In my 93 Civic with a D16 engine, there is a noise that is somewhere in the engine bay that I cannot pinpoint. I would describe this as a deep whine. The symptoms I noticed are the ff:

1. Battery Voltage (through installed voltage gauge) used to read 13.4 volts with lights and AC on and goes down to 13.2 with the aux fan on. Now, it settles at 12.7 V and 12.1V respectively. These parameters occur when moving, and not stopped in traffic.

2. Oil Pressure--Although I am not certain about the accuracy of my gauge, but at least I use this to set a basis for my readings. It used to read 20 psi at idle with an oil temp of 80 C. Now, it settles at 50 psi at just 70 C.

3. Finally, I notice a "buzzing" vibration in my shifter whenever this sound occurs.

All these suddenly appeared while stopped in an intersection at night.

Electrical grounding perhaps?

Any thoughts or similar experiences? Any suggestions as to what I might have to check?

It is hard to pinpoint the noise with the hood open since all the other ambient noise from the engine drowns this out; it is best heard from inside the cabin.

 

Seems like the alternator is not charging. Is the belt loose and squealing?

 

@ RonJ: The belt is not squeaking and it seems to be that the charging levels are intermittent. Sometimes its normal, sometimes it draws too much electricity. A grounding problem, perhaps? The belt is on tight and its not squealing.

 

If you remove the alternator belt, does the squeaking noise stop? Alternatively, use an inexpensive engine stethoscope to check whether the noise is coming from the alternator (or elsewhere). I am thinking both the noise and charging problem may be resulting from a bad alternator.

 

The noise being louder inside the car suggests it may actually be coming from your stereo speakers. That happens when there is a lot of "ripple" on the electrical system due to bad connections or grounds, bad alternator, or faulty battery.

 

Thanks, guys. It really seems like an alternator problem to me or some electrical issue. I feel more like it is a direct result of a rather deep puddle of water I drove through a few days back.

However, isn't my Check Engine light supposed to light if I have an alternator problem?