Engine Starts Screeching at Low RPM and Continues When RPM is Raised

Question

I have a 2003 Honda Civic D17A1 manual, 202k.

I recently rebuilt my cylinder head and replaced all timing components (the timing belt broke), and replaced a bunch of sensors, vacuum hoses, PCV and IACV, etc. I did the Idle relearn procedure as well.

Now my car idles at around 750 RPM when there is no engine strain, but, when additional engine strain is put on (anything from turning on heat, headlights, defogger, or even cranking the wheel all the way to the side), the engine nearly stalls for a second and a squeaking noise appears.

This squeaking noise continues even when the strain is taken off of the engine and the RPMs rise such as when I start driving (the screech is higher pitched the higher the RPMs). It only goes away once I have been driving for long enough (about 5 min without returning to idle, and the pitch of the screeching gets higher) and then turn off all additional strains on the engine.

The noise does not occur even with all components on as long as they are turned on while driving and the car is not allowed to return to idle, but will occur if the car goes to idle with the strains on it. It doesn't matter if it is idling in neutral or just with clutch depressed, it has the same results.

The screeching noise sounds like the combination of a squeaky belt and the sound it makes when you try to accelerate with the gear shift mostly in first (the gear grinding noise). It is really confusing me as to why this noise occurs or what is even causing it. It only seems to occur after I did the repairs, although this is my first winter with the car. Also, the noise does not appear when the car is warming up and is over 1k RPM.

Any help or insight would be greatly appreciated!

Answer 1

As stated, it definitely could be a belt. It also sounds like the bearings in your alternator are going out. I think it may be a combination of both. Being that the screeching increases when you turn anything on that would pull more power from your alternator, combined with the other symptoms you've stated, the alternator is the absolute first place I would look. The additional drag from a bad alternator would also cause the belts to squeak, too. Take the belt off and see if the alternator pulley spins freely or has any vibration/grinding, or has any play. Even using a mechanic's stethoscope on the alternator while it is running could give it away.

Answer 2

The comment /u/CharlieRB posted is most likely the reason for this squealing.

I would check your serpentine belt for excessive deflection and adjust your Idler and/or Tensioner Pulley(s).