I have a 2016 Toyota Sienna minivan with about 30,000 miles on it. However, this Sienna was converted to be wheelchair accessible and during this process, many parts on the car were replaced with aftermarket parts including the muffler and the exhaust. For the past 2 years, about once a year, the exhaust gradually gets louder and louder until it sounds like a loud pickup truck. We usually get it repaired but the sound keeps comming back. What do you think it could be and is there any way to prevent it?
What is done to repair it? If they install some cheap metal muffler from China they can rot out in no time.
Look for leaks in the exhaust. A good muffler shop can tell you if it can be repaired or you need to replace it.
Many aftermarket exhaust kits use cheap gaskets between the different sections and are clamped together with several bolt/nuts. The gaskets are cheap and the weak part of the systems. Long time ago I replaced a cat-back system (aftermarket) on my Acura Integra and I was always changing those junky gaskets. I got tired of it and put the system back to stock.
