy. Fuel formulation is yet another variable to consider and perhaps another reason why folks report these issues during the Fall. Hopefully Ethanol or MTBE is not eating away at o-rings

 

My mechanic replaced my exhaust gaskets along with new studs and nuts, and that cured my problem as I expected it to. He told me that it had somehow worked its way loose so he put everything back up with new parts and loctite, so all is well. Cost me about $100 total. And if your gaskets are fine, winter fuel can definitely give a weird smell. Have you tried tightening your fuel rail screws? Link below gives more info. Good luck!

Subaru Fuel Line Cold Temperature Leak

 

Just noticed that my cv-boot is busted and spraying grease all over the exhaust/cat so thats the likely cause of the smell in my case.

 

CV grease definitely has a strong smell but it's a burning rubber smell more than anything, not like exhaust. My CV boot leaked and that smell stayed with the car for a while before all the grease burned off. When I was helping a friend look at a used Subaru, I smelled that grease immediately when they opened the hood after the car was warmed up. You will recognize the smell after it happens to you, and sure enough, the CV boot on the car was ripped wide open.