I got my head gasket changed out. I heard the noise the day after but the mechanic said it was normal. I know an engine should probably sound smoother than that. I got my exhaust manifold changed out, water pump, thermostat, timing belt changed out too.
When the exhaust manifold was changed, it is very possible that the heat shield located on or adjacent to the manifold was bent, or was not securely re-attached. Luckily, that type of problem is merely annoying, rather than being a functional problem that will affect the engine or transmission.
This is easy for any mechanic to check by putting the car on a lift. However, that is just a guess from afar, and you shouldn’t allow your mechanic to skate away from your complaint by saying that it is “normal”.
Thank you! I’ll check up on that.
could be a cracked flexplate, they rattle
Check for exhaust leaks too. Rat-a-tat-tat and zooming sounds can be caused by that too. But I think the advice giving by VDC above is the most likely explanation. Check the cat heat shield too btw.