I bought a 2004 f150 5.4 used. The spark plugs in the truck are not the normal size spark plug. A Mechanic told me a thread replacement kit was most likely installed. I cannot for the life of me figure out what size the spark plug is as all the sockets seem to big. A 3\8 almost fits but is still to biff Has anyone heard of this? I think it might be metric? 11mm socket was to pick. I think it may be 11mm but did not have a long enough socket. Any ideas??

 

Hi.

It take a 9/16" socket - like this:



BTW - to my knowledge there is no thread replacement procedure for these heads due to the design. Could be wrong but to-date have not seen anyone do this on the '04 to mid-'08 3V heads.

Current -spec replacement Plugs are MC SP515's ... STILL a 2-piece design ( don't let anyone tell you otherwise )

This is how they break in some cases:



And this is the correct tool for extraction if one or more does break:

http://www.lislecorp.com/divisions/p...s/?product=484

If yer mechanic has never done these, look fer one that has actual expereince and a high success rate - this is not the time or place for him to learn on YOUR engine, lol.

List of choices:

Motorcraft SP-515 - takes a 9/16" socket

Autolite HTx, Ford Racing M-12405-3V0, etc takes a 9/16" socket

Champion 7989 takes a 5/8" socket. ( 1-piece plug)

E3 E3-70 takes a 9/16" socket. (and should be avoided at all costs - they are CRAP )

Brisk Silver Racing 3VR17YS takes a 9/16" socket ( 1-piece plug, short lifetime )

MGD

 

MGD,

I do think my mechanic, although experienced, was afraid of these spark plugs. I've worked of these plugs before I know how easy they can break. Thanks for the feedback I'll give the 9/16 socket a try agan.

 

Hi.

I just re-read yer initial post. I know of no plug for this engine where a 3/8" socket would appear to be 'too big'.

It's either a 9/16" or 5/8"(Champ 7989 -from the list above). If those sizes don't fit, I suspect something is preventing the socket from seating on the plug hex, giving the perception of an oversize socket.

This is not uncommon - detrius/grime, foreign objects, etc have been known to be found in the bore. I'd inspect closely to see if this is the case.

good luck
MGD

 

Thanks for the info. My mechanic had me all messed up. Anyways I was able to get those bad boys out! i had the lisle tool but lucky none of them broke.

Thanks!