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-   -   Exhaust leak from spark plug??? (http://mustangforums.com/forum/5-0l-1979-1995-mustang/711195-exhaust-leak-from-spark-plug.html)

Tasteslikeink 06-22-2014 05:25 PM

Exhaust leak from spark plug???
 
I don't even know if that's possible but it's either the spark plug of the header gasket failed where it had loosened up which just so happens to be right above the #8 spark plug.

The plug isn't loose. It didn't blow out. I took it out to change it and had realized I ordered the wrong plugs and put it back in. Drove it around and then later that night I started it and it sounded like it had an exhaust leak. Brought it to my shop, found 2 loose bolts on my header and tightened them, then replaced all my plugs and wires. BUT THE SOUND WAS STILL THERE!!! Just under load this time. Not all the time. The spark plug wire boot had a light dusting of carbon. I still can't figure out if it's the header gasket, which is what I'm leaning towards, or the plug. It sucks that I have to be driving it to hear it other wise I'd smoke it out! Any suggestions? Also.. How do I find the right timesert or save a thread kit to buy? Thanks in advance. This thing is beating me down.

Tasteslikeink 06-22-2014 05:26 PM

I should add it's a 95 GT vert.

dawson1112 06-22-2014 05:30 PM

Any time the header bolts get loose it will blow the gasket out at that spot. Its almost a guarantee

Tasteslikeink 06-22-2014 05:35 PM

I figured as much. Same mechanic, new car.

mjr46 06-22-2014 10:19 PM

it's a header gasket, it's just that simple, replace it and be done with it..........

Maxwelhse 06-23-2014 12:14 AM

Replace it with a PERCY'S GASKET. Can't say enough good about them.

Wrenchman1 06-23-2014 06:53 AM

hardware
 
Just an added note, Don't reuse the hardware for the header, They are a one time deal.
Never remove hot sparkplugs, The threads can come with them in aluminum.
Not so much cast iron, still a good practice

Maxwelhse 06-23-2014 07:18 AM

Quote:

Originally Posted by Wrenchman1 (Post 8401490)
Just an added note, Don't reuse the hardware for the header, They are a one time deal.

What? I have literally never heard of throwing away header bolts before unless they are corroded (like any other bolt). It seems like my ARP SS header bolt kit would have been marketed as "reusable" (because it is) just like my expensive gaskets.

HEAD bolts get tossed, sometimes.

Wrenchman1 06-24-2014 11:10 PM

torque to yeild
 
Way back when, I attended a GM motor school, We were instructed that any bolt that has a torque spec , is a one time use, Due to the fact that all bolts are an interference fit.
Due to harmonic vibration, They can loosen or not torque correctly.
There was also a tech article written up in one of the mags a few years ago.

bluebeastsrt 06-24-2014 11:15 PM

Well I've never been to any classes but I've been reusing header bolts for ever. I recently put headers on my 2011 Camaro ss and the company that made the headers recomended using the stock manifold bolts to attach the headers. No exhaust leaks on that install. The only bolts that are one time use in my book are head bolts.

Maxwelhse 06-25-2014 04:38 PM

It sounds like GM would have you throw away the entire car during every service procedure (in my experience with their products that might be wise). I mean, the oil plug has threads and a torque spec, right?

Header bolts are so under-worked anyhow (15ft-lbs of torque?) that any argument for metal fatigue (caused by harmonics or thermal expansion) or thread stretch is pretty absurd. I'd have to read the article or attend the class to make an engineering argument about their point, but in this limited case there is virtually no risk of issues resulting from a "failed" bolt. Corrosion kills exhaust hardware which is why I went with ARP stainless hardware when I put my headers on.

Usually when headers get loose all the time there are 2 main reasons: poor quality headers excessively expanding and contracting (thin flanges) working the bolts loose or cheap gaskets that are doing the same thing.

Wrenchman1 06-29-2014 10:58 PM

LOL, And crappy hardware!
Ive had stock factoy header bolts (used) snap. on retorque.
ARP could be a different story?
Just saying, From my experience.
Key hardware, Head, intake, exhaust ect should be replaced.
Do what ya want

Maxwelhse 06-30-2014 03:57 PM

Fair enough. Crap = crap and it's impossible to tell until it happens. Can't lose with ARP.

WJBertrand 06-30-2014 06:57 PM

I know with Toyotas, you can reuse the bolts/studs but not any of the nuts in the exhaust system. Daughter had Paseo that kept blowing the exhaust gasket. Finally broke one of the studs and sent daughter for some new ones at the dealer as I set about removing the broken stud. While there, the parts man informed her not to reuse the nuts so she got new ones of those two. When I looked at the new nuts I noticed they weren't perfectly round - slightly oval. Running them over the studs, which are round, causes interference and keeps them from loosening.

Never had another blown exhaust gasket after that.

Maxwelhse 06-30-2014 10:02 PM

That's a type of locking nut. It would be like re-using a nyloc nut, which you shouldn't. Those ARE only good for 1 use.


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