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What's wrong with these plugs?
https://slantsix.org/forum/viewtopic.php?t=46761		 Page 1 of 1
Author:  Reed [ Sun Oct 23, 2011 1:41 pm ]
Post subject:  What's wrong with these plugs?
While swapping the cam in my brother's van yesterday, I pulled the plugs and was unpleasantly surprised to see this:

Image

The van is running a stock Mopar electronic ignition, a Ford e-core coil off of a 1989 351, and the plugs are the NGK ZFR5N.

Why is the ceramic portion so cruddy looking? Why is the electrode and center tip so brown and cruddy looking? I am no expert at interpreting plugs, but I have never seen plugs that look like these.

What is the problem? Weak ignition? Overheating? :?
Author:  Aggressive Ted [ Sun Oct 23, 2011 1:47 pm ]
Post subject: 
They look oil fouled.....a closer shot would help.

I am guessing at week ignition.....
Are you still running a ballast resistor? If so,
What is the voltage at the coil?

If not oil fouled it looks like the voltage is low, around 4 volts or less at the coil.
Author:  SlantSixDan [ Sun Oct 23, 2011 1:56 pm ]
Post subject: 
They're oil fouled (dark and wet-lookin'), not fuel fouled (dark and dry-lookin'), so I don't think weak ignition is to blame here. How much oil does this engine consume?
Author:  Reed [ Sun Oct 23, 2011 2:11 pm ]
Post subject: 
Well, it's hard to say what the oil consumption is. My brother doesn't keep accurate maintenance logs or keep track of how often he adds oil. The tips are actually dry but covered with the brown substance. The white ceramic outboard part looks to be oil fouled, which is understandable given the number of oil leaks my brother's motor has had.

The ignition still has the ballast resistor in place.

This weekend I will get a closer picture and will take some voltage measurements. I am hoping to clean up the engine wiring harness and remove the remainder of the leftover lean wiring.

I can't remember how long ago I installed these plugs. Maybe I will get a spark plug cleaner and try cleaning and reinstalling them. That way I can get a fresh baseline to start tracking things like oil consumption and discoloration.
Author:  Sam Powell [ Sun Oct 23, 2011 2:31 pm ]
Post subject: 
I would say that oil leaked onto the plugs from the valve cover, and it coked onto the plugs from heat.

Sam
Author:  Reed [ Sun Oct 23, 2011 2:32 pm ]
Post subject: 
Quote:
I would say that oil leaked onto the plugs from the valve cover, and it coked onto the plugs from heat.

Sam
Makes sense.
Author:  SlantSixDan [ Sun Oct 23, 2011 2:53 pm ]
Post subject: 
Quote:
Well, it's hard to say what the oil consumption is. My brother doesn't keep accurate maintenance logs or keep track of how often he adds oil.
The best answer to "*shrug* I donno!" is "*shrug* I don't either".
Quote:
The tips are actually dry but covered with the brown substance. The white ceramic outboard part looks to be oil fouled, which is understandable given the number of oil leaks my brother's motor has had.
Point of clarification: "Fouled" refers to the tips of the plugs. The external parts can be dirty, but not fouled. When I say the plug tips look "wet", I mean "shiny" rather than matte/fluffy of carbon/fuel fouling.
Quote:
The ignition still has the ballast resistor in place.
That's as it should be.
Author:  Reed [ Sun Oct 23, 2011 3:03 pm ]
Post subject: 
Quote:
The best answer to "*shrug* I donno!" is "*shrug* I don't either".
You are absolutely right. I don't expect mind reading or miracle answers, just pointers in the direction to look. It is difficult to diagnose the myriad problems in my brother's van since he lives 30 miles away and I only see the van at most every other weekend. I don't mean to be a pest. I do appreciate the large amount of help and guidance I receive from the members of the board.

Anyway, I have ordered new NGKs and will install them this weekend and monitor oil consumption in the motor as best I can. I will also check out the ignition system to the best of my ability and do a compression check.
Author:  SlantSixDan [ Sun Oct 23, 2011 4:18 pm ]
Post subject: 
I wasn't saying you're a pest, I was commenting (perhaps not clearly enough) that your brother seems to expect miracles but, by the sound of things, can't much be bothered to contribute or participate.
Author:  Reed [ Sun Oct 23, 2011 4:28 pm ]
Post subject: 
Well, he's family, so I am helping him with his vehicles while teaching him about things like preventative maintenance and how to maintain old cars. We'll get him sorted in the end. After all, what s family for if not to help each other out?
Author:  exoJjL [ Tue Oct 25, 2011 3:26 pm ]
Post subject: 
Quote:
I would say that oil leaked onto the plugs from the valve cover, and it coked onto the plugs from heat.

Sam
yeah looks like just small amounts coked on for sometime now. As for the electrodes looks like absolutely normal wear to me. There is a little white on them which indicates pre-ignition?
Author:  Reed [ Tue Oct 25, 2011 4:09 pm ]
Post subject: 
All good suggestions. The sad truth is that those plugs have been with this motor through two camshafts and two heads, with the second head causing serious preignition. I am going to replace the plugs this weekend with new NGKs so I will have a baseline to start from in observing plug coloration.

I will also start my own log of oil changes and consumption so I can get a better handle on how the motor is faring.
Author:  exoJjL [ Tue Oct 25, 2011 4:44 pm ]
Post subject: 
You check the gap distance? By the picture they look pretty wide gaped...or is that just how the vans are? Either way you could probably try checking the plug's gap every oil change or 2000-3000 miles. Not sure if gap really can cause pre-ignition.
Author:  Reed [ Tue Oct 25, 2011 4:46 pm ]
Post subject: 
Due to the hot coil, I am running the plugs gapped at .040. Vans get the same gap as cars.

The preignition was caused by a head that was milled too much based on my faulty calculations of the dynamic compression ratio in the motor. I blame the cam shop for not grinding the cam with the profile I requested. Yeah, it's their fault, yeah. :wink:
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