99 Expedition #3 Spark Plug destroyed.....

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Jan 9, 2007 | 09:26 PM

WakkoWarner

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99 Expedition #3 Spark Plug destroyed.....

My cousin has a 99 Expedition with the 5.4. We changed the spark plugs (along with all the O2 sensors & the fuel filter) about a year ago. We used the Bosch double platinum plugs with the single ground electrode (the local Ford dealer is trying to tell me that they are not the correct heat range plugs & that could have caused the problem. I am skeptical, as Bosch has been making plugs for a long time & I have never had any problems with them). Recently her husband was towing a heavy trailer & the vehicle started misfiring badly. They took it in & the shop told them to check cylinders 3 & 8. I pulled all the plugs out on the drivers side & the plugs looked good, with number 8 being a little 'whiter' than the perfectly tan color on the others. The ones on the passenger side all looked good - except for number 3. The ground electrode was still intact, but the center ceramic & electrode were completely gone (down about halfway into the hole). I have never seen a spark plug do this before (I don't see a button to upload a pic directly from the computer, so I can't show you the plug). I am worried that the ceramic flying around in the cylinder may have caused permanent damage. I put a new plug in & swapped the coil pack from another cylinder, but it is still missing pretty bad. I am going to install a new coil pack from a different cylinder (we had to replace one & it is on the number 2 cylinder) tomorrow to see if it makes a difference. I know that there have been several reports of this engine family blowing the plug out of the number 3 cylinder due to faulty thread creation at the factory, but I am concerned about what may have caused this problem. If anyone has any ideas or insight, your input is greatly appreciated. Thanks in advance.

Last edited by WakkoWarner; Jan 9, 2007 at 09:29 PM.

Jan 10, 2007 | 07:49 AM

Johnny Langton

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From: SE Texas

Sounds like the plug damage was from detonation. That detonation took out the ceramic insulator when the truck was under heavy load.I've seen them do this to just about any plug,but the Bosch plugs with the superfine center electrode in the ceramic are most prone due to having less metal mass to resist the ceramic insulator cracking.
It's possible that the exhaust valve on #3 has a piece of the ceramic debris lodged in the seat or even worse-it may have cracked the valve or a piston crown. Run a compression check on the engine,and a leak down test to find out if the valves and the piston are still sealing good.
JL

Jan 10, 2007 | 08:26 AM

LxMan1

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From: Louisville,Ky.

I had a Bosch Platium plug do the same thing on my Dad's 89 F150. No towing, no detonation. It fell out and lodged between the piston and cylinder wall. It scarred the cylinder wall enough that it got massive blow-by and loss of compression. I ended up installing a Ford reman. long block.
I always recommend either Motorcraft or Autolite double platinums in the 4.6L and 5.4L engines. Actually in any Ford engine, I use either Motorcraft or Autolite.

Jan 10, 2007 | 01:07 PM

WakkoWarner

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Almost no compression......

We tested the cylinder this morning & it is barely pumping up to 30 (number 2 is pumping up to about 120). So, I disconnected the coil pack & fuel injector - they will have to drive it like that until they either decide to replace the engine or buy a new vehicle. Thanks for your input.

Jan 10, 2007 | 03:56 PM

suzuki0702

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all i can say is wow....30psi...wow

Jan 11, 2007 | 09:05 PM

puppypower

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From: Nottingham, MD

Mines the same way. Same cylinder. Spark plug was blown apart. No compression. I think the exhaust valve is damaged. I haven't checked it out yet. I disconnected the coil and injector also. I just need to find the time to do it. Oh yeah, I was using those stupid Bosch double platniums too. I never had any problem with them on any of my others cars before. These engines are real sensitive. It's ashame I didn't read about the plugs before it happened.

Last edited by puppypower; Jan 11, 2007 at 09:12 PM.

Jan 12, 2007 | 11:11 PM

f2fitty

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Joined: Nov 2004

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I had the same problem with a bosch on #8. Did a compression test and it was 145psi. Truck has a slight miss. I think there is some valve damage. Not looking forward to the repair. Kneeling on the core support to do the will suck. Good luck. Fitty