Are the spark plugs in the GT a time bomb waiting to happen?


H

HHGT

Guest
While on another forum, a thread got started questioning the upgrade from a Z06 to FGT. Supposedly by a guy in Huntington Beach California - I know it's not you Dennis since your car is in for the half shaft repair. In any event, one of the guys posted a response with a potential problem waiting to happen in the GT.

This is what he states: "Wait til they get some miles on them" he went on to say;

I sold my '03 Cobra with 28,000 miles on it to my buddy in April after buying my C6Z06. He put another 3,000 miles on it and loves the car. However, he recently had a mishap that is going to cost him a bundle and had necessitated the replacement of the motor.

What happened is that a spark plug came loose and worked completely out of its hole in the cylinder head. The constant bouncing up and down, caused by the up and down stroke of the piston, broke all of the porcelain off of the plug (top and bottom insulators) and the lower electrode broke off as well. All of this debris was sucked back into the engine and severely scored the cylinders and damaged the top of the piston. A few of the other spark plugs were finger loose!

It turns out that this is a known problem on the 4.6L and the 5.4L supercharged engines and gets worse with increased boost or NOS. By the way, my buddy's car has neither increased boost nor NOS. Apparently, this problem relates to the small number of threads in the plug holes and the low torque specs due to aluminum heads.

Some of the guys on the SVT forums recommend checking plug torque every couple thousand miles. The FGT could very easily begin suffering from this issue once they rack up enough miles and/or get modded with pulley upgrades and increased boost. END OF QUOTE.......

Attached is the picture he posted.

Any previous Cobra SVT owners that have heard of this and has anyone checked their plugs? Any service bulletins?
 

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BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
I doubt if this conclusion is true. If the plugs are properly torqued they should not come loose from "normal" cylinder combustion pressures. Now if you have some detonation that might happen, but it is more likely you will damage a piston first.

Most likely the plug wasn't torqued properly, too much or too little, or that the plug or head was defective.

But it will be a good thing for us to check the torque on the plugs as well.

BlackICE
 

Red Rocket

GT Owner
Aug 31, 2006
410
Pacific North West
HHGT, thanks for the advisory. I know you are not sounding an alarm, as much as bringing this to the attention of the community. That's worthwhile and welcome.

Back in the 1970's those of us just getting our first cars, at least the ones who liked cars in the first place, didn't just drive them. We had the hood up on weekends and we wrenched them. I can recall having lots to do on my first Tiger - not because I had to, but because I WANTED to. I checked every nut and bolt. I gapped and re-gapped the sparkplugs. I set and re-set the hydraulic lifters. I set the timing every weekend for fun (without using a timing light I might add, an old trick).

Funny thing, when my Tiger or 69 Z28 would backfire through the carbuerator and catch fire, I never once thought of starting a class action lawsuit against GM or whoever. Is this what those damn litigators have brought people to? Curses on them and their ill-gotten gains!

I guess as cars became more reliable and were managed by computers some people lost that interest in their cars. So when I read this post about sparkplugs I thought - why is it different today? Granted there is some real trepidation about over-tightening anything on an aluminum head or block. One has to be careful, certainly. But why is it all of a sudden a "big problem" that <some> owners should look to Ford to "fix"? Especially something as trivial as sparkplugs? Hell, I am grateful to HH for bringing this up, because now I have something else to check on a regular basis, which just increases the attachment to the car. But it's nothing I would ever dream of getting rankled with the manufacturer about. I'm thankful that the access to the engine bay on a GT is so good that it's no problem to work on it.

Hats off to the engineers! Ladies and gentlemen, if you drive 'em you gotta wrench 'em (or have someone do it for you). :thumbsup
 
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Beach-GT

GT Owner
Mark II Lifetime
May 8, 2006
887
Seminole Florida
It's always something. :eek
 

66GT40

GT Owner
Mark IV Lifetime
Dec 18, 2005
32
This is known to be a problem in the Cobra although in my son's car which for a while was running over 900 HP @ the crank and is now running about 600 HP at the wheels without a problem. A friend of his with a Cobra who is running a 200 shot of NOS has not had a problem. The 200 shot has been on board for over 2 years. However a friend from SoCal just blew a plug out of his Lighting and I haven't heard what the damage is.
Jerry
 
H

HHGT

Guest
Red Rocket said:
HHGT, thanks for the advisory. I know you are not sounding an alarm, as much as bringing this to the attention of the community. That's worthwhile and welcome.

Back in the 1970's those of us just getting our first cars, at least the ones who liked cars in the first place, didn't just drive them. We had the hood up on weekends and we wrenched them. I can recall having lots to do on my first Tiger - not because I had to, but because I WANTED to. I checked every nut and bolt. I gapped and re-gapped the sparkplugs. I set and re-set the hydraulic lifters. I set the timing every weekend for fun (without using a timing light I might add, an old trick).

Funny thing, when my Tiger or 69 Z28 would backfire through the carbuerator and catch fire, I never once thought of starting a class action lawsuit against GM or whoever. Is this what those damn litigators have brought people to? Curses on them and their ill-gotten gains!

