My 97 Nissan pick up, 2.4L I4, 5 speed 182k miles has developed a screeching sound for about 15 to 30 seconds after starting. It sounds like a loose or slipping belt. I have replaced all three belts and the tension is right.
I pulled all the belts again and put them back on one at a time and determined that the belt for the water pump and alternator is the source. I checked all pulleys and components and cannot find anything with abnormal drag or roughness or noise.
I though maybe that I might have put too much tension on the alternator belt and maybe put to much side load on the alternator bearing so I loosened it slightly and that just made the screeching last longer. I also noticed that the duration of the screeching is extended when there is a load on the alternator, such as the blower motor or the headlights.
Once the screeching stops, it does not come back even with sudden changes in rpm or changes in load, i.e. blower motor or headlights, however, every time the compressor kicks on, there is a chirp. Before I replaced all the belts, the compressor belt was slipping on occasion and every time the compressor kicked on, it would screech for a few seconds, but its not AC weather right now.
I pulled off the alternator today and took it up to be tested to see if it would screech on the test set, not a peep and passed all tests. BTW, I am not having any issues with charging or starting, the battery is good. I did notice a wire bundle that runs under the air cleaner has abraded and one wire is bare, I’ll address that tomorrow. I don’t see any evidence of shorts in the bundle, all the abrasion is on one side and only one wire exposed, and it only touched plastic as far as I can tell.
Also, I cannot visually detect the slipping, the belt and the alternator appear to be moving smoothly, same with water pump, but its hard to tell because everything is spinning so fast. also, it is not bad if you just do a restart after driving, is will only screech for a second or two, but if it cools down, than it back to the 15 to 30 seconds of screeching, and its LOUD.