Hey guys!
2007 F-150. Just put these plugs in last May '25, probably no more than 6,000 miles on them. Maybe getting water from a head gasket leak? Cylinders 1, 2, 5, & 7 with 1 being the worst. The other plugs are fine.

I notices there is rust on the threads of the damaged plugs, but the threads on undamaged are still shiny




Ideas?

 

Yep something is wrong, checking the headgaskets is a good guess. Any loss of coolant or water in the oil?

 

I checked the oil dipstick and didn’t see anything but oil. I have been slowly losing coolant, but very slow. Maybe an inch or two in the overflow bottle in a two week period.

 

You need to be sure to properly torque the spark plugs when installing. Use a torque wrench set at 25 ft-lbs.
The damage seen in your photos is likely caused by improperly torqued plugs.

 

I will use one when installing the new plugs today. Never used one in the past, just the "that feels about right" technique.

 

PLUGS:
were any other changes made at same time as plug change?

what did the previous set look like when they were pulled (6k miles ago)?

if they looked fine, and if you didn’t install the previous set, then i would put in fresh plugs using proper technique / torque. resume driving and then pull one of troubled cyls in about 3k and inspect. next steps based on results.

COOLANT:
wondering you have two issues, and this coolant could be separate from plugs

had you been watching your coolant prior to last 6k miles?

when did the loss start?

i don’t see engine model noted, but on 4.6 the intake manifolds are notorious for leaking at crossover… which is closed to 1,5, 2, 6. coolant will pool into plug wells and typically cause misfires. but if you didnt torque properly, i guess it’s possible that it would deep down in??

suggest taking a close reading of level when stone cold, then monitoring changes (also at stone cold. you can also pull up 1 and 2 coil boots periodically and check for coolant

EDIT/PS: if you didn’t change out boots/springs last time, definitely do that while changing this time.

 

I agree with the post above about the spark plugs not torqued properly. I have had two instances where the "U" shaped ground strap would burn off due to improper tightening of the plug. Is the engine a 5.4 3 valve?

 

yes, I failed to mention that. 5.4 3V

 

Sorry, but I have no input or help toward your problem, rather a question /comment,

was your engine still able to start and run with those plugs, I never seen any spark plug in that condition.

 

I don't know what kind of cheese those e3 plugs are made out of, but don't go back in with those. Use motorcraft or I have autolites in my truck and they've been in for 6 years or more and are fine.
And make sure to torque them to 25 ft lbs