Spark plug help

[Masterd]

Hey guys,

Just ran outside to do a quick read on a few of the spark plugs I replaced a while back and I found something interesting. I pulled all 3 drivers side plug and the middle one had oil on the threads and a little bit near the top of the plug (not the electrode end). The front drivers side plug had a little in the same areas, but not as bad as the middle, and the back one had even less.

I'm not sure whats going on here. The engine has 284,000 on it right now. It doesnt burn oil at all, but the rear main leaks quite a bit. The electrodes tell me that it might be running a bit lean.

Any help is great!

 

[kit352]

do you have a valve cover leak? electrodes dont look that bad.

 

[Masterd]

No valve cover leak that I can see upon quick inspection.

 

[Tony H]

The burn of the plugs look good. For them to be so clean at the electrode and not the threads I would suspect it would be leaking down from the Valve Covers and into the threads.

 

[JDraper]

Yep..it looks like you have a valve cover (or similar) leak somewhere.


Other than that, the plugs look pretty decent.

 

[Masterd]

Thats good news.

Ill have to take another look for leaks.

 

[4.0Rerolpxe]

hey

i need a little help on sparks as well, on the '93 4.0 OHV, isn't the number 5 spark plug the back one on the passengers side?

 

[Masterd]

COIL
3 4
2 6
1 5

Engine
3 6
2 5
1 4

Plug 5 is middle drivers side, the same on of mine that had the most oil on it

 

[5.0]

How could it be a valve cover leak? All of the plug that is outside of the head still looks clean. Then there is the small part that seals to the head. Then the oil is on the part of plug that's inside of the head.

It seems to me like a valve cover leak would have the rest of the plug (like where the socket goes) covered in oil too.



:navajo:

 

[Tony H]

The oil can seap into the threads a lot easier then Climbing up and onto the Hex shape portion of the plug.

 

[5.0]

Wow, that's crazy. I learn something new everyday

 

[Willard]

Usually the spark plug boot keeps the rest clean. That, and the oil is slowly dripping down, it's not really getting thrown onto the plug.

 

[Masterd]

Like I said also, the area arouns the valve covers is bone dry.

 

[protomind]

is it posible that some oil spilled and dripped down during your last oil change?

 

[Masterd]

Not likely