To the Doctor:
I have an automatic 1993 Saturn SC, and for the past couple of months it has been making clicking or popping noises whenever I put it in drive or reverse. It worries me, but I was told that it was just some electrical indicators or something that makes the car shift gears. I am not sure, and it scares me whenever I hear it. It seems like when it is hot outside it gets louder. If you have an answer for what could be causing this, please reply back. I would appreciate it!

Hannah, via email

The Doc Says:
Noises coming from an automatic transmission could mean a number of things. As long as the car is operating well (not stalling, not hesitating or jerking between shifts, etc.), it's likely that the problem isn't too serious, just a noisy inconvenience. While it's impossible to know for certain what the noise could be (it's likely you'd have to take the car to a mechanic or technician to get a definitive diagnosis), from your description it's likely one of two things:

1: A problem with the shift interlock mechanism, the system that prevents you from shifting into gear (either Drive or Reverse) unless your foot is on the brake. To test this, we recommend going to a parking lot or other well-cleared area, putting the car in Park, engaging the emergency brake, then trying to shift into gear without stepping on the brake. If you can do this, it means the interlock mechanism is not functioning and you will need to exercise caution whenever you put the car in gear.

2: A problem with the constant velocity (or CV) joint that mesh your car's half-shaft (or axle shafts) and front wheels. Over time, especially when the plastic or rubber boot that surrounds and protects the CV joint wears, these joints can loosen due to wear, debris or other factors. When this happens, you often hear a "clunk" or "click" coming from the front of the vehicle whenever it's put in gear. If they're not repaired, the CV joints may eventually fail and leave your car without power.

Again, without a physical inspection, it's impossible to know for certain if one of these is the correct diagnosis, but as long as the transmission appears to be operating normally, the noises may simply be a symptom of your car's advancing years.

The advice described above is for informational purposes only. It cannot and should not be used in lieu of an actual, physical inspection and diagnosis by a trained mechanic or automotive technician. The opinions and advice offered herein are not intended to diagnose automotive problems or component failures; they are simply intended to provide information on what could be transpiring. VehicleMD accepts no liability resulting from actions taken as a result of this advice.