[ZkTi]

Hello,
I need some help reading the spark plugs to know the general condition of the engine.
2006 Nissan Teana J31 2.0, QR20DE engine with 350,000km / 220,000 miles.
Spark plugs are NGK PLFR5A-11 after 20,000 km / 13,000 miles.

Below are photos of each spark plug from 2 different directions.
First 3 look nearly identical - clean, white insulator and little deposits on the ground electrode.
Plug #4 has brownish insulator, with one side darker than the other.
Are the clean insulators normal or suggesting lean condition? What could be the reasons for the uneven brownish color on the 4th plug?
Are the white deposits on the ground electrode normal?

Any insights would be highly appreciated.
Thanks in advance.

 

[amc49]

4th plug may be showing injector leaking or oil burning slightly..

 

[ZkTi]

4th plug may be showing injector leaking.

Thank you. Are the first 3 normal?

 

[amc49]

Read my post again, edited. Can't tell with others, you have to look at the porcelain down deeper inside the steel shell where the porcelain meets the metal of shell. Plugs always color up there first before they color out at the end of the porcelain.

 

[ZkTi]

I will try to clean the fourth injector or replace it in case there is no improvement. Hoping it solves the issue so I don't have to deal with an oil leak into the cylinder. Thank you amc49.

 

[1.8TTony]

I will try to clean the fourth injector or replace it in case there is no improvement. Hoping it solves the issue so I don't have to deal with an oil leak into the cylinder. Thank you amc49.

Before replacing OR cleaning the injector......swap it with one of the other injectors. Install a new spark plug and see if the problem moves with the injector.

If the problem moves with the injector, clean or replace it.

If the problem remains with the #4 spark plug location, you've got an oil control problem......to be more specific, you'll need to replace both intake valve seals for the #4 cylinder.

These valve seals are located below the intake valve springs. Replacing the seals is not a very complicated process, but you're gonna need some specific tools to accomplish this task.

Bonus: If you've got shimmed bucket lifters, this is an excellent time to check clearance and install valve lash shims as necessary.(

 

[ZkTi]

Swapping the injector with one of the other injectors is a great idea to isolate the problem. I will also change the valve seals on this old engine, just in case, after I find the tool to release the valve spring. The clearance of the bucket lifters was verified about 3 months ago. All were in spec.
Thank you 1.8TTony.

 

[ZkTi]

Before replacing OR cleaning the injector......swap it with one of the other injectors. Install a new spark plug and see if the problem moves with the injector.

After the swap how many km/miles should I drive before checking it again?

 

[1.8TTony]

After the swap how many km/miles should I drive before checking it again?

I don't know how many miles......the thing happening with your #4 spark plug is referred to as "oil coking".....I imagine minimal signs of oil coking can develop within the first 1,000 miles.

Oil coking is a build-up of carbon which is a result of oil being burned. Oil "coke" is the equivalent of charcoal ashes left behind after you bbq ......only difference is oil coke is hard, it's not a powder.

 

[ZkTi]

I swapped injectors #3 and #4 a couple of days ago. Will check the spark plugs again after 1-1.5K miles.