About to change all plugs and wires on a 1999 4.6 F-150 with Motorcraft replacements. Where exactly does dielectric grease need be placed besides the first .5 inch of the inside of the plug boot?
thank you in advance

 

'Brew to the rescue

https://www.f150online.com/forums/4171114-post27.html

Ask him about that video, lol.

MGD

 

He's asking about plug wire boots.

My post was about COP system boots.

 

Close enough - got yer attention - single-finger beer-fueled searches - what can I say


MGD

 

Yea, thanks . It's been boring as hell around here lately.

 

Here - I'll make it up to you and the OP:

https://www.f150online.com/forums/4260830-post16.html

https://www.f150online.com/forums/v8...tric+plug+wire


MGD

 

Yea, that covers everything lol

 

About the video. I did make one last winter, it only played twice on this site , for two members I believe. I deleted it accidentally from a google host (Picaso) album online. However , I did find outtakes (bits and pieces) in another album on the comp itself, but I can't find the original good one. I'll have to make another.

 

Well Dang... after all the posts and suggestions about d.g. on cop's, that theory makes sense. Why the h**l it isn't re-stated over/over, or a link to here ..... ..

 

A bit of a different slant on grease use is this;
The grease provide somewhat of a moisture barrier at the top of the plug to help prevent the spark from finding a way out to the cylinder head.
One of the most important uses is it provides a slick guide for the boot to find the top of the plug since you have no way to see where it's going when you set the coil in place.
When putting the coil back in, twist the coil a bit so you feel it slide down onto the plug and the upper part of the boot sets down on the head without forcing.
Another use of the grease is to fill the boot groove at the top where it contacts the head. This will provide 'some' measure of moisture seal from the outside getting into the plug well.
The grease only lasts a short time in it's soft form as you applied it, before is gets crusty from the engine heat and seems to almost disappear.
Good luck.

 

That's nearly what my wife said last night

 

Thanks all for your comments. It sounds like a good idea to use the grease at the outside top of the boots grooves, but could something else be subsituted that doesn't get dry and crudy as stated and would gave a greater flexability & longevity for use at the top of the boots?

 

Depends on your overall position.
You could use 'a little' clear silicone as a seal but expect it to hang on pretty good when you next want to remove a coil.
It would be a good seal over the long term and good for the mud boggers, off roaders etc.
If your carefull, after the seal is made, you can even wash down the engine without creating an issue of getting water in the plug wells. Just don't use high pressure.
It's a chance thing you would know the cause of if a seal is not good.
I have cleaned my engine bay after plug service without an issue by sealing the boot tops.
Going a step farther, you could even coat the tops of the coils with a thin layer of silicone as extra protection for those who get down, dirty and wet using their trucks for other uses, especially if the potting compound has cracked open.
If the tops of the boots was designed a little different in shape so as to effect a good water tight seal against the head/plug well, there would have been a lot less issues affecting Ford's reputation in this area.
I just happen to feel if this boot design were used in military field situations, the outcome might not be good. They could have improved the design at some point between the the mid 90's when this design came forth and now.
It's a weak point in overall engine reliability.
I have often thought that some aftermarket vendor could design a cover to go over the coils and incorporate a source of outside cooling to help prevent the coils from developing shorted turns due to the awfull heat they must live in.
The worst conditions a coil gets subjected to is in hot weather just after the motor is shut off and no air is circulating in the engine bay.
On my truck, I use a fan cooled trans cooler with thermostatic surface control set to 185° that runs independent and not on any switches. This cools the engine bay faster and limits the max temp in the bay. During days of 90 + temps, the fan may run about 5 to 8 mins to shutdown after you shut off the motor and runs if you are idleing to keep A/C on.
The fan sensor in inside the bay on the trans cooling line from the trans output, the fan and cooler are out front of the A/C condenser

 

Good post Bluegrass, and a great idea. Yea, dielectric does dry up and turn crudy as kitchenguy pointed out. I've thought about using that 3M clear silicone or that other good stuff made by GE, just never have. I've used it allot tho for other applications and believe it would work + last. Cleaning it off on the other hand might be a PITA . It probably wouldn't be so bad if you had replacement boots on hand.

I may try that , - for now, I'm still using the O-Rings you referred me two a few years back. I managed to find the right size that fits tight between the chamber wall and the boot, that was the most difficult part of all that. Well, that and keeping them in position. At first the O-rings would tend to slip further into the chamber. That was cured by wrapping some of that good E-tape just below to create sort of an o-ring seat.

I don't really mention this that much, it's a little extreme for some, but this does indeed work, it was your idea and a damn good one.

 

We are getting this thread a bit off track - this engine has plug wires, not cops.