Burnt oil smell occasionally?

[Papasonic]

I am experiencing an odor during a hot restart; the odor to me smells like crankcase blow-by vapor. It does not smell like fuel, coolant or plastic/adhesive type odors as my service tech claims it to be. If the odor was indeed plastic or adhesive related the odor would be constant and not just when restarting a warm engine. The odor also is noticeable somewhat during slow speed stop & go in traffic. It does not produce an odor traveling at constant speed on the highway. I recently had my vehicle in for service and the service tech obviously read the tech bulletin regarding the plastic/adhesive odor emitting from the HVAC system, and decided that was what the odor I described is. His solution was to inject deodorant into the HVAC box to help eliminate the odor. Now the HVAC output air does have an odor of whatever perfume he added to the system. I recently had one of our Chevrolet customer representatives document this condition for further review. I have yet to identify the origin of the odor. My theory is that under certain conditions the crankcase pressure exceeds design limits and vents to the atmosphere instead of being contained within the emission system. I believe that GM knows that this occurs but doesn't yet have a solution and doesn't believe this to be a legitimate problem.

 

[SmoothSonic]

My theory is that under certain conditions the crankcase pressure exceeds design limits and vents to the atmosphere instead of being contained within the emission system.

I am beginning to agree with this theory. I experienced this odor problem when driving up steep hills in stop & go traffic in a city environment which required brief bursts of the accelerator while on an incline in that traffic. After experiencing this symptom, I read this forum and then when I returned to those hills I took it easy on the accelerator pedal while keeping the RPM low. This decreased the majority of the odor and my passenger didn't notice it.

 

[barch88]

Yeah all my cars I smelt this before - I agree with your theory as well nothing seems wrong at all on my car and it does same yhingn


Sent from my iPhone using Tapatalk

 

[SmoothSonic]

I just filled out my Chevrolet customer survey and decided to include a statement about this issue as a design flaw. I wonder if writing about it in the survey makes a difference or if it just gets buried in a database somewhere.

 

[Chevrolet Customer Care]

I just filled out my Chevrolet customer survey and decided to include a statement about this issue as a design flaw. I wonder if writing about it in the survey makes a difference or if it just gets buried in a database somewhere.

Hello SmoothSonic,

I would be happy to formally document your feedback regarding this matter within our system. If you would like me to do this please PM me with your name, contact information, VIN, and current mileage.

Sincerely,

Jonathan A.
Chevrolet Customer Care

 

[AJH]

Wow, just noticed today a smell that was "blow by/crankcase fume" like and wondered if the car in front of me was in bad shape. The smell was there when I got to work, and when I got home that afternoon. I even popped the hood and looked for an oil leak , and checked the dipstick and oil fill cap to see if they was seated properly.

 

[Papasonic]

Wow, just noticed today a smell that was "blow by/crankcase fume" like and wondered if the car in front of me was in bad shape. The smell was there when I got to work, and when I got home that afternoon. I even popped the hood and looked for an oil leak , and checked the dipstick and oil fill cap to see if they was seated properly.

I've done the same drill as you, trying to determine the origin of the blow-by odor. I have thought if I could have someone restart the engine while I was looking under the hood, I may find where the breach in the crankcase vent system was. So far I have not done this, but the odor is coming from somewhere; I am not just imagining the odor, it actually exists, and can be repeated at every hot restart. The service tech at my dealer says that it is not possible for vapors to exit the crankcase vent system, but I beg to differ with his opinion. By design his theory is correct, but there must be certain conditions that this condition exists. Someday a tech that has superior skill and abilities will determine what the actual cause is and can provide a solution. Until then ---

 

[Chevrolet Customer Care]

Wow, just noticed today a smell that was "blow by/crankcase fume" like and wondered if the car in front of me was in bad shape. The smell was there when I got to work, and when I got home that afternoon. I even popped the hood and looked for an oil leak , and checked the dipstick and oil fill cap to see if they was seated properly.

I apologize for the smell you are noticing in your vehicle as well, AJH. If you would like to further discuss your situation with us so we can create a case within our system documenting your concerns, please let us know. Send us a private message that includes your full contact information, VIN, current mileage and dealership name and location. We are more than happy to assist the best we can!

Regards,

Laura M.
Chevrolet Customer Care

 

[AJH]

Well, today I didn't get the odor, but I only drove 5 miles to work and 5 miles back home. I will see if it happens again and will contact if it does.

 

[Chevrolet Customer Care]

Well, today I didn't get the odor, but I only drove 5 miles to work and 5 miles back home. I will see if it happens again and will contact if it does.

Thank you for the update, AJH.

Regards,

Laura M.
Chevrolet Customer Care

 

[Trevinator]

I get a little burnt oil smell outside the car when Im parked after getting to work, but it has been there from day one, so Im pretty sure its normal. it doesn't seem to be using any oil though. I figured its just from the turbo, as I have never smelled this before, but I have never owned a turbo vehicle before either.

