Losing oil

Tiny
PORTGAS D ACE
  • MEMBER
  • 2010 NISSAN X-TRAIL
  • 2.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 93,500 MILES
Hello, my car engine oil has decreased, and the fourth spark plug has oil on it. I tested it last year the mechanic told me that my engine has pressure. So, my question is, how I know if I have bad piston ring or damaged cylinder wall? Please I need a scientific answer. Thank you
Tuesday, January 18th, 2022 AT 11:58 AM

7 Replies

Tiny
SQM
  • MECHANIC
  • 6,383 POSTS
Hello,

One of the most common causes for having oil in the spark plug is having leaking spark plug tube seal or valve cover gasket.
If your compression is good, then the issue is not in the cylinder head.
Which leads to the valve cover gasket issue.

https://www.2carpros.com/articles/replace-valve-cover-gasket

I have attached the diagrams for a Frontier X-Trail 2.5L. If it is a different model X-trail let me know.
Any questions or concerns please feel free to ask.

Thank you.
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Tuesday, January 18th, 2022 AT 1:12 PM
Tiny
PORTGAS D ACE
  • MEMBER
  • 28 POSTS
The valve cover gasket is new and the compression is normal.
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Wednesday, January 19th, 2022 AT 12:59 PM
Tiny
SQM
  • MECHANIC
  • 6,383 POSTS
Well, as you know it is possible to have a pinched gasket or a cracked cover to have the leak.
Do you know if the spark plug tube seals were replaced?
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Wednesday, January 19th, 2022 AT 1:02 PM
Tiny
PORTGAS D ACE
  • MEMBER
  • 28 POSTS
Yes, all cylinder head parts are new. Also, the gasket is new.
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Wednesday, January 19th, 2022 AT 1:32 PM
Tiny
SQM
  • MECHANIC
  • 6,383 POSTS
Are you getting any smoke out of the tailpipe?
The oil in the spark plug, is it on the threads or was it on the hose itself?

If you have leaky piston rings you will get blue smoke out of the tailpipe, due to oil burning in the combustion chamber. This will foul the spark plug and it will be black due to oil soaking.
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Wednesday, January 19th, 2022 AT 7:13 PM
Tiny
PORTGAS D ACE
  • MEMBER
  • 28 POSTS
The oil in the spark plug went out of the coil, I mean it obvious when someone sees the engine and there is no noticeable smoke, but it has the smell of burning oil in the tailpipe.
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Friday, January 21st, 2022 AT 12:08 PM
Tiny
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  • MECHANIC
  • 6,383 POSTS
If there was a piston ring leak, you would have blue smoke out of the tailpipe, due to oil burning in the combustion chamber.

https://www.2carpros.com/articles/blue-smoke-from-engines-exhaust

Without looking at the vehicle, everything that you have described points to a leak in the spark plug tube seal or the valve cover gasket. This will have oil on the back of the plug and will be on the ignition coil.
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Friday, January 21st, 2022 AT 12:24 PM

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