Third Gen Prius rattling noise when accelerating/low speed

[DylanB]

This is my first time posting so apologies if I mess something up.

Recently it has started to make a sort of rattling sound when accelerating/at low speeds. The sound seems to be coming from under the car. I'm fairly new to working on cars and wanted to know if anyone might have an idea as to what it could be.

Any help would be greatly appreciated!

[Bper]

Hi Dylan,its likely that it may be something simple like loose exhaust components which is a common problem in many cars, including Priuses. Check for loose hangers, damaged pipes, or a failing catalytic converter. However there are a few other issues that may also cause this so I have also included these.

Worn engine or transmission mounts,these worn mounts can cause the engine/transmission to move more than usual, creating a rattle.Heat shields,these metal shields protecting parts from engine heat can become loose or damaged and start to rattle. Hybrid Battery issues, less common than exhaust problems, but a loose component or internal Battery issue could cause rattling especially unlikely if the sound is metallic. Listen carefully and pay attention to where the sound originates and if it changes with speed or engine RPM.Look underneath the car for loose or damaged parts, focusing on the exhaust and engine mounts.Carefully tap components with a rubber mallet if you have one to see if it replicates the rattle.If you are uncomfortable checking these yourself then I would take your Prius to a mechanic, preferably one familiar with hybrids. While the above reasons for rattling apply, a mechanic familiar with Prius systems might be best suited to diagnose and potentially fix the problem, especially for the hybrid-specific possibilities.Hope this helps.

[TonyHSD]

Hi, 

this sounds like exhaust brackets broken. You need to look all along the exhaust pipes , find the broken bracket and fix it , either welding or with clips. Here an example.

 
 

Other possible rattling noises may come from exhaust heat shielding, again all along the pipes.