I guess as cars became more reliable and were managed by computers some people lost that interest in their cars. So when I read this post about sparkplugs I thought - why is it different today? Granted there is some real trepidation about over-tightening anything on an aluminum head or block. One has to be careful, certainly. But why is it all of a sudden a "big problem" that <some> owners should look to Ford to "fix"? Especially something as trivial as sparkplugs? Hell, I am grateful to HH for bringing this up, because now I have something else to check on a regular basis, which just increases the attachment to the car. But it's nothing I would ever dream of getting rankled with the manufacturer about. I'm thankful that the access to the engine bay on a GT is so good that it's no problem to work on it.

Hats off to the engineers! Ladies and gentlemen, if you drive 'em you gotta wrench 'em (or have someone do it for you). :thumbsup

Amen Red Rocket! That was the sole purpose of this post, Forum Community Awareness. In fact, I am taking my 10 & 8 yr. old sons outside to explain what a spark plug is and why tightening things make sense.

Word of the day; Make sure they're TIGHT!!



Sam
 
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isaakgt

GT Owner
Mark II Lifetime
Dec 20, 2005
691
Central CA / Boise ID
I spend more time wrenching on my car than I do driving it. I guess it's like having a form of OCD. I just love tinkering and checking things. The GT is a form of sanity therapy and I enjoy the heck out of it. I guess I'll head to the garage and check the plugs. C ya :biggrin
 

AJK

GT Owner
Mark II Lifetime
Jul 12, 2006
329
What is the spark plug torq spec for the Ford GT ?
 

isaakgt

GT Owner
Mark II Lifetime
Dec 20, 2005
691
Central CA / Boise ID
AJK said:
What is the spark plug torq spec for the Ford GT ?


The manual says to torque the sparkplugs to 13 ft/lb.
 

LEMANSZ

Gt Owner
Jan 11, 2006
601
SoCal
..the sky is falling...the sky is falling...
 

AMB

GT Owner
Aug 29, 2005
401
San Diego,Ca.
GT Spark Plugs

ALL Ford 4.6L and 5.4L up to 2005 HAVE Spark Plug Problem, BECAUSE they ONLY have "4" Theads holding them in !! In 2005 Ford CHANGED the Mustang Cobra 4.6L, the Ford GT 5.4L and in 2006 the Shelby GT 500 5.4L HEADS!!!
The NEW heads have "7" THREADS holding the spark plugs in.

AMB
 

gtjoey

Keep Smiling - GT Owner
Mark IV Lifetime
Oct 14, 2005
3,453
GUYS IM NOT USUALLY ONE TO COMPLAIN :biggrin ,OPINIONATE :biggrin , OR BEGRUDGE SOMEONE OR SOMETHING , BUT HOLY SH#$@T THIS THREAD MAKES THE HALF SHAFT AND DBK GETTING MARRIED THREADS LOOK LIKE THEY MAKE SENSE...... LETS ALL FACE IT THE GT IS JUST THE TITS, THE REAL DEAL, THE GTJOEY OF GTJOEYS :biggrin .SO EAT SOME TURKEY LOOSEN THE POLYESTER PANTS,TAKE A DEEP BREATHE AND DREAM OF BONY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ALL DAY!, I MISS YOU BONY,BONYYYYYYYY :thumbsup GTJOEY JUST HAPPY TO BE DRIVING ONE OF THE GREATEST HOT RODS WITH THE LOWEST TSB'S :biggrin EVER MADE. FREDDY PASS ME A DRUM STICK BABY!!!!!!!!!!!!!!!!!!! NO NOT THE BLONDE FROM THE PICTURE. :biggrin GTJOEY 1314 WILLING TO BUY ALL DEFECTIVE SPARK PLUGGED GT;S FOR 30,000 OR LESS :thumbsup
 

isaakgt

GT Owner
Mark II Lifetime
Dec 20, 2005
691
Central CA / Boise ID
I ain't worried about it. I'm having too much fun. Heck, my '04 F-250 Diesel has had more issues in 2 years than my GT will ever have. :willy
 

LEMANSZ

Gt Owner
Jan 11, 2006
601
SoCal
some of you guys sound like a bunch of old ladies...just get out and drive the damm thing and stop worrying about everything possible neagative occurance that could happen...jeez
 

jasper

GT Owner
Mark II Lifetime
May 17, 2006
138
australia/ 51st state
it's thanksgiving and i aint got a turkey :willy



happy thanksgiving to all
 
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MAD IN NC

Proud Owner/ BOD blah bla
Mark IV Lifetime
Feb 14, 2006
4,207
North Carolina
GTJoey recognized the DBK getting tied thread :cheers (which will be stronger than three - four threads of the Cobra) :banana
 

isaakgt

GT Owner
Mark II Lifetime
Dec 20, 2005
691
Central CA / Boise ID
jasper said:
it's thanksgiving and i aint got a turkey :willy



happy thanksgiving to all



How are those kangaroos for eating. The brown snake is suppossed to taste like chicken. At least you have a few options. You all have a wonderful thanksgiving down under. :cheers
 

jasper

GT Owner
Mark II Lifetime
May 17, 2006
138
australia/ 51st state
isaakgt said:
How are those kangaroos for eating. The brown snake is suppossed to taste like chicken. At least you have a few options. You all have a wonderful thanksgiving down under. :cheers


yep snake tastes like chicken,

roo's no good full of worms. :ack
 

Neilda

GT Owner
Oct 19, 2005
3,559
London, UK
DogFound.jpg
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MAD IN NC

Proud Owner/ BOD blah bla
Mark IV Lifetime
Feb 14, 2006
4,207
North Carolina
Neil - is this the picture?

The Plugs - the Plugs!
 

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