#3 Spark Plug blew out of my dad's 1999 F-150 Lariat 5.4 Windsor engine. He had to be towed home and when we got to looking under the hood, the wire going to the #3 cylinder was vibrating alot. The COP on top of it was broke from the mounting screw. Pulled it off and started it, Motorcraft spark plug flew out. The plug electrode had grounded itself to the top of the plug. The threads weren't pretty and look crossed. The truck has run fine for about 5 years since we've had it with the same spark plugs in it when we bought it. The boot was in horrible shape, so was the resistor inside of it. Anyone ever hear of this happening before? 90,000+ miles. Thanks in advance.

 

Click SEARCH, enter "spark plug blow out" for many previous threads.

To repair click SEARCH and enter "Timesert"

Steve

 

Do the heads need to be removed? Any idea what caused it?

 

Calling all people who have had and fixed this problem.

 

Here is some good reading.

https://www.ford-trucks.com/forums/s...d.php?t=275828

https://www.ford-trucks.com/forums/s...d.php?t=474946

 

That'll do for tonight, thanks.

 

got a 99 f150 4x4 5.4L triton plug blew out. had to retap treads and use a oversizeplug.

 

Just to let everyone know, it is possible to fix this problem with the Big-sert kit from Time-sert. http://www.timesert.com/ My dad's truck is now running.