Oil leak damaged spark plug?

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This is about the 2001 Dakota in my signature. I believe it has leaky valve covers. I can also see some oil collecting around a couple of the spark plug heat shields. I have not yet pulled a boot off to check, but will be fixing the problems this weekend. I just read on another site that if oil collects around a spark plug like that it can cause the plug to not dissipate heat correctly and the plug will be damaged, thus needing to be replaced. Here is the link to what I read:

http://www.autohub360.com/index.php/how-to-diagnose-a-leaking-valve-cover-gasket-1820/

I am wondering if there is any truth to that or can I just remove the plugs, clean them off, re-gap and re-install and still be OK? If it needs it I will replace the plugs and wires along with the valve cover gaskets, but I wanted your opinions here first.

This past Sunday my truck would not start. I had to try it a few times and it finally did start but ran rough until I goosed the throttle and held it at about 1500 RPM for a few seconds. Then it started and ran fine and has been OK since then. I wonder if there really is oil collecting on the plugs that caused that misfire? I had no CEL codes stored from it, the truck just would not start.

I also read online that a leaky valve cover gasket will sometimes cause idle problems because it will mimic a vacuum leak. Some of you here may remember not long ago I had an odd idle problem that I posted about, it acted like a vacuum leak but I replaced the Idle Air Control Valve and Throttle Position Sensor and have had no trouble with the idle since, other than a couple times in the last couple of weeks the truck had a rough idle for a few seconds when I started it after it sat overnight. It always revved and came up to normal cold idle though, until this no-start problem on Sunday.

Thanks for your help here. Sorry for the long post.
 
Originally Posted By: Jimmy9190
I also read online that a leaky valve cover gasket will sometimes cause idle problems because it will mimic a vacuum leak.
Never heard that one before.

I also never heard of an oil leak causing spark plugs to go bad, although I suppose it's possible.
 
I had a valve cover leak on my wife's 2000 Kia Sportage. The well the plugs sit in filled up with oil and shorted out the coil, and the motor missed to the point of it barely ran. On a happier note, I've been using Mobil 1 EP 10w30 in the motor for at least 13 years. When the valve cover was taken off, it looked like he motor was put together last week. Clean as a whistle.,,
 
Originally Posted By: Jimmy9190

I also read online that a leaky valve cover gasket will sometimes cause idle problems because it will mimic a vacuum leak.
This is only true on a vehicle that uses a MAF sensor. A leaky valve cover allows air to enter the engine pass and through the PCV to the intake bypassing the MAF. You have no MAF for the air to bypass so it won't give you that problem.

OTOH if your leak is on the same side of the engine as the PCV valve the PCV system will not work properly. This will allow your oil to turn into a giant acidic sludge monster that will eat your engine.
 
Originally Posted By: yonyon
Originally Posted By: Jimmy9190

I also read online that a leaky valve cover gasket will sometimes cause idle problems because it will mimic a vacuum leak.
This is only true on a vehicle that uses a MAF sensor. A leaky valve cover allows air to enter the engine pass and through the PCV to the intake bypassing the MAF. You have no MAF for the air to bypass so it won't give you that problem.

OTOH if your leak is on the same side of the engine as the PCV valve the PCV system will not work properly. This will allow your oil to turn into a giant acidic sludge monster that will eat your engine.


It is true on any vehicle. Oil can leak from a valve cover gasket, down the spark plug tube and foul out the plug. Usually it fills the tube with oil and eats away at the coil boot, then takes out the coil. But it will leak past the threads and cause buildup on the spark plugs themselves.
 
Originally Posted By: bdcardinal

It is true on any vehicle. Oil can leak from a valve cover gasket, down the spark plug tube and foul out the plug. Usually it fills the tube with oil and eats away at the coil boot, then takes out the coil. But it will leak past the threads and cause buildup on the spark plugs themselves.


Yonyon was referring to vacuum leaks arising from a leaky valve cover gasket, not oil leaks.

BTW it sounds strange that oil will leak past the gasketed sealing surface of a spark plug. It would have to be an improperly installed plug and there will be compression leaks when the engine is running.
 
Thanks for the replies. Bad plugs or not, oil-damaged wires or not I have a good project to do this weekend. Clean up the grease and gunk that has collected on my valve covers, manifold and top edge of the heads, then put in new plugs, new plug wires and replace both valve cover gaskets. I will replace the PCV grommet too, even though it is not leaking. No parts store sells it here, not even Rock Auto lists it so I will see if the local Dodge dealer has it or can order one in for me. A new set of NGK plugs only costs about $13.00 and I will feel better about it if I just change them out. I want to do this job as thoroughly as I can and I sure don't want another misfire/no-start.
 
Originally Posted By: Jimmy9190
Thanks for the replies. Bad plugs or not, oil-damaged wires or not I have a good project to do this weekend. Clean up the grease and gunk that has collected on my valve covers, manifold and top edge of the heads, then put in new plugs, new plug wires and replace both valve cover gaskets. I will replace the PCV grommet too, even though it is not leaking. No parts store sells it here, not even Rock Auto lists it so I will see if the local Dodge dealer has it or can order one in for me. A new set of NGK plugs only costs about $13.00 and I will feel better about it if I just change them out. I want to do this job as thoroughly as I can and I sure don't want another misfire/no-start.



Good call. You are there working on it regardless so you might as well do everything since it's really not any extra work since you've gotta pull everything apart anyways.
Its perfect timing too since the real cold of winter will soon be upon us.
 
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