I took my 1998 ford E350 van into ford dealer for repair ($1700). One of the spark plugs poped out of the cylinder head (drivers side 3rd back) taking all the threads with it. The service manager said that this happens once in a while. They pulled the head off and sent it to a machine shop where they will install a insert. When I asked him what about the other 7 plugs, will they hold ? He just shrugged his sholders.The van e350 5.4L has 122,000 miles on it, the plugs were changed by a ford dealer at 90,000 . I have been searching for info on how many times this happens, I am starting to suspect that the plugs work their way loose due to engine vibration and the fact that the spark plugs only has 6 threads on it.
I want to explain why I suspect plugs working their way loose. After the new plugs were installed by the dealer the van ran fine ( it ran fine before the plugs were changed . ) 1 year and 25k miles later when the engine is idling I hear one loud tap head sound , It was pretty loud and kinda what you would expect to hear from a old chevy motor. The van was still running great so I looked at the milage (115,000) and figured this motor deserves to have a loud tap head - I'm not going to mess with it. 5k miles later the plug blew out when I started it one morning. by the way, when the plug blew I didn't have a clue what was wrong, I thought a emission sensor on the exaust manifold broke off. I drove the van to a ford dealer and the van ran fine ( except for the loud exaust sound) , I still had no clue the van was only running on 7 cylinders. After the van was repaired I noticed there was no loud tap head sound anymore. So I think one plug worked loose over time.( the loud tap head sound was the plug banging up and down in the threads ) with the plug loose it's very easy to understand how it could blow out taking the threads with it, as the pistion sucks and exausts the loose plug would be like a jack hammer against the threads and it wouldn't be long before that plug would distroy the threads.
The thing I blame Ford for , is designing a van that is just about impossible for a average Ford trained mechanic to change the spark plugs correctly and the spark plug they use only has 6 threads on it so it has to be installed perfectly, and even then it still might loosen up at any time.
Anyone want to email me direct--> donswr@hotmail.com

IF YOU HEAR A LOUD TAP HEAD SOUND COMING FROM YOUR ENGINE WHEN IT'S IDLING... DON'T IGNORE IT !!


Here is a link to more blown spark plug stories:

http://www.f150online.com/forums/sho...5&pagenumber=1

i never heard of that. my ford family hasnt had any problems.

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1999 F-150 AirRaid, 4.10 gears, tint, superchip, see my gallery for more.

This has been a problem on the 5.4 Lightnings. I have read several post stating blown plugs, and that plugs have been loose. I have not change my plugs yet, but need to. I am hoping they wont be loose.

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Jamie

Not the fastest, Not the lowest, Not the loudest, ......what do you want to kick my cat too.........????