Elusive burning smell

[Huskymaniac]

About a month ago I got all my fluids drained and re-filled. We did the ATF, both differentials, brake fluid and the fuel filter. Immediately after, I noticed a faint burning smell coming from the vents. It doesn't smell like rubber or oil or coolant. It was a bit more pungent. The mechanic thought it was gear oil but he didn't see any obvious signs of a leak. The smell dissipates when the car is stopped and idling. I also don't smell it much after doing a highway drive. I smell it mostly after doing some "city" or "around town" driving. You can't smell it from outside the car. It really only comes in from the vents when it is bringing in "fresh" air.

It is possible they spilled ATF or gear oil when doing the change but I still smell it and it has been quite a long time. It is possible they "bumped" something or didn't get a good re-seal of an o-ring or gasket. It is also possible that the timing was a coincidence and it had nothing to do with the fluid change.

If I have a leak it is a slow one as I haven't noticed any fluid levels changing or any spots on the ground. In fact, the underside has been bone dry. Several months ago, I did have a PS leak from a loose fitting that was leaving some spots on the ground and we got that fixed. I suppose some dripped fluid could have worked its way to a hot part.

But the weird thing is, I swear that it only smells after a "city" drive and it seems like the smell might be fading slowly. But it is still there and that bothers me.

 

[Camu Mahubah]

I've noticed something like that in my 08 Focus recently after an oil change. I only smell it in town. Mine is kinda like oil burning. I cain't see it anywhere. No leaks. Maybe a few drops fell outta the funnel and hit a spot that gets kinda warm but not super hot. On the highway the wind would blow any fumes away. And if the spot got super hot it would have already been gone.

Dangit. I hate letting other people touch my cars.

 

[Huskymaniac]

Originally Posted By: Camu Mahubah
I've noticed something like that in my 08 Focus recently after an oil change. I only smell it in town. Mine is kinda like oil burning. I cain't see it anywhere. No leaks. Maybe a few drops fell outta the funnel and hit a spot that gets kinda warm but not super hot. On the highway the wind would blow any fumes away. And if the spot got super hot it would have already been gone.

Dangit. I hate letting other people touch my cars.


I could be imagining it but I would swear that I don't notice the smell after a highway drive when I have come to a stop at a light at the end of the off ramp but I do smell it every time I stop when driving around town. I am leaning toward a power steering leak but they haven't been able track it down and it seems odd it would have surfaced after having all my fluids done but NOT including the PS fluid. But I guess it could be coincidence.

 

[oggb]

If they got ATF/gear oil (especially gear oil) on a *heat shield* where it gets hot enough to smell but not hot enough to burn off you'll be smelling it for a LOOOOOONG time.

I got about two teaspoons of gear oil on my turbo's heat shield almost two years ago and I can STILL smell it when I have the heat on bringing in outside air!

 

[Huskymaniac]

Originally Posted By: JRed
If they got ATF/gear oil (especially gear oil) on a *heat shield* where it gets hot enough to smell but not hot enough to burn off you'll be smelling it for a LOOOOOONG time.

I got about two teaspoons of gear oil on my turbo's heat shield almost two years ago and I can STILL smell it when I have the heat on bringing in outside air!


I can buy that but why would I smell it more when driving around town? I thought that was weird.

 

[nitehawk55]

When I change the oil in my Taurus the oil from the filter always soaks the front pipe which I wipe off best I can and the rest burns off . I notice with the Amsoil SSO it takes a few days as opposed to a few hours for the burning smell to dissapear . Must say something for how well the oil holds up to heat .

 

[chubbs1]

That stinks! I know this is kind of stupid but maybe a good charcoal cabin filter would help out in the meantime. At least until the stuff burns off or a leak is found.

 

[Huskymaniac]

Originally Posted By: chubbs1
That stinks! I know this is kind of stupid but maybe a good charcoal cabin filter would help out in the meantime. At least until the stuff burns off or a leak is found.


Yeah, given how slight the odor is, I probably could do that. I was thinking of it anyways as it is an older car (1996 Subaru SVX) and tends toward that old car smell. It really had old car smell when I got it. I did an ozone bomb followed by filtration with a HEPA filter with a carbon pre-filter. I then cleaned off most of the surfaces. Other than the burning smell, the car smells pretty good now. The ozone did wonders.

 

[Huskymaniac]

Originally Posted By: Huskymaniac
Originally Posted By: JRed
If they got ATF/gear oil (especially gear oil) on a *heat shield* where it gets hot enough to smell but not hot enough to burn off you'll be smelling it for a LOOOOOONG time.

