I have a 1983 Jeep CJ-7 with a GM 4 Cylinder Engine and a 5 Speed Manual Transmission. It has no power steering or brakes. It is all original and in reasonably good condition. That means no oil leaks. After the engine has been started and gets warm I hear a chirping sound from beneath the vehicle. I can blip the throttle lightly and it briefly increases in pitch then stops. I can drive it for a few miles and it still makes the noise, but it does not seem to increase volume or pitch with vehicle speed. It does not change when the Jeep is turned left or right. Any thoughts on what might be causing it
I would warm the engine up then shut it off. Remove the drive belts and restart the engine. See if the “chirp” goes away. If it does then check the drive components like the water pump and alternator. It will most likely be a bad bearing.
If the chirp is still there with the drive belts off then you need to see a good, independent mechanic because the problem is internal.
Is the noise present when stopped? If so you might twist/flex the breather and check for a change in the sound. If your Jeep has the Carter 1bbl it is notorious for vibrating the throttle plate screws loose. If that is the problem immediately get the loose bolts coated with gasket sealer and re-installed. One of the screws is positioned so that it can drop into the intake and from there fall into the combustion chamber.