GCVetteMA

Hi,

My 09/LS3 has an intermittent smell of oil burning (like dripping on exhaust) that comes through the AC when on. There is no oil leak and the oil was not just recently changed. I've owned the car three years and lived with it. I was on the forum and figured I would throw it out there.

Anybody else experience this and find a cause?

Thanks!!
-G

vette10'

I have 2010 base model that does same thing, not all the time just randomly

Mad*Max

Did you do a search here? Numerous discussions on this...

James2000

Same issue here, changed oil pressure switch 6 months ago, because it failed and did the valve cover gaskets 2 months ago, cleaned the engine thoroughly, but still get the smell. Mostly when done with a drive and put the car in park and sit for a minute. I’ve searched on here, but usually get better results when I google it and find links to here. I will continue to search, but if anyone has found a link, please post it here. Thank u

GMJim

This is a well known issue and there are a lot of theories on the cause. I put a catch can on my LS9 and the problem disappeared. I've put catch cans on three Grand Sports and two base cars and oil smell is gone. You be the judge. These LS engines suck hot oil vapor from from the crank case into the intake and it builds up and eventually gets sucked into the engine where when burned the burnt oil will find it's way into the cabin, usually when you stop at a light or a stop sign and the wind is blowing in the right direction.

Bruze

Yes, it is an ongoing thing, with no clear resolution. Luckily, my car is okay (so far.)

Dissecting this ^ . . .

Okay, so the catch cans worked, for some unknown reason.

But assuming one has no exhaust leaks, and assuming one doesn't get that odd, momentary puff of wind while the window is open, how does the smell get into the cabin? ALL of the fumes would come out the exhaust tips. I had old junkers as a kid, many burned oil, but I don't recall ever having the odor come into the interior.

I have no answers, just pondering.

GMJim

Unknown reason?? I just told you what the cause is. The smell gets into the cabin through the HVAC system. I recently took an intake manifold off a 2010 LS3 and poured oil out of the intake. The catch can catches the vapor and condenses it into the can before it gets into the intake where it eventually goes into the combustion chamber and gets burned. The reason you don't smell it all the time is sometimes the outside air blows it away from the car. Other times it blows under the car and gets sucked into the fresh air intake. I'm confident this is the cause. BTW GM knows about this. I empty about 3 to 4 ounces of oil out of my catch can every 1500 to 2000 miles. It doesn't take long to fill the bottom of the intake. Google pictures of oil accumulation in the LS intake.

Kingtal0n

I've read that after an oil change, the air pocket in the filter compresses against the barbell at the back of the motor for a moment causing oil to seep from the rear gasket. Then the driver notices 50-200 miles later when the oil finally made its way out/down from that area.

The fix was to install an aftermarket barbell with a better O-ring and made of metal $30-$50 I think



Oil consumption is a thing, however, in order to 'fill an intake' or 'fire oil at the intake valve' there has to be suction. And the only way you can have suction in the crankcase like that is if the vent tube is clogged. So often times this is merely a mal-maintenance issue, where nobody every cleaned/changed the pcv tubes and now the hole is clogged shut and the intake is able to pull a strong suction on the crankcase/oil system.

You can't suck oil into an engine with engine vacuum if the vent is properly sized on the crankcase, as there will be no significant creation of vacuum which is required to do the sucking.

Bruze

Okay, let's assume we have a C6 in good shape, no leaks, good compression, etc.

Combustion air comes in near the radiator. Exhaust exits at the rear. Otherwise, the engine is a closed system between those two points.

By what method, or at what point, do the burned oil vapors get into the heating/AC system?

GMJim

The burnt oil comes out of the exhaust and gets blown under the car and sucked into the fresh air intake. If a catch can solves the problem the cause is obvious.

CadVette

I wondered what the smell was on my car until I figured out I was smelling the tires not realizing I was spinning them until I got to a stop light.

Bruze

So I'm assuming that a C6 with this problem would NOT pass an emissions test, in states where they're required.

Anybody out there get a "fail" for this specific problem? What was done to correct it so it would pass?

Bruze

This makes the most sense so far. ^

It seems that the catch can is only addressing the symptoms of an underlying problem -- a plugged PCV vent.

Kingtal0n

thank you. I spent years examining pcv systems. they are IMO the second most important, or perhaps most important (if you consider it part of the oil system) aspect of engine longevity.

Catch cans are band-aids. The factory doesn't use them- not because they 'forgot' to install one, and left it up to the owner to install one. But because the engine shouldn't ever need one.


if an engine needs a catch can, then it is a bad engine in need of a rebuild. It means pressure is escaping through the piston ring, entering the crankcase, and blowing oil out of the engine at WOT. Which, by the way, is when the intake manifold PCV valve is shut. Meaning no oil can be 'blown' or 'sucked' into the intake manifold/valves at WOT.

Completely unrelated to the oil sucking feature at cruise/idle, which has little/nothing to do with blow-by, and everything to do with malmaintenance or improperly sized pcv restrictors.

windyC6

To "Catch Can"....or not to "Catch Can".....Oh MY !!!!.......Please help us Mr. Wizard !!!!.....

ExxWhy

I spent an hour reading about this yesterday after I saw this thread. Not very confident in any of the theories.

I have the smell on mine, but it definitely does NOT smell like oil burned through the exhaust. It smells like fresh clean oil that was heated. It's going away slowly as some miles and heat cycles pass. The PO had the oil pan gasket changed the week before I bought this car. (Unbeknownst to me, but that's another story) When I first smelled the smell on the way home from buying it, I put it up on the lift and looked for leaks. No drips, but the pan had some residue. Sprayed it with brake clean and it still looks clean now, so at least they fixed the leak. Doubting I have seen the end of "the smell" however.

Gman in NC

I've never heard of this problem. Also never had it happen and I've had my 05 since new. Maybe it has something to do with driving style. I don't really push my C6 very hard.

Kingtal0n

this is exactly what I remember reading about happening. Air pocket hammers the barbell galley causing some oil to dribble out the back of the rear cover. You get fresh oil dribbling down after an hour or whatever, right onto the exhaust. drip. smokes. Hmm I smell oil? Drip is done now, no more comes out till next time. Wheres it coming from? Can't see any leaks now?

R&L's C6

Mine always did it for about 1000 miles after an oil change (and no, there was no spilt oil) then it went mostly away till the next oil change.

Catch can would have done nothing for that.

lbzraptor

Our X5M BMW has had this smell also a time or two as has my LS7 so I guess its just not just something peculiar to a vette.