I read your article, good job. So 14 ft-lbs may be the reason we see alot of blown plugs. They just unscrew and pop out or maybe they waller around and the threads wear away till it pops out. It is nice to have real data instead of hearsay.

Perry

 

I just got an 01 EX V-10 w/140K miles. It seems to be running great so I thought I'd just check the torque rather than replace plugs now. To check torque on installed plugs would I merely dial in 14 lbs and see if they tighten any or should I loosen them and then retorque them - or does it matter? Thanks

 

set it to 14lbs and see if the wrench clicks right away or if the plug tightens up..

no need to loosen.

 

My searching has revealed that antiseize lubricant can have an adverse 15 to 30% change in the callout for torque specification tightening. Seems to make sense as it is a lubricant.. further quality sparkled such as Motorcraft have a special coating on them which automatically lubricates and protects them, indicating the manufacture and the Ford manual not to use any antiseize lubricant.

 

Very old thread, but heck, since we're here:

1999 F-53 over 90,000 miles when I did this.

To get them out, I sprayed some liquid wrench down each spark plug hole the day after I parked it for the winter. The following spring when I went to start getting it ready for use, I slowly and carefully started each one turning. None of them were as tight as I put them back in.

The service manual says they should be tightened to between 7 and 14lbft, so when I decided on 12lbft. I verified my torque wrench was reading accurately at such a low value by clamping the square-drive in a vice, marking the handle at 12", and pulling down with 12lb of force according to my fish scale that all of the airlines agree is accurate for my luggage.

I used a very slight amount of anti-seize on the leading half of the threads when I installed them. I don't like the idea of anti-seize myself, and the service manual doesn't mention it, but I'd prefer to be able to remove them in the future without taking threads out with them.

Everything went well. I'll recheck torque on them after 10,000 miles elapses.

 

^^^Not try8ing to be too snarkly but you ignored the common practice or using dabs of nickel-based anti-seize on the Motorcraft plug threads torquing them to no less than 22 ft/lbs? What's your idea or reasoning there?

For those interested here's a thread I found fascinating: Plug Test to Failure

 

I did use just a little anti-seize, but my reasoning for the rest is inspired by page 303-07A-6 of the factory service manual:



It says to "Follow the removal procedure in reverse order". Taken literally, the removal procedure never mentions removing anti-seize from the threads, so I never should have added any to the threads, LOL. There is no mention of anti-seize in this section.

Anyways, I went into it certain that I don't want to install any inserts if I don't have to. I decided on 12lbft because it is 71% up in the specified range of "7-14lbft". I had also decided that the factory service manual specifications must be close to what the factory installed the plugs at a couple of decades and 90,000 miles earlier, so maybe it isn't all bad. I decided to add a smidge of anti-seize (make and model recommended by @JWA in this post) so the plugs wouldn't pull the threads out next time around. I didn't want to use more than that so as to not overly lubricate my torque reading and pull on the threads harder than necessary. I only did the top half of the threads because the anti-seize would get pushed further down as the plug was screwed in.

I decided that if they feel like they are tighter when they come out than the 12lbft I intended to put them in, then I'd re-think 12lbft. They definitely came out with less torque than 12lbft. On the last few plugs, I wanted to measure how much torque it took to remove them, but my beam-type torque wrench didn't have any indications at such a low reading. Instead, I used my trusty digital luggage scale (which is actually a digital fish scale) on 3/8" breaker bar at 12" from the axis and pulled with it. I got readings at right around 10 pounds when they started turning.

I have the maintenance records on this motorhome all the way back to just after the first owner. They start at around 20,000 miles and all of it appears to have been done by professionals. I see nothing done to the spark plugs, heads, etc. except for a single coil replacement like a decade before I bought it. That tells me that these plugs were installed by the factory unless someone had swapped plugs without pay and/or gotten in there and tightened them every once in a while. I also believe that if someone was doing that, they'd likely be a lot tighter than ~10lbft.

Prior to doing this, I had done probably too much research down every rabbit hole I could find. Most of it indicated somewhere between 20 and 55lbft of torque on the plugs. I did see @R&T Babich's recommendation to me of 22-28lbft, and kind of put it in the bucket of "why does everyone want me to put 150%+ torque on these plugs when we're all scared of stripping them out?" I finally decided that stripping threads out is more permanent than under-torqueing plugs, so I'd try living in the factory range and see what happens.

While we're here, I forgot a step after this:

After pulling each one out, I sprayed some carb cleaner down each hole to wash out any residual Liquid Wrench. I let each dry for a few minutes while I installed the previous plug's coil and removed the next plug's coil and fiddled around with whatever else. After all the plugs were back in, I started it and let it idle for a few minutes, then changed the oil.