I got about two teaspoons of gear oil on my turbo's heat shield almost two years ago and I can STILL smell it when I have the heat on bringing in outside air!


I can buy that but why would I smell it more when driving around town? I thought that was weird.


Anyone else with a possible explanation as to why I would smell burning oil/ATF/gear oil only when driving around town? All theories are welcome!

 

[Craig in Canada]

Originally Posted By: Huskymaniac

I can buy that but why would I smell it more when driving around town? I thought that was weird.


If it's an active leak, the higher wind speed may be blowing the leaking fluid somewhere else. Only at very low wind speed does it leak onto something hot which then smells.

Just an idea.

If you think it's left over from service, why not wash down under the hood? I use a hose-end sprayer (like they use for pesticide) filled with Simple Green and diluting at about 40:1. Spray down the engine bay when cold or slightly warm, use a long bristle paint brush (or similar) to agitate any visibly dirty areas and rinse with LOTS of LOW PRESSURE water to make sure you wash all of the SG away.

If it is gone briefly but returns, then it's an active leak. If it never returns, it was a spill. Cleaning it up beats waiting it out...

 

[Huskymaniac]

Originally Posted By: Craig in Canada
Originally Posted By: Huskymaniac

I can buy that but why would I smell it more when driving around town? I thought that was weird.


If it's an active leak, the higher wind speed may be blowing the leaking fluid somewhere else. Only at very low wind speed does it leak onto something hot which then smells.

Just an idea.

If you think it's left over from service, why not wash down under the hood? I use a hose-end sprayer (like they use for pesticide) filled with Simple Green and diluting at about 40:1. Spray down the engine bay when cold or slightly warm, use a long bristle paint brush (or similar) to agitate any visibly dirty areas and rinse with LOTS of LOW PRESSURE water to make sure you wash all of the SG away.

If it is gone briefly but returns, then it's an active leak. If it never returns, it was a spill. Cleaning it up beats waiting it out...


Thanks for the thought. The problem is that the burning smell goes away if I keep the car stopped and idling. In other words, a drive on the highway produces little or no smell once the car is stopped but a drive around town produces a smell every time the car is stopped which pretty quickly dissipates if the car stays stopped and idling. I would say it goes away in 15 or so minutes.

 

[MolaKule]

As one person suggested, do a complete wash.

Another option is to get some oil dye and put it in the PS first and then check for leaks with a UV light after the wash.

 

[Huskymaniac]

Originally Posted By: MolaKule
As one person suggested, do a complete wash.

Another option is to get some oil dye and put it in the PS first and then check for leaks with a UV light after the wash.


Funny you should mention the PS first. We did that and I will have him check for the dye at the next oil change. I'm leaning toward the PS myself. I would think city driving would cause the leak to occur more if it is the PS. The one thing that still bugs me is the timing of it. It happened right after getting the brake, differential, and transmission fluids changed. I suppose a loose line could have gotten bumped. I am also getting a rattling sound which I think might be my PS rack. Perhaps they are related.

 

[JTK]

Originally Posted By: Huskymaniac


Anyone else with a possible explanation as to why I would smell burning oil/ATF/gear oil only when driving around town? All theories are welcome!


I'm not sure what engine & vehicle we're talking about, but have you considered oil leakage in the spark-plug wells? This is a very common occurrence on engines equipped with deep set, vertically (or nearly vertically) mounted spark plugs. Especially once they get some years/miles on them. That oil just pools there in the wells and you'll smell it under certain conditions. I've never seen it bad enough to cause misfires or whatnot, but replacing the plug tower seals is easy on many of them. They're just O-rings.

Joel

 

[Huskymaniac]

Originally Posted By: JTK
Originally Posted By: Huskymaniac


Anyone else with a possible explanation as to why I would smell burning oil/ATF/gear oil only when driving around town? All theories are welcome!


I'm not sure what engine & vehicle we're talking about, but have you considered oil leakage in the spark-plug wells? This is a very common occurrence on engines equipped with deep set, vertically (or nearly vertically) mounted spark plugs. Especially once they get some years/miles on them. That oil just pools there in the wells and you'll smell it under certain conditions. I've never seen it bad enough to cause misfires or whatnot, but replacing the plug tower seals is easy on many of them. They're just O-rings.

Joel


It is my 1996 Subaru SVX with a 3.3L H6 engine. The burning smell is definitely more like a gear oil or ATF than engine oil but I have not ruled anything out.