Trying to figure out what could be causing this issue with respect to a 2004 Lexus GX470. The vehicle has been sitting in the garage, turned off and stone cold, for over 3 days, so this is not an issue with the normal or abnormal sounds that occur when the car is running or right after it is turned off.

The sound is not really a ticking or popping sound but it is more the type of sound you would get if you tapped a hammer on wood. It is rhythmic and continuous - a little over 3 sounds per second (about 200 per minute) evenly spaced, such that if you set a metronome to 200 beats per minute then it would mimic the sound.

There is an issue with the battery. It was replaced about 3 weeks ago and now the new battery has run down to the point that the car won't start. However, the new battery still has enough energy to light up the dashboard when you turn the key to the "on" position. (The battery was old, and this is a car that my son drives and he wasn't close by when the car died, so I told him to just have AAA replace the battery when they came, meaning that there hasn't been a test of the alternator, etc. yet). But to be clear, this sound is happening when the car is just sitting in the garage by itself, without the key even being in it.

Main concern is what could be causing this sound, followed by a concern that it could have something to do with why the battery drained.

Thanks for any help.

 

Bad alternator bearing?

In any case, diagnosis over the internet isn't going to work. So you'd best schedule a visit with your mechanic/dealer.

Chip H.