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The exhaust slowly became louder over the last week. It is now sounding almost as open pipes, and i can smell exhaust fumes over the manifold. Does the stock manifold or its gaskets crack easily? 50k miles on the car.

Thank you.
 

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That is a thought. I do have the stock engine mounts and drive on terribly potholed streets and highways. Another thought that has been going through my mind is fuel injection cleaner. The same Lucas brand corroded prematurely a clamp on my other car. I suspect it is not the manifold that is cracked, but rather the manifold gasket.

If it has cracked it is most likely from the excessive engine rocking caused by the soft engine mounts.
 

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Closer than you think
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A cracked manifold should throw a CEL because the O2 sensors will detect the air leak...
 

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No, unless the crack was so big nearly no exhaust was flowing past the O2 sensor it will not notice anything.
I recently had cracked mounting studs on the manifold of my Durango. It let in just enough outside air that the O2 sensors were fried, triggering the CEL. It also seems that the sensors are designed to pick up some pretty subtle differences in O2 flow, and the Venturi effect alone would draw in considerable outside air... That's my reasoning, but then again, I'm not an automotive engineer either.

I have a feeling that I'm about to be proven wrong...:D
 

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German Reimport
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Take the diffuser off and check the exhaust!
There are quite a few known cases of broken "U" tubes between the cat and the muffler.
And the symptoms are very similar to your description.

Broken "U" tube does not only lead to exhaust fume smell but can easily lead to the smell of burning fiber glass :eek:.

I would not drive the car until you checked it
 

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No, unless the crack was so big nearly no exhaust was flowing past the O2 sensor it will not notice anything.
When it sucks in air then the O2 sensor will show lean.
Depending on where the crack is this is a very real possibility.

As was mentioned>
A cracked manifold should throw a CEL because the O2 sensors will detect the air leak...


...Another thought that has been going through my mind is fuel injection cleaner. The same Lucas brand corroded prematurely a clamp on my other car. I suspect it is not the manifold that is cracked, but rather the manifold gasket.
That is unlikely.
I cannot think of what could be in the cleaner that does not reduce to H2O and CO2 just like the fuel does.
 

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I had noticed my stock 2005 Elise sounding louder for a few days; tried to ignore any thoughts that it was due to something bad because it sounded so good... the check engine light came on last night so I had the code read this morning. The rear O2 sensor was not happy. I took off the rear diffuser and discovered the weld just prior to the U-bend of the muffler had completely failed. I am informed that it would be easier to replace the muffler than try to re-weld the stock one. Does that sound right? And would stiffer motor mounts be of help? I drive spiritedly on the bumpy roads of the Central coast of California, and Laguna Seca when my wallet allows.
 

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Travis, Have you considered putting a flexi-joint in there to mitigate the flexing causing the weld to break?
 

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Currently working on removing entire muffler system to take to a shop for welding. Straightened and marked the broken connection; stiffer motor mounts on the way... anyone know what's the best way to remove the second bolt (hard to reach, too little space to rotate wrench) that holds the cat pipe to the heads? FWIW, I am not a mechanic, but I slept in a Holiday Inn Express once (only funny if you remember the ad, sorry).

exhaust 010.JPG

exhaust 028.JPG
 

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flex head ratchet and a bunch of u-joints. Sucks cause usually that bolt will need a lot of torque.

Weld it all back together. The motor mounts will make the car vibrate more, but it will get better after a few hundred miles. I bought mine from blackwatch. Just the front and rear mounts.
 

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u pipe/ cat

I just had the same thing happen to my 2005 elise. THe cat pripe just split all the way around. In NY the manufacturer must warranty the catalytic converter for 8 yrs, check with your state. Mine is being replaced along with all the damage it caused to wiring (melted) o2 sensor, and inner fender liner under warranty.
BTW, Lotus no longer makes or stocks the o2 sensor I am told.
 

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I've had my stainless steel exhaust on my Esprit welded 4 times now for $40 each time at a local muffler shop... Much cheaper than $1500 fora new one...

I would mark the relative position of the parts with a sharpie, and take it in to get it welded at a shop.
Travis,

Is the manifold cracking or elsewhere? I have not had any issues with mine and have not heard of any from any of the others.

Al B.
 

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Al, Holmz,

My exhaust (muffler) has cracked at the hangers a few times. the Original design was crap, so the local muffler guy has fixed it a few times for me.

Original failure

Cracked on the other side as well.

This is a Stebro Dual, and apparently they all fail like this, obviouls why really.

So it recently broke again, past the previous gusset.
So I had the local shop reinforce it some more with some triangulated braces.


I also had him add another O2 sensor bung for my wideband dash gauge.



SO my point was, that stainless is pretty easy to fix... it may not be pretty, but it is weldable and you don't have to buy a new one.

On the other hand my exhaust manifold is cast iron, and that is not weldable... Well, you can try, but the stress concentrations will just cause it to crack more.
And mine has a tiny hairline crack...

 
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