Check your plugs- NOW.

[03SoCalCobra]

I have almost 45k on the 03 now. Problem-wise I seem to be slightly ahead of curve, as problems come up on my car, then shortly thereafter the posts start popping up from other people, so I'll share this one and hope I save someone else the pain. I've now had this happen twice, and after some research find out that i'm not the only one..

http://www.consumeraffairs.com/automotive/ford_spark.html

The first time several months ago I was in my driveway, I start it up to pull it into the garage to do an oil change and after a minute or so of idling it starts running really rough, then loud "POP-POP-POP-PUFFFT-PUFFFT-POP" sounds. I popped the hood, thinking I lost half the bolts in the drivers side exhaust header, but the sound is coming from near the base of the blower...and then I see the plug cover trying to detach itself.

You know those moments in life you always remember- the one where 2 seconds feels like 5 minutes? That was me between the time I put my hand on the plug cover and again on the key to shut it off. :burnout:

The second plug back from the front on the drivers head had backed itself out- completely - and was being held against the open hole by the plug cover and coil pack. The plug was totally shot- the first few threads were smashed, the electrode crushed into the tip of the plug. Keep in mind this is a STEEL plug in and ALUMINUM head. Luckilly, with a little effort I was able to get a replacement plug threaded in and all was well.

I checked all the others- one was slightly loose. I've changed a LOT of plugs in my life- I always do a second re-torque to make sure I don't miss anything. But it's possible..

Several months later, I change the plugs to some NGK Iridiums and guess what- 3 of the old plugs are slightly loose. I know damn well I re-tightened all those plugs after the first one blew out, so now I think i'm loosing my mind. I put all the new plugs in and torque them down- TIGHT.

Fast forward 2 months- pulling in the driveway last night and POP-POP-PUFFFT again, shut it off, pull it apart- same thing, drivers head, front plug this time. Unfortunitly, now i'm SCREWED- the threads are damaged enough that I can't get a new plug in. So today I see if I can chase the threads and clean it up enough to fix it. If not, I have some kludgy or expensive alternatives.

Anyone else experience this? Any suggestions? The only contributing factor seems to be that I started using anti-sieze just before this problem cropped up. :dw:

 

[05 Roush]

I'm having similar problems with fitment. As luck would have it I know it's happening when I lose a pound or two of boost.

At 23K miles I pulled all the plugs and noticed plugs 3 and 6 (not 2 and 7 like I said before. Had the motor reversed) were scored all the way up the threads, indicating sparkplug blowby.

You can torque up the threads as tight as you want and they will still leak/get loose. I've come to the conclusion that I have to retorque the plugs every 3-5K miles.

Is there an anti-seize compound that also seals threads? :read:

EDIT: Oh, and I retorque after getting the block extremely hot.

 

[Twinturbo Ranger]

Surprising. They had this problem with the Lightnings also although it's a totally different head. There just isn't enough threads on the head on the SOHC. I'm going to check mine on the Cobra this afternoon.
Thanks Mike

 

[J15BIG]

With the lightning crowd, nobody uses anti-sieze. I guess thats a no-no on alum. heads?:shrug:

 

[wjfawb0]

I use copper anti-seize on my plugs. I do however check to make sure they are tight every two oil changes or so. I change plugs about every four months.

-Jason

 

[J15BIG]

Just did some research and found that on the Lightnings (can you tell I used to own one;-) ), Ford recommended that anti-sieze NOT be used. I dont know if its the same with the cobras, but just thought I would throw that out there..

 

[SnakeBit]

IMO, Steel plugs threads in an aluminum head and 100,000 miles = plugs that are now "one with the head".

Sorry, but IMO, either use anti-sieze on the threads, or clean and gap your plugs more often than 100,000 miles. I don't know what to make of the loose plugs, other than sloppy QC when the heads were threaded.. This is my second Cobra, and the first one never had even a hint of this problem. The plugs were changed once in 57K miles (at the 27K mark) and came out again at 45K for a compression check. No problems with loose plugs ether time., but a few were in pretty tight and required a good pull to break free from the factory install.

 

[stevieb]

If one is using anti sieze, youre supposed to reduce the torque when installing, even more so on aluminum. It could very well be the threads have been pulled beyond their functionality and lost their clamping force to maintain bolt torque. If Ford said not to use anti sieze, there was a good reason for it. This is what my experience has taught me.

 

[CobraKindaGuy]

What is the recommended torque figures for the plugs and the head covers?

 

[Flatliner]

Very interesting... over the last week, twice I have heard a noise which to me sounds like misfiring, but only after I start the car... now I will have to check my plugs to see if this is indeed the case

 

[NyteByte]

Originally posted by CobraKindaGuy
What is the recommended torque figures for the plugs and the head covers?

Yes, I would like to know this as well. I don't want to put new plugs in and just torque them up by "feel".

 

[TrueBlueGT]

Apparently they misunderstood.....I am back on the phone trying to find out right now.

 

[05 Roush]

Originally posted by TrueBlueGT
Matt @ FordSVT says this is a 6 step operation. Get your pencils out boys.

1. tighten to 30lb/ft
2." " additional 90 degrees
3. loosen bolts minimum of 1 full turn
4. tighten again 30lb/ft
5. " " 90 degrees again
6. " " additional 90 degrees.

He described the procedure for tightening the ten bolts on top:
Tighten in an X pattern starting with the middle 2 first and then work your way to the outside while criss-crossing back and forth over the center two.


There you go. Let's see what happens with this per ford instructions.

That's sounds like the torquing of a head.

 

[TrueBlueGT]

I didnt' think it sounded right, but that is word for word what he told me so maybe he misunderstood the question.

 

[TrueBlueGT]

Okay....here it is. The torque spec on plugs is 11lb/ft.

 

[Top_Fuel]

Originally posted by stevieb
If one is using anti sieze, youre supposed to reduce the torque when installing, even more so on aluminum. It could very well be the threads have been pulled beyond their functionality and lost their clamping force to maintain bolt torque. If Ford said not to use anti sieze, there was a good reason for it.

I remember an instrucor saying something about this in automotive school. GM dealership techs were using anti-sieze...which in itself isn't a bad idea. But people weren't adjusting the amount of torque they used when installing plugs, and they started screwing up heads. Then GM issued a TSB telling people to stop using anti-sieze. I guess it was easier to do that than it was to tell them to go easy on the torque when installing plugs.

-Greg

 

[jedeyeben]

Something like this has been around for a while. My buddy had a brand new motor(warranty issue) put into his 99 cobra. On the way home from the dealer, it blew one out.

Crazy!

 

[05 Roush]

Originally posted by TrueBlueGT
Okay....here it is. The torque spec on plugs is 11lb/ft.

That's the problem right there. Low torque + short thread depth = problems.

 

[ALA G8R]

Originally posted by CobraKindaGuy
What is the recommended torque figures for the plugs and the head covers?

Torque plugs to 15n-m. Torque coil covers to 10n-m. No more.

 

[Davesnake]

I just had a plug get loose on me...cylinder #3. I had NGK IX55 Iridiums in the car. The plugs were installed about 8k ago. scary I will check them at every oil change(3k) from now on.

Dave