Spark Plug Threads........

[imp]

'04 Expl. 4.0L SOHC 100K miles, bought few months ago, pulled out a spark plug today, it unscrewed very tightly, squeaked some, threads looked to have a brown, powdery material on them. Thought these must be OEM plugs, Motorcraft, in yanking out the rest, found 2 different types of Motorcraft, and 1 Autolite! Obviously shade-tree installed.

They were all platinum, all had gap burned open to 0.070"; decal calls for 0.052-0.056". NAPA guy told me the Motorcrafts had been superceded by a different P/N, OK, so bought 6, checked them against the ones I took out, mechanically they appear similar, as to heat range, same electrode extension, same size hole surrounding center electrode. So there you have what I know about spark plugs, but,.....

Those dry, squeaky threads bother me. Ford Shop Manual says NOTHING about lube or don't lube plug threads in an aluminum head. These things turned so tight, they had to be wrenched all the way out, no turning them with the fingers.

So, do you guys have any spin on lubing plug threads? I will wait before re-installing, 'cause, 2 plug boots absolutely refused to come off, and got destroyed coming off, so tomorrow it's back to town for a set of wires!!

Thanks for any ideas on this! imp

 

[jakedrew]

I have used anti seize on plugs before. They sell little packets at the parts counter.

I havent heard a reason not to use anti seize on plugs, but I could be wrong.

 

[buddychan]

I did the same - put little bit of antiseize on each spark plug.

 

[imp]

Thanks, guys! Reason I asked in the first place, years ago I remember reading somewhere that lubricant on plug threads interferes with proper heat transfer from the plug into the head, and was not trecommended. I thought aluminum might aggravate this situation, if there is one. Over the years, I have usually oiled plug threads, but this was always with cast iron heads. imp

 

[snickstx]

I've also heard the it can throw off the torque reading causing you to overtighten. Not a good idea with aluminum heads.

 

[bookbinder]

hey imp,

Used anti seize on mine and had #7 back out. could have been because I didn't torque to spec. if you have an inch/lb. torque wrench be sure and use it.

rick