Reading my spark-plugs

[JHZR2]

depending on where the oil was on the plug... on soome/most/all DOHC engines, there is a cylinder that is friction fit into the head, and has a rubbr seal on the valve cover side. Often these seals or just plain seepage from underneath will allow oil into the cylinder that has the spark plug at the bottom... (sorry for the poor explanation)

This can cause oil to come into the threads, dirty the boot of the spark plug wire, etc.m etc. Id imagine it could find its way all the way to the outer edge of the spark plug if it seeped all the way through the threaded section, or, you could have 'wet' the plug with oil when pulling it out.

Ive seen oil in the spark plug tube many times before, and it makes the plug look oily on the threads... no real harm done though...

JMH

 

[Vspec]

Looks like oil was on the threads, when I pulled it out it looked like it ran down to the tip. I was just concerned.

On a side note I COULD NOT BELIEVE HOW CLEAN THE PISTON WAS!

 

[JHZR2]

yeah... check the seals in the valve cover...

Last one I removed, my mother's plymouth breeze 2.0L, and my GF's 1.8L integra engine were identical... the cylinder was 'jammed' into the casting of the head, and likely some anaerobic sealant was used in there, as it was really tight... but there are rubber rings that go into the valve cover holes, which no matter how good they look could be leaking.

Was there oil on the boot of the spark plug wire that you pulled out? If so, there's your culprit... though not always.

If the piston was so clean, then youre not burning oil, IMO.

JMH

 

[mechtech]

If the plugs re in 'wells', oil on the threads is very common. The valve cove gasket is weeping a little.
The white tips simply show you are burning everything off. Plugs don't color with modern fuel like they used to.
To actually read a plug, you have to look at the base of the insulator, not the hotter tip of an extended tip plug.

 

[Vspec]

Ok, so to let everyone know the vehicle in question is a 03 Nissan Sentra SER Spec-V with a QR25DE engine. It’s been auto-rxed, and only run Redline oil or Mobil oil its whole life. It sees easy driving with a tad of aggressive\spirited driving in between, most trips are medium length. So heres what’s up...

Yesterday I go to York Nissan to pick up some maintenance parts. I get plugs, PCV-Valve, and a new drive belt. I replaced the PCV-Valve easily, and then went on to the plugs, all the plugs were white tipped, looked like someone had stuck them in flour and then dusted them off. What does this mean?

Also on the cylinder closest to the driver’s side either 1 or 4, the plug had OIL on it! Not a ridiculous amount either. I took a flashlight and looked into each cylinder and I could see the top of the pistons, NO CARBON AT ALL was visible from the top of the sparkplug whole. Even on the cylinder with oil on the plug.

I called my brother who is a Nissan tech, he told me not to really worry because a little bit of oil leaking into a cylinder isn't a very big thing, he told me it will just lubricate the upper cylinder walls, and as long as my compression and a leak down test show im good not to worry.

Opinions?

 

[Winston]

Was the oil in the depression in the valve cover where the plug sits? Or was it on the tip of the plug? If it was on the tip of the plug how could it be white.

White plug tips are normal these days due to the really hot spark put out by the new ignition systems.