Roaring noise from under the hood

[clarrisamel]

I have a 2010 Toyota Prius that when at 2 Battery bars is making a roaring noise, upon acceleration and the RPM's are not showing this noise. When you let up off the accelerator the noise winds down and stops when you come to a complete stop.  Have had it to the mechanic at a dealership several times in the last three years and they have no clue because they can't reproduce it they are telling me.  But this is happening when it is extremely hot out or has been sitting in the sun at the heat of the day.  And once again this is happening when the hybrid Battery is at 2 bars.  

 

 

[Derek.w]

Sound like the generator is working overtime but why has no technician travled with you for a 5 minutes test drive???.

[clarrisamel]

That is the next step I am just now being told.  Thank you for your input!

[TonyHSD]

2 hours ago, clarrisamel said:

I have a 2010 Toyota Prius that when at 2 battery bars is making a roaring noise, upon acceleration and the RPM's are not showing this noise. When you let up off the accelerator the noise winds down and stops when you come to a complete stop.  Have had it to the mechanic at a dealership several times in the last three years and they have no clue because they can't reproduce it they are telling me.  But this is happening when it is extremely hot out or has been sitting in the sun at the heat of the day.  And once again this is happening when the hybrid battery is at 2 bars.  

 

 

Hi, 

Roaring noise does it sound like knocking noise ? What is the mileage of the car? 

[Saxmaniac]

Or exhaust?