Issue with the 2005-2007 Mustang 3V Spark plugs?
12-08-2012, 11:56 PM
#23
5th Gear Member
Join Date: Jul 2006
Location: New Orleans
Posts: 4,491
The blown-out spark plugs is not a problem with the 3Vs. It was a problem with the 2v 4.6, 5.4 and 6.8 (v10) motors. Ironically, the reason we have problems with spark plugs breaking in the 3v motors can partially be attributed to the "fix" for the earlier blow out problems. The threads were moved further up to facilitate more engagement. Unfortunately, this left a long, easily corroded sheild in a tight spot. I've changed quite a few of these using the TSB method and a lot of patience. Been lucky so far and had no breaks. If you use the proper anti-seize on the electrode shield (NOT on the threads), then you won't have any problems at all changing them the next time.
12-11-2012, 01:48 PM
#27
Join Date: Mar 2012
Location: California
Posts: 7
12-11-2012, 03:05 PM
#28
5th Gear Member
Join Date: Oct 2006
Location: Baytown, TX
Posts: 3,115
Good morning gentlemen,
My dad has had an independent garage for 25 years, and I just discussed the 3 valve 4.6 spark plug issue with him. He sees and repairs a lot of spark plug ports on various motors. However, the early 3 valve 4.6 aluminum heads cannot be fixed once the damage is done. The reason is because the hole was drilled in such a way that only 4 or 5 threads hold the spark plug in place. The result is that sometimes, the plugs are blown out because the threads cannot hold them in. Also, if damage is done to the threads, it often times cannot be fixed except by replacing the head. He said in 08 or 09, Ford fixed this problem. He knows much more about the technical details but unfortunately, I just bought a 2007 4.6 L GT before asking him detailed questions about this motor. I pray to god I don't have any problems with this 73k mi vehicle.
My dad has had an independent garage for 25 years, and I just discussed the 3 valve 4.6 spark plug issue with him. He sees and repairs a lot of spark plug ports on various motors. However, the early 3 valve 4.6 aluminum heads cannot be fixed once the damage is done. The reason is because the hole was drilled in such a way that only 4 or 5 threads hold the spark plug in place. The result is that sometimes, the plugs are blown out because the threads cannot hold them in. Also, if damage is done to the threads, it often times cannot be fixed except by replacing the head. He said in 08 or 09, Ford fixed this problem. He knows much more about the technical details but unfortunately, I just bought a 2007 4.6 L GT before asking him detailed questions about this motor. I pray to god I don't have any problems with this 73k mi vehicle.
No there is no such issue of lack of thread on the 4.6 3v mustang heads.
there is however on f-150's
On 2005 to early 2008 Mustang GT's there are quite a few threads making contact.
12-11-2012, 09:32 PM
#29
5th Gear Member
Join Date: Nov 2006
Location: Alabama
Posts: 2,935
Well, the dealer damaged one of my wheels during a tire installation and the wheel is now discontinued. We came to an agreement that they would change my spark plugs to make up for it.
When I did get a quote for new spark plugs, they said they usually replace coil packs at the same time. I forgot how much they said it would be, but it was somewhere between $400-600. I'm sure if you brought them the spark plugs and didn't want coils changed, it would be a lot less.
When I did get a quote for new spark plugs, they said they usually replace coil packs at the same time. I forgot how much they said it would be, but it was somewhere between $400-600. I'm sure if you brought them the spark plugs and didn't want coils changed, it would be a lot less.