# Re:

Posted by Will (93 4dsc) on July 12, 2003 at 08:13:20: In Reply to: got a question for those who understand broken studs and symptoms posted by Derrick on July 11, 2003 at 20:17:06: Not completely a noob question, but sort of. ;o) When you have an exhaust leak where the studs are, what happens is that fresh air will seep through the space between your manifold flange and engine. So since our air is oxygen, it will mix with the exhaust gases that are passing through the exhaust system, and when it passes through the oxygen sensor, the sensor will sense the extra oxygen. This in turn causes the engine to run richer (i.e. higher gas:air), causing the engine to use more fuel, and giving you black smoke or causing your tailpipe to soot up. This also shortens the life of your cat because it has to deal with the rich exhaust. Over time, the heat from the leaking exhaust gases will cause the manifolds to warp. If the warpage isn't bad, the gasket surfaces will have to be machined before it is re-installed, so it can mate properly with the engine when it is re-installed. If you've had the problem for a long time, chances are you'll have to replace the manifolds due to excessive warpage. That's the theory, although I doubt that it would play a huge factor in say causing a car to fail emissions. I am going to be replacing my oxygen sensor this weekend to see if my gas mileage improves or not. My broken studs are getting pretty bad themselves. I hope this makes sense. Replys:

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: Not completely a noob question, but sort of. ;o) : When you have an exhaust leak where the studs are, what happens is that fresh air will seep through the space between your manifold flange and engine. So since our air is oxygen, it will mix with the exhaust gases that are passing through the exhaust system, and when it passes through the oxygen sensor, the sensor will sense the extra oxygen. This in turn causes the engine to run richer (i.e. higher gas:air), causing the engine to use more fuel, and giving you black smoke or causing your tailpipe to soot up. This also shortens the life of your cat because it has to deal with the rich exhaust. : Over time, the heat from the leaking exhaust gases will cause the manifolds to warp. If the warpage isn't bad, the gasket surfaces will have to be machined before it is re-installed, so it can mate properly with the engine when it is re-installed. If you've had the problem for a long time, chances are you'll have to replace the manifolds due to excessive warpage. : That's the theory, although I doubt that it would play a huge factor in say causing a car to fail emissions. I am going to be replacing my oxygen sensor this weekend to see if my gas mileage improves or not. My broken studs are getting pretty bad themselves. I hope this makes sense.