The whole sparkplug/thread design is stupid on these engines.

There is an aluminum head, with a steel plug. This combo can work, and has for many years, but not so well with Ford's design.

The problem arises with the fact that Ford put a tapered plug in this head. A tapered plug will work loose at times even in a cast iron head. I find loose ones on Fords with cast iron heads all the time.

The aluminum expands faster than the steel plug, causing the taper seat to lose tension, then the cylinder pulsating pressure will cause the plug to vibrate and loosen slightly.

Over time the plug will loosen more, and with only 4 threads it doesn't take much for the pulsations to strip the threads, sending the plug flying.

If Ford had used a washer seat plug similar to GM, and had 8-10 threads from the start, then the plug spitting problem would never have reared its ugly head.

 

Yardbird , EXACTLY!!!!

 

Then please do explain to me why the spark plug gap is closed on the plugs when they blow out. If what you are saying is true, the gap should still be open and just the threads stripped out.

 

I am saying that the plug is far more likely to blow when the vehicle is under load and at WOT.

You can speculate all you want about more threads, less threads, whatever. The fact of the matter is that the possibilty that they will pop is there and there are ways to limit that possibility.

 

So you are saying that the cylinder pressures shoot up, forcing the plug out, and at the same time that same pressure closes the gap on the plugs. How can pressurised air create more force onto the tip than the plug shaft itself?

I am not saying that the closed loop theory you have is not correct as far as contributing to plug ejection. If the engines are too lean, then heat would surely be created. However, many plugs have ejected while driving normal, and in vehicles that have probably never been held at WOT, or ever had a plug change since factory installation.

There have also been quite a few cars that eject plugs also, but the trucks are by far the worst.

As for why the gap is shut on some of the plugs, my theory is that as the loose plug is jumping up and down from being subjected to pressure and vacuum in the cylinder, the plug seat also wears down, causing the piston to slightly contact the plug. This would cause an immediate ejection.

There have been several post I have read that stated there were tracks on the piston from the plug hitting it.

The plug ejection problem was cut dramatically in Nov. or Dec. 2003 when Ford switched to an 8 thread head. This head has been used on all 2 valve modular engines since that time. My '03 4.6 was made in Oct. '03 and only has 4 threads per hole. This is why I check the plug torque on my engine, and why you will read of some '03's spitting plugs.

I still believe the problem would not have happened at all with washer seat plugs and full threads in the head. I have seen too many Fords with loose plugs in cast iron heads.

 

Here is a hint. The electrode gap is caused by a LEAN condition. Not from piston to plug contact. More on this in the morning.

 

I made a typo in the above thread. The change over date to the 8 thread head was November of 2002.

 

I just had the #3 plug blow last weekend on factory installed plugs and only 45000 miles idling down a hill. After doing some research I couldn't believe all the issues with plugs blowing out. Took it to the dealer and they quoted $3500 for a new head. Fortunately I did my home work and found that Ford came out with a TSB in July to try to fix their poor engineering. TSB 7-15-2 for out of warranty repair using lock n stitch repair kit. Price came down to $750. I’ve been a Ford guy for a long time but I think its time to change.

 

find a local shop who's familiar with HELICOILS to put one in for you...I have a guy local to me who'll do one for like $120 or something, only takes about 20 minutes to repair.

 

Try looking up Time-sert thread repair, much better than Helicoils

 

This has been discussed in detail in the 4.6/5.4 and V10 engine forums for the past few years...

Ford has updated both the installation/torque-down procedure at the factory, an "alignment feature", and long-thread heads.

Timeline (REP = Romeo Engine Plant, WEP = Windsor Engine Plant)

December 1996 - 4.6L 4V head alignment feature added
February 1997 - 4.6L 2V head alignment feature added
September 2000 - WEP 2V head alignment feature modified (4.6/5.4/6.8)
November 2002 - WEP introduced long threads on 2V (4.6./5.4/6.8)
May 2003 - REP introduced long threads on 4V (4.6/5.4)
November 2003 - REP introduced long threads on 2V and modified alignment feature.

Torque down procedure, original process:

Step 1 - Zerop torque spark plug (air tool)
Step 2 - Torque to 16-20Nm final torque, monitor at 6-12Nm, and final torque must be reached withint 0-360 degrees.

New process:

Step 1 - Zero torque spark plug (air tool).
Step 2 - Torque to 16-20Nm final torque, start monitor at 6-12Nm, and final torque must be readed within 3-25 degrees.

I'm not going to go into the why or how much, except to say that regular maintainance, and using anti-sieze on the threads, we've not heard of anyone following this practice lose a plug. 25-30K miles or every 2-3 years to go over every plug, clean, anti-sieze and reinstall/torque is a must.

Ford/Motorcraft's replacement plugs are zinc-plated (galvanized) - to keep the corrosion from building up, and destroying the threads, either when the plug is removed later, or when the corrosion builds up enough to loosen the plug over time.

 

All true, my 2003 Expedition blew a plug, stripped the head and $2700 later it runs ok but I get nervous .Happened when I had a full load of people and had to accelerate hard passing on a hill. Ford needs to reimburse all these peoplefor their misakes..after all "quality is job one"?? yea right.
Time for class action gentlemen.

 

This doesn't make sense to me. How can pressures shoot up when you have a constant compression ratio and fuel/air mass flow. I also never noticed a taper in the spark plugs. I heard that the original factory plugs had less threads, and that they changed to a different plug later to solve this problem.

 

I also have been stung by the escaping plug syndrome 3000 kms after replacing the plugs myself on my 2000 Expy, and after much research on the subject it is my opinion that you must change the plugs when the engine is stone cold and apply anti-seize compound to ensure proper torque. Checking them every now and then wouldn't hurt either (except for your knuckles!)

 

My wife went to move the Expy. so the kids could play in the driveway. Heard a POP! then loud engine noise........just found out...yup, blown out spark plug.

2001 Expy. about 113,000 miles

Oh yeah, about a year and 1/2 ago had the passenger side leaking head gasket fixed......

This motor really, really sucks......