 

[AJH]

After a few day smell free, the smell is back. From the vents, defiantly crankcase vapors smell.

 

[Chevrolet Customer Care]

After a few day smell free, the smell is back. From the vents, defiantly crankcase vapors smell.

We're sorry to hear that the smell has returned. Please let us know if you would like for us to reach out to your preferred dealership regarding this concern. We will be glad to help!

Kristen A.
Chevrolet Customer Care

 

[barrstev]

I rented a 1.8L sonic LTZ with the 6speed auto last week, and noticed the same thing. The car had about 26k on the odometer. Since it wasn't a rental I didn't troubleshoot the issue. Interestingly, it would only happen after a shutdown and startup when hot. I would shutoff the engine at long lights (DC has 60-110 second stoplights at every intersection) to save gas, and that's when I noticed it most.

It smelled like an old corvette that I had with a leaking valve cover gasket that would cause oil to burn on the exhaust manifold. What's even more strange is the fact that this was a non-turbo car. I should also mention that the car felt like it had been driven very hard. Chevy's mistake with this car is that it is fun to drive like it's stolen, and I seriously question the lengthy oil change intervals. We'll see how it does long term.

My RS does w/ 3.5k miles does not make this smell, as it most certainly shouldn't..

 

[SmoothSonic]

It's happened to me once again tonight when the outside temperature reached only 43F. If this problem is occurring while the engine is hot, then I wonder how it will perform in the summer heat when it's close to 90F. When it happened tonight, it occurred in the same situation: driving on a steep hill in stop-and-go city traffic. The smell was so intense that my passenger felt sick to her stomach. When I parked, the odor was surrounding the car and I could smell it from across the parking lot. I let the car cool off for 30 minutes. I got back on the road and drove 20 miles home cracking the windows open in hopes the odor would leave, but it remained. I had to take a shower later to get it out of my hair.

So, while driving home I was thinking thoughts about this. Such as: adding a carbon filter to the HEPA filter. Attaching a gauge that tells me when the crankcase pressure reaches too high. Attaching a temperature gauge that tells me when the engine is getting hot (since the car doesn't come with one).

I really think the GM engineers need to come to a solution, recall our cars and get this fixed (or vent it to the exhaust system?). I read a lot of positive reviews about the Sonic last September and none of them mentioned this problem.

 

[SmoothSonic]

Today, when I returned home from work, there wasn't an odor problem inside the car because I wasn't driving on those steep hills from yesterday. It was all relatively flat highways for 20 miles. When I got out of the car after returning home, I noticed the odor again. I then put my nose down onto the hood and could smell this odor seeping out of the cracks around the edge of the hood.

Does anyone know if these toxic fumes are carcinogenic? Or what the long-term effects are on health from breathing this? If carbon monoxide is included with the fumes, then that wouldn't be good if the driver passes out while driving down the road with all the windows closed.

Has anyone checked to see if this smell is possibly caused by a faulty valve cover gasket that's leaking oil down onto the exhaust manifold?
I ask this because I did a google search on this issue in other forums, where people had a leaking valve cover gasket in a non-chevy.

 

[Italianjoe1]

Don't these cars have a charcoal vapor trap in the factory airbox? It's possible that they aren't good enough to stop the smells.

Also, you guys noticing this through the vents, what condition are your cabin air filters in? Is it still noticable with the a/c on recirc mode?

Just curious as on my 1.4 with no cat I don't get any strange smells of any sort from the engine, and as a mechanic i'm more sensitive to them than normal. The A/C does smell funny to me but it's a plasticy, resin type of smell from something in the vent work that may just be because the car is only a couple months old.

 

[AJH]

The smell I get is a crankcase vapor smell, not really a burned oil smell. I don't get it all the time and I haven't figured out that conditions trigger it.

 

[Italianjoe1]

Right, normally crankcase venting is burned back through the running engine, but with the car off and temps still high enough to create some hot air with oil vapors in it, it has nothing pulling it into the engine and could be wafting out of the air intake tract.

 

[Papasonic]

My 1.4 hatch will emit the crankcase blow-by odor at every hot restart. That is the only time I notice the odor. I notice it inside the vehicle, windows up, and the HVAC on outside/fresh air mode. There apparently is an excessive amount of crankcase pressure that vents to atmosphere during cranking and start-up when the engine is at operating temperature. My dealer tech swears that this cannot happen, but obviously he hasn't investigated/diagnosed the issue thoroughly. It definitely is a nauseating odor. I just get frustrated by the staff of so-called service techs that will be quick to explain what the problem couldn't be, but not ambitious enough to investigate or diagnose the root cause of this problem. It shouldn't be that difficult to determine the origin if one is truly a professional technician. I just tire from sitting in the waiting room, waiting for the service adviser to tell me they could not duplicate the complaint; therefore there isn't a problem. Their last diagnosis of the odor was that it came from the sealants used in the HVAC duct system. (Wrong Again)