Cracked Exhaust Manifold

T

Titanium-99

Member
:
2007 Diamond Graphite Infiniti G35 Coupe
The other day I took off my heat sheild to polish it up and found that my exhaust manifold is cracked down the center of the manifold. The crack is about 4 inch's long and has two smaller cracks on either side of it. I didnt think much of this because it looked like it was just on the surface and now a week later the car is driving like crap as if it has a exhaust leak. I have checked all the connections on my exhaust and found no leaks , all bolts and nuts were tight. This would leave me with only one conclusion that the exhaust manifold is cracked all the way through and causing the leak. I spoke on the phone with my friendly mazda service dept and explained the situation I also informed him that my car is pretty heavly modded and he said no problem bring it in we will get it replaced under warranty which was kind of shocking to me.So my question to other members is, Has any one else found there exhaust mani cracked? have you taken it to the dealership to get replaced? Does any one know if there is a TSB out for this particular problem? If you have a cracked manifold or have had a cracked manifold please share your story and how it turned out for you.
 
any one got pics of theirs please post them. I will try and get some pics of mine but the car goes to the dealership tommarow. I highly suggest to any one that has not checked their exhaust manifold for cracks that you do so just to be safe.
 
Yeah, i noticed two cracks, but they really only look like they are on the surface. I can't see them going all the way through. Car still drives fine for the most part, and it builds boost and holds it. I will take a pic for you if you want.
 
My stock exhaust had an attachment point that bolted to the transmission. My vibrant didn't have this same attachment - all exhausts on FWD cars IMO should be attached to the transmission.

I haven't had one made yet, but after reading this will be the next thing I do. when you're on the gas, with stock motor mounts the motor moves all over the place front to rear. the flex pipe in the J-pipe absorbs a lot of this movement, and the hangers absorb some. But, there is still flex in the whole exhaust that is transmitted straight to the exhaust manifold. So they crack from the stress, as well as the extra weight of the turbo hanging off the manifold. That's why you want the exhaust attached at the transmission as well - so the piece between the Exhaust ports and the transmission is essentially rigid, forcing all the flex to be absorbed by the rest of the exhaust and the hangers.

This is also an argument for installing AWR motor mounts - they reduce the fore and aft rocking of the engine, so reduce the amount that the rest of the exhaust system needs to endure, and therefore reduces the stress on the exhaust manifold - if your exhaust is not anchored to the tranny...

hope that helps. No pics to share unfortunately.

Edit: i see you have the front motor mount already - the rear is the one that prevents most of the up and down motion of the motor and reduces most of the flex - and adds the most vibration and noise.... but is a decent bit of preventative medicine.
 
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OK dexter in your case that doesn't make sense then... I was thinking more of titanium-99 because he's got the vibrant, same as mine, and it's not attached. stock should be attached at the tranny so there's something else seems to be going on there with you!
 
Welcome to the cracked manifold club.

Mine also cracked, but unfortunately because I was "highly modified" warranty remplacement wasn't an option.

I also agree about mounting the exhaust to the transmission, I had an ION exhaust with no flex section and have no doubt that it contributed to the cracking of my exhaust manny, my exhaust now has a flex section in it.

Damn callaway crap.
 
tiwing said:
OK dexter in your case that doesn't make sense then... I was thinking more of titanium-99 because he's got the vibrant, same as mine, and it's not attached. stock should be attached at the tranny so there's something else seems to be going on there with you!
Click to expand...

Oh! Ah-hah! I think that bracket that attaches to the tranny broke, because I am getting a metallic sound around 3k, and other people have posted its the bracket breaking. So, I think the bracket broke awhile ago, cracked the manifold due to more stress, and now is vibrating at 3k RPM and rubbing against other parts. Makes tons of sense...

And on that note; blah.
 
took the car to freeman Mazda today showed them my CAI, FMIC, Boost Controller, Vibrant exhaust, Defi boost gauge and last but not least cracked exhaust manifold and they said here are the keys to your rental car we will fix that cracked Manifold under warranty. Get a call this after noon, " Adam your new manifold, hardware and gasket have been orderd it will be here on tuesday, wed. at the lastes and we will are looking at slapping it in your car on thursday enjoy the Mazda3 till then"
 
Titanium-99 said:
took the car to freeman Mazda today showed them my CAI, FMIC, Boost Controller, Vibrant exhaust, Defi boost gauge and last but not least cracked exhaust manifold and they said here are the keys to your rental car we will fix that cracked Manifold under warranty. Get a call this after noon, " Adam your new manifold, hardware and gasket have been orderd it will be here on tuesday, wed. at the lastes and we will are looking at slapping it in your car on thursday enjoy the Mazda3 till then"
Click to expand...



good deal... glad to hear.. my maz dealer always ***** me ... dont get me started but im glad to hear that itas just my dealer not all mazdas
 
Titanium-99 said:
took the car to freeman Mazda today showed them my CAI, FMIC, Boost Controller, Vibrant exhaust, Defi boost gauge and last but not least cracked exhaust manifold and they said here are the keys to your rental car we will fix that cracked Manifold under warranty. Get a call this after noon, " Adam your new manifold, hardware and gasket have been orderd it will be here on tuesday, wed. at the lastes and we will are looking at slapping it in your car on thursday enjoy the Mazda3 till then"
Click to expand...
Wow, why can't the dealers around here be that cool.
 
My mani has thin lines like cracks.. I took it to mazda and they said it wasnt covered under warranty.. I took it to another mazda and they said they would cover it but I just havent had time to drop car off..
 
that is exactly what my manifold looked like when I took the heat sheild off except there are two more cracks on mine one to each side of that long center crack. car was running fine when I first found the crack but over the last week it started leaking. The shop forman at Freeman Mazda said he was able to stick a peice of paper all the way into the crack. My boost hasnt been holding all that well lately either spiking and all types of weird s*** not to mention my exhaust is just sounding like s*** lately.
 
If your manifold is cracked and you feel like upgrading instead of just replacing it with stock, what are your options?
Is there anything besides the $900+ MAM turbo manifold?
-B
 
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