Changing plugs on my 2001 Ranger; 4L V6. 310000 miles. OEM originals were Motorcraft AGSF 22FM. I got new Autolite Iridiums XP 5144 from RockAuto. Said they were compatible on their website. Problem is the Autolite Iridiums are 0.2" longer, measuring from the beveled seat to the tip of the ground electrode. Is there any cause for concern that they are too long and might be hit by the piston? Picture is attached. Thanks for any feedback
Stephen B.

 

I'd buy a set of Motorcraft if it were me.

 

Welcome to FTE.

Interesting problem you've uncovered & presented here & good idea to have posted the photo & to question the overall length, as you sure don't want the pistons to contact the plugs.

The Owner Manual 4th printing shows a AGSF-34PP / double platinum plug, as being the original specified for the 2001 OHC 4.0L. The AGSF-22FM's you've removed was for I believe the 4.0L Pushrod engine up to 2000, so wonder if the wrong plugs got installed in your 2001 4.0L OHC, sometime in the past, or maybe the Factory messed up like they did on my 99 Pushrod 4.0L, as I found 3 different type plugs in it when I decided to install the newer design fine wire plug like you have in the Autolite XP 5144, which as you state, is the specified Autolite site look-up plug Number ????

Anyway the Autolite part number on the plugs you received is the correct # according to their site, BUT check the specified Ford spark plug Reach & overall dimension's to make sure the specifications for the Ford & Autolite plugs match. If the published dimensions match, then I'd contact Autolite with your photos & measurements, because it kinda looks like the Autolite factory may have applied the incorrect part number on that plug???? EDIT: OR, the Autolite website has the incorrect part number listed on their part number look-up????

I don't know if you have 0.2" of clearance on your engine or not, that plug is a Lot longer, so I'd be concerned too. More thoughts for consideration, let us know what you find out.

 

^^^^^^^^^^^^^^^^^^^ What he said ^^^^^^^^^^^^^^^^^

 

So if I'm correctly understanding this particular situation it's actually the aftermarket plugs (on the right in the pic) that are the correct length. Huh.

 

We don't know yet. The new Autolite aftermarket plug in the photo has their correct part # on it for his engine, but that # May be on the wrong plug???? He needs to confirm the correct thread Reach for the correct Ford spark plug part number (it kinda looks like the thread Reach is the same for Both plugs in the photo) BUT the overall Length of the aftermarket plug that protrudes into the cylinder is about 0.2" longer than the wrongly specified Motorcraft plug removed / in the photo). SO, at this point at least Two unknowns are staring us in the face, If the AGSF 22FM plug is truly a Factory wrongly installed plug & does it really have 310K miles on it & does it & the Specified Motorcraft AGSF 34PP plug have the same Reach & overall length profile of the removed AGSF 22FM plug in the photo, or does it look like the pictured Autolite XP5144??? If the specified Motorcraft plug, the AGSF34PP (not in the photo) looks like the Autolite XP5144, he's good to go. If it looks like the removed Motorcraft AGSF 22FM, it would seem Autolite may have the wrong part number on their plug, EDIT: OR they have the wrong part number listed in their online look-up, so he Shouldn't install them.

From what I can find, both of the Motorcraft plugs have the same thread reach, just a different Heat range. Right now I'd suspect the Autolite plug may have the wrong part # on it, or the wrong plug listed & I'd not install them.

 

Man, I'm just a simple guy trying to do a simple job! When did everything get so dang complicated? It used to be Prestone green antifreeze, Champion spark plugs, 10w30 oil, and a FL1 filter.

 

I hear you!!! We also assume that the Autolite web site has put up the Correct part number for their spark plug that's supposed to go into his 2001 OHC 4.0L, so that's a Third thing we have to deal with in trying to answer his question, so until we can come by some known good input info, right now the answer is as clear as mud!!! lol

 

Would be great if OP went down to his local auto parts store with one of those XP5144 plugs, laid it down next to an Autolite APP5144 (current, correct DP plug for that engine), compared the plug reach and took/posted a pic in this thread.

 

^+1 & while he's there also lay the current specified Motorcraft DP, or Finewire design plug out for a side by side comparison to the fine wire Autolite XP5144.

From what I've so far been able to find, the removed Motorcraft AGSF 22FM platinum plug in the photo, is just a different heat range than the specified AGSF 34PP that should have been in there. They both seem to have the same specified Reach & amount extending beyond the threads into the combustion chamber, so seem to be the same mechanically, just a different heat range center electrode.

Now the updated design fine wire center electrode Motorcraft replacement plug AGSF-34FP should also be laid out beside the Autolite XP-5144 plug for comparison, since he wants to use the latest design updated fine wire plug. Will be interesting to hear what he finds.