When accelerating hard and revving engine around 2000-4000 rpm I smell burnt oil smell from my A/C. The smell is similar when I open the oil filler cap or dipstick.

Did hunt for oil leaks and solved them:

  1. At cmp sensor, this one had no O-ring. Replaced.
  2. On valve cover. Wiped clean and tightened bolts slightly. Still dry
  3. Near oil filler cap. Probably didn't tighten well. Wiped and tightened.

But it still has burnt oil smell..

  • What's the year/make/model/mileage of your vehicle? I'd check the pcv for proper operation. You may be having some blow-by which isn't getting cleaned up by the pcv and is blowing out the breather, which could be producing the smell you are talking about. Commented Jan 8, 2015 at 16:32
  • Same car. Mazda 3 1.6 2004. Z6 engine. It's running on a new pcv valve and hose. The previous hose connection to intake manifold was lose when changed. The smell was there before the pcv valve was changed too.
    – Andrew Tan
    Commented Jan 11, 2015 at 1:23
  • As the pcv valve is hidden under the manifold how can I test if its functioning correctly. I read about opening the oil fill cap and putting your hand over it for 2 mins and if it has a vacuum. I attempted that but the oil fill hole was too hot to put my hand over. I did observe some oil splattering out and some air blowing out. When I gently put the oil fill cap there seems to be some slight vacuum though.
    – Andrew Tan
    Commented Jan 11, 2015 at 1:35
  • Will MAP readings be able to tell me anything?
    – Andrew Tan
    Commented Jan 11, 2015 at 2:52
  • 1
    Hi Andrew. If you want someone to get your comment you can put an @ symbol in front of their name and they will get notified that you commented and be able to respond. to return a comment to Paulster2 type @Paulster2 . he will now receive this comment since I formatted his name with the @ symbol. Best of luck and welcome to the site!!!!! Commented Dec 18, 2015 at 22:33

2 Answers 2


Have you noticed any oil leaks under the car?

It could be that your oil level sensor seal is leaking and you will not see it because it is accessed under the car, probably higher up, past the oil pan and you smell the burning oil but can't find it because it burns off too quickly. You'll have to wait till the car cools down in order to check the area for oil leakage as well as part replacement. You should locate the Oil Level Sensor in your vehicle and check this first for leakage. And since it's a 2002; I would do an engine flush to loosen any gummed up crap inside the motor and then add new fresh (manufacture specified) oil.

  • Very close! It's the oil control valve aka VVT valve and also the front main seal. I just noticed it today the housing was seeped with oil. It'll be a pain to change it back though as I have to remove the engine mount and lift the engine with a hoist to access it.
    – Andrew Tan
    Commented Dec 9, 2016 at 16:29

Could you smell it when you open engine hood? Normally when you change oil, some gets spilled on exhaust pipe in engine bay. They get hot when rpm goes up, hence the smell. I suggest using some degreaser to clean exhuase pipe and any parts that gets hot.

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