Why is there burnt oil on metal inside engine under the filler cap?

Tiny
TMR214
  • MEMBER
  • 2016 HYUNDAI ACCENT
  • 2.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 84,000 MILES
I went to check my oil level today and noticed I was about half a quart low. I saw what appeared to be burnt oil on a metal component under the fill cap that was partially blocking the filler hole. I change my oil every 3,000 miles. Why am I seeing this? What exactly is it, and is it a sign of a problem?

I attached a picture because I can’t explain well what I’m looking at. You’ll see the sludge/residue/burned oil.
Sunday, August 7th, 2022 AT 1:23 PM

1 Reply

Tiny
BORIS K
  • MECHANIC
  • 795 POSTS
Hello,

The burnt residue you see is quite normal.
The metal plate, where the residue is baked on, is part of the crank case ventilation system.
Oil will splash on to the top of the plate and some of it will remain there and get baked on from the engine heat.
The plate prevents oil from being sucked into the crankcase ventilation system

See image below, the valve cover is inverted showing the metal plate and oil filler cap

Hope this helps.

Cheers, Boris
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Monday, August 8th, 2022 AT 4:12 AM

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