Ok, after a full year of putting off attempting to change the plugs on my f250, I decided to tackle it this afternoon. I've put 10k km on it in the year I've owned it. It has 171,000km or a little more than 100k miles. As a formerly fleet maintained police vehicle, I had no idea whether the plugs had been touched since it was sold at auction prior to the recommended service interval. Truck runs great, has since I got it. On our recent summer vacation however, I did notice that it was pinging under heavy load carrying my slide-in camper driving through the mountains. Figured that was enough incentive to man up and check those plugs.

Anyway, long story short, I only got one done before my son woke up from his nap. I started with the passenger side front most plug, as I figured it would be the easiest to access if the threads needed repairing.

Overall, plug looked ok. Color seems normal, but the electrode is worn unevenly, tapered side to side, plug gap was 0.067". Plug says motorcraft platinum.

I'm hoping to tackle the rest this week after work now that I have gotten that first one out of the way and the world didn't end.

Unfortunately, I can't post a pic right now, but any thoughts on the plug wear, type and gap? Did these trucks come with platinum plugs from the factory?

 

Motorcraft or Autolite platinum, gapped at .054. (I believe)

I lean towards the Motorcraft only because I had a bad experience with my last set of Autolite APP103's.

 

I got a great deal on ebay for a bunch of Autolite platinums so that is what I'm installing. I gapped the first on to 0.54 . I'm more curious if the motorcraft platinum I pulled out was original.

 

If you can post a pic of the plugs I could tell better if the plugs could possibly be originals. Every plug I pulled on a Ford that takes the AP103/SP479 style plug was single platinum from the factory. No need to double plats IMO and I only run single plats. If it was a fleet vehicle there is a good chance they never changed the plugs and went by the manufacturers suggested 100k mile plug change interval. Depends how they do things. I would say it is possible to have 100k miles on the truck and have the gap only open up to .067" especially if the plug is tapered and rounded well along the ground bar and center electrode. The original plugs should have about 5 complete thread revoloutions on the bottom with a shoulder about 1/2" long above that, should be black oxide coated also.

The Autolite AP103 is fine to use as it is a listed direct replacement. I prefer the Motorcraft SP479 due to the nickel plating however.

 

When I mentioned that the electrode was worn unevenly, I mean the bar that curves over the top, not the center electrode.

Thanks for the description of the motorcraft, certainly sounds like the plug I removed. So, 0.067 isn't a lot of spread for the miles?

 

If the plugs were in 100k miles a gap of .067 isn't that bad considering they started around the .054" mark. Consider though that the rounded areas from spark errosion opened up the actual gap the spark bridged. Either way it is normal to have edge wear and rounding of the center electrode.

I just pulled 6 AP103 out of a 4.0l SOHC V6 in an explorer after 50k miles and the largest measured gap was .060" with edge rounding mainly on the driver side 3 because of the waste spark ignition on that model. The modulars don't use the waste spark system so they are a little easier on plugs.

Here is a pic of an oddly wore double plat autolite plug pulled out of an old 4.0l OHV. You can see the hard chamfer worn on the ground bar. This plug is similar to the old style modular plugs.

 

At 142,000 miles my original plugs were in the .75-.85 range, so yours seem about right to be originals. I think you'll see improved MPG when you get them changed. I saw a 2MPG increase.

 

Sounds good! Looks like tomorrow after work is d-day.

 

Ok, finally got some time to work on the plugs today. I got all of the passenger's side plugs done and the front most drivers side plug finished before I ran into some problems. All of the plugs had excessive gaps and two had some buildup on the top electrode.

After the first plug showed a gap of the 0.067, the rest were 0.072, 0.085, 0.086, 0.082, and 0.073 .

I was on quite a roll and was hoping to finish when I ran into trouble on the drivers side. The 2nd and 3rd plugs had pebbles in the plug holes and I can't get them out. I'm afraid if I remove the plug some or all of them will end up in the cylinder. I need to get some access to a compressor and a blow nozzle.

Anyway, all of the plugs came out fairly easily and so far no stripped plug holes (knock on wood). For the record, Ford's modular motor engineers deserve some kind of prison term for the back two passenger side plugs.

With fresh and properly gapped plus, I'm sure hoping for a bump in mileage when this is all done.

 

Most would agree there are a few chargeable offenses those guys should be brought up on!

Sounds like you're doing things correctly and along with good luck you'll have done a great job in the end. If a compressor isn't handy maybe a small can of compressed air used to clean computer keyboards might work? Its not much but after the COP is removed maybe has enough omph to push those pebbles out? Leave it sit in the sun for a bit---internal pressure will increase giving just a bit more to work with.

Your mileage and performance increases should noticeable too. Thanks for sharing your progress!

 

You might try a long, thin screwdriver to loosen the pebbles then using a shop-vac with a nozzle reducer to suck 'em out. I've seen shop-vac nozzles necked all the way down to soda straw size. They work really well.

 

They were pretty bad, but I didn't think they were as bad as the rear drivers side on the 351W. Guys have been known to make a hole in the firewall on that one.

Definitely. One of the first things I did on this truck was change plugs cause on one of my last trucks I waited quite a while to change plugs and when I did the power and gas mileage went up so far I was wishing I had done it a long long time ago. The gaps on that one weren't too much worse than the ones you took out.

 

I have said many times before that I swear that Ford employs someone to specifically figure out how to make 1 or 2 of the plugs in each engine nearly impossible to get to. On my SD it's #4 & 5, when I had my Mustang it was #8, and with my F150 it was #4.

Someone must get a prize for making it more difficult.

 

Rest assured that there is a special place in HELL reserved for those dudes.

 

Or maybe the Executive Suite? Always a seat to fill there I'm sure!!