Spark Plug Problem

[Txfireblade]

I thought I'd share my recent experience relating to the spark plugs in my 2007 Sport Trac 4.6 V8 just in case it helps anyone.

So I'd read about the problems with the 3 valve Ford V8's and how the plugs can become jammed in the heads once the mileage starts to build up. My truck had 43K miles on the clock and so I thought I'd pull the plugs so check for any carbon build up and hopefully prevent them seizing up. I removed the plugs successfully, although some of them were tight ,and I cleaned the small amount of carbon off the plug barrel. The plug gap look to be quite large but I couldn't find the spec anywhere (didn't check the hand book thoroughly enough) so I put the plugs back in (since they're supposed to be good for 100K miles and they can't be adjusted) and went out for a test drive.

I immediately noticed a misfire, followed shortly after by the check engine light coming on. I returned home, checked all the connections etc but the misfire was still there. I picked up a new set of plugs the next day and installed them, and the problem went away. When I went back and checked the old plugs again, I found that they all had started to fail, with the plug body starting to pull away from the center electrode. This is what caused the plug gap to increase when I removed plugs.

So just a word of warning, if you remove the plugs before their due time, expect to replace some or all of them as the removal process alone seems to trash them.

 

[GreenMando]

Fixing something that did not need fixing till it did need to be fixed. Sounds smart. :

 

[eppd00]

There is a thread about the 2 piece Motorcraft plugs and their issues about coming apart during removal. Someone posted a Champion # 7989 plug as being a one piece replacement a while back.

 

[Txfireblade]

There is a thread about the 2 piece Motorcraft plugs and their issues about coming apart during removal. Someone posted a Champion # 7989 plug as being a one piece replacement a while back.

I've read about those but I've also heard that they are a two piece plug as well. A friend who's a Ford Tech recommended using the Motorcraft plugs since they seem to perform better than all the others. The new plugs I got are two versions on from the originals so we'll see how those do in another 50K miles. It's just a shame Ford can't manage to design a spark plug which can be removed without damaging it, or which can result in a $1000 dealership bill for a plug change.

 

[JohnnyO]

My suggestion is to hit the plugs with Liquid Wrench or PB Blaster the night before you plan to take them out. If at all possible, remove them with the engine stone cold.

 

[GSU4x4]

thanks for the heads up, I've got the same kinda truck and probably should look into that soon!

 

[40twist]

removing them scalding hot is how to do it if you can....thats how we do it....they come out like butter

 

[88racing]

Run two tanks of gas each with Chevron Techron before messing with removal of those plugs then crack them an 1/8th turn and let them soak with carb cleaner. Then zip them out with an impact gun.

Upon replacement use Motorcraft plugs for the best results and don't forget to coat the shanks/heat shields with nickel anti sieze.

Using top tier gas also help from carbon build up on them....