Yesterday morning when I cranked my 98 (TJ 4.0 Automatic), I heard a new sound coming from under the hood. I'm not a big proponent of the "wait for it to break" approach, so I've been trying to track down the source. It's a low hum, kind of like when an AC compressor is engaged. It's most audible inside the cab and it diminishes as the engine warms up. It goes up and down in frequency with the RPMs.
I'm wondering if it's the alternator going bad, but I can't really tell if that's the source or not (I was a drummer for a lot of years and consequently have so-so hearing). The voltage gauge is staying between 12-14V so the alternator is performing okay.
It isn't the power steering pump as the sound doesn't change when turning the wheel.
I recently replaced my heater hoses and had to drain some coolant to do so. I need to get it flushed but I can't do that at home because I live in an apartment. Maybe the water pump is clogged from loose sludge in the system? Would that make it noisy?
My only other hypothesis is that it could be coming from the automatic transmission. I say that because there were some frothy air bubbles in the fluid on the dipstick when I checked it, but just like the alternator, performance is normal.
Maybe it's just worn bearings that will eventually make more noise. Is this actually the time for "wait and see"?
I'm wondering if it's the alternator going bad, but I can't really tell if that's the source or not (I was a drummer for a lot of years and consequently have so-so hearing). The voltage gauge is staying between 12-14V so the alternator is performing okay.
It isn't the power steering pump as the sound doesn't change when turning the wheel.
I recently replaced my heater hoses and had to drain some coolant to do so. I need to get it flushed but I can't do that at home because I live in an apartment. Maybe the water pump is clogged from loose sludge in the system? Would that make it noisy?
My only other hypothesis is that it could be coming from the automatic transmission. I say that because there were some frothy air bubbles in the fluid on the dipstick when I checked it, but just like the alternator, performance is normal.
Maybe it's just worn bearings that will eventually make more noise. Is this actually the time for "wait and see"?