I have a 2006 2WD V6 Tacoma Pre Runner with 42,000 miles. The truck runs great, but has an annoying noise problem. After I drive the truck about 10 minutes, and slow down to stop or turn, I hear an odd noise that sounds like a rattle and grinding sound mixed together. It is a brief noise and goes away once I increase my speed above 20mph. Sometimes I hear the noise briefly after stopping and increasing the engine RPM. I checked the rear brakes and they are fine, I changed the differential fluid, there are no leaks. I inspected the exhaust system and it seems fine, Using a rubber mallet, I pounded on the cats and muffler and I hear very little noise. Please let me know if you have any ideas on what is causing this problem.
I would suspect a loose shield around the exhaust system. I found one on my 4runner. From talking with my brother in law who is friendly with a Toyota mechanic, it is pretty common with the 4.0 v6. It only happens at a particular rpm. I roll the window up and turn the radio up. Hopefully that’s all it is. The dynamics driving are different then statically inspecting the exhaust system. That it happens after 10 minutes would lead me to believe some expansion from heat is going on before it happens. A Toyota mechanic could tell you for sure and if it is a simple fix. I refrain from doing any welding as a fix as that degrades the stainless steel which could enhance rust formation later. Just my humble opinion.
+1 for dagosa. A loose catalytic converter shield is common on most vehicles.
Just surfing on tube and found interesting rattle fix where someone who had an oil chance done on a Toyota v6 thought the person doing the change might find it easier not to replace all the bolts in the shield you have to remove to access the drain bolt. Interesting how a mechanic can purposely or not…induce rattles and lead an unsuspecting owner back to the shop.