'85 12A Exhaust Issues

Romulan_7 · 11-16-2009, 02:59 AM

My car keeps burning out the collector gasket at the end of the exhaust manifold every couple of months. I'm thinking it's some kind of mixture issue, though I haven't gone through the effort to go chase it, so I'm not certain. I don't have any performance issues other than that, so I'd guess that the mixture wouldn't be far off if I'm right. As far as I know, the car has stock ports, and I know for sure it has a Nikki with the rat's nest intact, with stock ignition except for a couple of MSD coils. I run it on 87 octane without premix with Royal Purple 5W-30 in the sump.

Rogue_Wulff · 11-16-2009, 10:16 AM

If it keeps burning that same gasket, I'd bet the mating surfaces are not true making for a spot that has little tension against the gasket. Either one of the mating surfaces is warped, or the pipe/manifold aren't lining up quite right.
If the gasket is always burning out in the same basic spot, start looking in that area for warped surface(s) or misaligned pipe.

Romulan_7 · 11-16-2009, 12:40 PM

Misaligned pipe would probably be it. My little rubber exhaust hangers are starting to wear out, so the cat/midpipe section is too low.

rx7carl · 11-16-2009, 11:20 PM

Are you using quality gaskets? If so Roger's advice is probably a good place to look.

Romulan_7 · 11-17-2009, 01:41 AM

Autozone gaskets, your mileage may vary. Thicker than the normal piston motor collector gasket with what looks like a metal o-ring around the inside of the exhaust hole.

rx7carl · 11-20-2009, 02:16 PM

I wouldnt trust anything but OEM Mazda gaskets on the exhaust.

1stGenNutt · 12-13-2009, 08:56 PM

just jerk it off and place a header and straight weld it to a pre silencer and a good muff
take the cat to a scrap metal dealer and get some of your investment back

11-16-2009, 02:59 AM	#1
Romulan_7 The Newbie Join Date: Aug 2008 Posts: 12 Rep Power: 0	'85 12A Exhaust Issues My car keeps burning out the collector gasket at the end of the exhaust manifold every couple of months. I'm thinking it's some kind of mixture issue, though I haven't gone through the effort to go chase it, so I'm not certain. I don't have any performance issues other than that, so I'd guess that the mixture wouldn't be far off if I'm right. As far as I know, the car has stock ports, and I know for sure it has a Nikki with the rat's nest intact, with stock ignition except for a couple of MSD coils. I run it on 87 octane without premix with Royal Purple 5W-30 in the sump.

11-16-2009, 11:20 PM	#4
rx7carl Rotary Fan in Training Join Date: Mar 2008 Location: Orlando, Fl Posts: 59 Rep Power: 18	Are you using quality gaskets? If so Roger's advice is probably a good place to look. __________________ www.pbandjracing.com

11-20-2009, 02:16 PM	#6
rx7carl Rotary Fan in Training Join Date: Mar 2008 Location: Orlando, Fl Posts: 59 Rep Power: 18	I wouldnt trust anything but OEM Mazda gaskets on the exhaust. __________________ www.pbandjracing.com

11-16-2009, 10:16 AM	#2
Rogue_Wulff Non Member Join Date: Jun 2008 Posts: 310 Rep Power: 18	If it keeps burning that same gasket, I'd bet the mating surfaces are not true making for a spot that has little tension against the gasket. Either one of the mating surfaces is warped, or the pipe/manifold aren't lining up quite right. If the gasket is always burning out in the same basic spot, start looking in that area for warped surface(s) or misaligned pipe.

11-16-2009, 12:40 PM	#3
Romulan_7 The Newbie Join Date: Aug 2008 Posts: 12 Rep Power: 0	Misaligned pipe would probably be it. My little rubber exhaust hangers are starting to wear out, so the cat/midpipe section is too low.

11-17-2009, 01:41 AM	#5
Romulan_7 The Newbie Join Date: Aug 2008 Posts: 12 Rep Power: 0	Autozone gaskets, your mileage may vary. Thicker than the normal piston motor collector gasket with what looks like a metal o-ring around the inside of the exhaust hole.

12-13-2009, 08:56 PM	#7
1stGenNutt The Newbie Join Date: Apr 2009 Location: Flat Rock Posts: 23 Rep Power: 0	just jerk it off and place a header and straight weld it to a pre silencer and a good muff take the cat to a scrap metal dealer and get some of your investment back