on my newly acquired '03 trailblazer i noticed that it has an exhaust leak. i haven't pinpointed where it's leaking from but i have noticed that someone replaced the cat with a piece of pipe so maybe the welds are leaking. I have read alot on here about the exhaust manifolds cracking. how common is this? do they crack on every single 4.2 out there? how would i know if it's the manifold cracked and not just a leak by that pipe that's welded in? It's not a really loud exhaust leak that i can hear. it just sounds like a small hole in the muffler which that may be the issue too. the muffler ends are rusty. also, if my manifold is cracked, what would be the harm if i did not replace it? will it just get worse?
what if my exhaust manifold is cracked
- Thread starter niceguypmp3
- Start date
MANY crack.... but not necessarily ALL.
Investigating exhaust leaks.... SUCKS... and can be very dangerous. That being said, it is certainly doable. With the car running but not necessarily at temp, car in park (obviously) you'll need to get access to the pipe area presumably by laying on the ground next to the car and feel (yes, feel) around the pipe without touching it. If the leak is significant, you'll feel "puffs" of exhaust come out. Before beginning this perhaps survey the pipe area for signs of leakage like carbon streaking and buildup. These are usually the telltale signs of an exhaust leak - feeling the "puff" is confirmation. Exhaust pipes get extremely hot, so use ample caution.
As for manifold cracks... you'd need to remove the heatshield (which can be a real pain) and inspect the manifold for carbon streaking and cracks (engine off and cool). Sometimes the flanges(tabs) of the manifold will break off - this would usually produce plenty of carbon around the exhaust port and manifold. It's also not uncommon for the exhaust manifold bolts to loosen... tightening them carries the risk of snapping them off. So, too, does replacing the manifold itself. It often happens that replacing the manifold results in several broken bolts that are nearly impossible to remove in-vehicle. There are several threads on here that detail removal and replacement of the exhaust manifold. Few jobs suck more.
Investigating exhaust leaks.... SUCKS... and can be very dangerous. That being said, it is certainly doable. With the car running but not necessarily at temp, car in park (obviously) you'll need to get access to the pipe area presumably by laying on the ground next to the car and feel (yes, feel) around the pipe without touching it. If the leak is significant, you'll feel "puffs" of exhaust come out. Before beginning this perhaps survey the pipe area for signs of leakage like carbon streaking and buildup. These are usually the telltale signs of an exhaust leak - feeling the "puff" is confirmation. Exhaust pipes get extremely hot, so use ample caution.
As for manifold cracks... you'd need to remove the heatshield (which can be a real pain) and inspect the manifold for carbon streaking and cracks (engine off and cool). Sometimes the flanges(tabs) of the manifold will break off - this would usually produce plenty of carbon around the exhaust port and manifold. It's also not uncommon for the exhaust manifold bolts to loosen... tightening them carries the risk of snapping them off. So, too, does replacing the manifold itself. It often happens that replacing the manifold results in several broken bolts that are nearly impossible to remove in-vehicle. There are several threads on here that detail removal and replacement of the exhaust manifold. Few jobs suck more.
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