@crinkles:
04 Camry 2AZFE typically suffers from the following 3 common problems:
(1) hydraulic strut for the serpentine belt tensioner becomes leaky or the tensioner bearing squeaky, causing it to have cold squeak/squeals. Replacing the unit with a new one (RockAuto sells is for approx. 120USD) solves the problem.
(2)factory water pump weeping hole becomes wet around 60kmiles. This is prolly a water pump supplier/QC issues that can be resolved with a replacement Aisin/factory OE water pump. I got mine done under warranty when you purchase our 04Camry used (bought it through stealership).
(3)serpentine belt groove contamination. With flinging grease/oil from hydraulic strut on the idler tensioner pulley and/or coolant seepage from the water pump, you're deemed to get squeaky in relatively short period of time. While my belt has been replaced along with water pump during factory servicing (part of the agreement for the purchasing of our camry), unfortunately, our 2nd OE factory belt was "punctured" after a road trip to cali due to a jammed piece of rock on the pulley along the highway ride. Bought a new Gates micro-V belt from Rock Auto (25USD), replaced it about 1.5yrs ago and it's been really good since then.
My understanding with this all-in-1 setup using 1 serpentine belt to drive everything is the reduction in complexity required (only 1 belt instead of 3 or more to drive all the accessories, etc.) and that saves a lot of time during factory assembly part. However, it will suffer from catastrophic failure if this very belt snaps on you in the middle of nowhere. My take is to stock up on 1 spare and keep it in your trunk in case of emergencies. Also: as the idler tensioner (for serpentine belt) bearing becomes loose over time, your belt will start to experience abnormal rib wear due to the tensioner bearing wear. When that happens, you shall consider replacing the entire hydraulic tensioner assembly as a whole.
Q.