exhaust leak?

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THEE_DW
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exhaust leak?

Postby THEE_DW » Thu Jul 25, 2013 12:04 am

Hey so I finally got around to welding up the cracks in my stock headers on my NA. But it still sounds like i have a slight exhaust leak coming from the flange area :banghead: Smog is due soon and don't have the monies for some racing beats yet. Any ideas/tricks to figure it out, i know the small leaks won't prevent me from passing smog, but the sounds bugs me, I have slight OCD with things like this haha.

I thought i could be mistaking the sound with rattling heat shields so i took out all the heat shields as well on the downpipe and no improvement.
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minime
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Re: exhaust leak?

Postby minime » Thu Jul 25, 2013 8:56 am

Is the multi layer metal header gasket in place?
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Re: exhaust leak?

Postby THEE_DW » Thu Jul 25, 2013 9:10 am

minime wrote:Is the multi layer metal header gasket in place?


It was on the studs correctly when I put the header back on lol
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Re: exhaust leak?

Postby THEE_DW » Thu Jul 25, 2013 9:12 am

Is it possible that over torqueing them could create a gap somehow. I didn't torque them down to anything specific, just to what I thought headers should be at
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Re: exhaust leak?

Postby AWDaddict » Thu Jul 25, 2013 9:31 am

THEE_DW wrote:Is it possible that over torqueing them could create a gap somehow. I didn't torque them down to anything specific, just to what I thought headers should be at


Depends on how you put your header back on. If you put it back on with the down pipe attached, there is a chance that it wasn't angle properly when putting the header back on. If that is the case, the firewall side might not be flushed, that's what happened to me.
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Re: exhaust leak?

Postby minime » Thu Jul 25, 2013 10:25 am

Yup, always tighten @ the front of the CAT first, but there is a torque sequence and yes torque value is important. http://www.miata.net/garage/torque.html

start in the middle and work your way out(center first, then nut to the left of center, then nut to right of center, then second nut to left of center, then second nut to right of center, etc). I snug mine up first, then go around with a torque wrench - never had issues with leaks.
'93 black&red LE #1455/1500 "GoKart" aka: MiniMe humping the JDM laser(FOR SALE),'94 white &tan "TheTurd" aka: buttmunched, '93 black&red LE #????/1500 "NoNameYet" VVT swap, NB subframes and drivetrain, '93 White C-Pkg "MiniMe" - track Roid racer(broke), '94 Laguna blue & Tan "P729MX5" FM 1 turbo(parts car) & '91 BRG"TheHULK" my ugly new track monstrosity(work in progress)
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Re: exhaust leak?

Postby THEE_DW » Thu Jul 25, 2013 11:42 am

minime wrote:Yup, always tighten @ the front of the CAT first, but there is a torque sequence and yes torque value is important. http://www.miata.net/garage/torque.html

start in the middle and work your way out(center first, then nut to the left of center, then nut to right of center, then second nut to left of center, then second nut to right of center, etc). I snug mine up first, then go around with a torque wrench - never had issues with leaks.


I put the down pipe on first, bolted to the cat, then dropped the header in, tightened the bolts hand tight so there was play so I could bolt the DP on easier, tighted the down pipe on all the way then tightened down the headers gradually getting tighter as I tightened them all down (similar to the star pattern for lugs)
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Re: exhaust leak?

Postby minime » Fri Jul 26, 2013 7:43 am

Sounds like you did it correctly, but you should probably loosen them all and use a torque wrench. Not sure exactly how to diagnose where it might be leaking(if at all), but I do know that when I use GM top engine cleaner(SeaFoam basically), and run through the top engine cleaning procedure, I see wisps of smoke coming out from around the header flange which means the seal there is not exactly perfect. It has never been enough to cause me to fail smog and I have seen this on ALL of my Miatas when I run through the procedure. What does this mean? fuggifiknow...
'93 black&red LE #1455/1500 "GoKart" aka: MiniMe humping the JDM laser(FOR SALE),'94 white &tan "TheTurd" aka: buttmunched, '93 black&red LE #????/1500 "NoNameYet" VVT swap, NB subframes and drivetrain, '93 White C-Pkg "MiniMe" - track Roid racer(broke), '94 Laguna blue & Tan "P729MX5" FM 1 turbo(parts car) & '91 BRG"TheHULK" my ugly new track monstrosity(work in progress)
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Re: exhaust leak?

Postby THEE_DW » Fri Jul 26, 2013 9:37 am

minime wrote:Sounds like you did it correctly, but you should probably loosen them all and use a torque wrench. Not sure exactly how to diagnose where it might be leaking(if at all), but I do know that when I use GM top engine cleaner(SeaFoam basically), and run through the top engine cleaning procedure, I see wisps of smoke coming out from around the header flange which means the seal there is not exactly perfect. It has never been enough to cause me to fail smog and I have seen this on ALL of my Miatas when I run through the procedure. What does this mean? fuggifiknow...


yeah gunna have to run through it on my next day off, or when i get home from work. Gunna try sea foaming it to see if there are any major leaks. Maybe I'll video the outcome of it and post it up.
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Re: exhaust leak?

Postby Solomon » Sat Aug 03, 2013 6:21 pm

I just got my 1992 NA smogged a few weeks back. Car has 241000 miles on it with stock everything so I'm certain I have a few cracks as well (does sound like I have a slight exhaust leak). I was sent to a STAR station but the tech didn't poke/prod. I passed with flying colors.

If it's relatively small, I'm certain you'll be fine. Just make sure you have the heat shield on there to hide any obvious cracks!

Good luck.
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Re: exhaust leak?

Postby angelcamron750 » Tue Sep 17, 2013 12:59 am

Take it for smog test.

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