Corroded metal is not suitable for welding. Therefore, the service life of a rusty exhaust system after repair is not long. Taped or welded areas usually hold well, but the metal often breaks through near the patch. In systems with multiple mufflers, after replacing the first one, the second one often fails. Therefore, at the service the exhaust system is usually replaced entirely. But this is not always really necessary. Therefore, carefully evaluate the condition of the system parts and decide for yourself whether it is worth changing the entire system or whether you can get by with replacing individual elements. General recommendations for repairing the exhaust system are as follows:
- during the work, the suspended vehicle must be secured absolutely securely, since great effort must be applied when unscrewing it;
- if a connection does not come loose during disassembly, sometimes it has to be torn off by tightening. When assembling, it is better to use new bolts and nuts;
- for reliability, it is also better to replace rubber suspensions;
- if one of the system elements has already been replaced, pipe connections are easier to disconnect when heated. At the service center, a burner is used for this. You can use a blowtorch, but you should have a fire extinguisher ready while working. As a last resort, you can use a rust modifier;
- the pipes must be separated using strong rotational movements or with a hammer;
- if this does not help, use a hacksaw to cut off the pipe of the faulty muffler approximately 10 cm from the connection point. Saw the rest of the pipe lengthwise and press it out with a powerful screwdriver;
- to make it easier to loosen threaded connections later, apply copper grease to the threads during assembly. This also applies to pipe joints.
Information copied from the website MercedesMan