Chirping noise with rattle

i am getting ready to change belts on a 03 pre runner 2.7L 4Cyl. I have had a loud chirping sound with a slight rattle shortly after startup that comes and goes and is more consistent after running for awhile. I figured it was one of the belts (reason for the change) but after an unrelated issue which was the HVAC control unit taking a dump after disconnecting that the sound has gone away. Any thoughts as to the cause of the problem? I have ordered the new HVAC unit so I am assuming once that is installed the noise will return.

 

Ac clutch really. also sounds like a bad carier bearing but the symptoms are happenjng at the wrong timez. if it happens only when moving, then the cb.

 

OP, are you a regular cab or extra cab?
If a RC, you won't have a carrier bearing. If EC, check the CB as stated above.

Also, check the lower tensioner bearing, under the AC unit as it is typically the 1st of 2 to go.

Good luck.

 

Extra cab - 2WD - opinion on just replacing everything since I am moving in that direction already -- change all the pulleys, fan clutch, A/C clutch -- she has 209,000 on it runs like a champ and starting to do upgrade maintenance to get another 200K out of it.

 

Also, with the chirp noise it did start back up this morning - HVAC control still not connected, thought it was just a random occurrence that it went away for the day since that was disconnected. It isn't as bad as it has been, it happens just after startup and now occassionally while driving. I looked to see the location of the carrier bearing and I don't believe that it is that. The noise is definitely coming from the engine compartment near the fan and alternator area.

 

a bad cb will sound like its coming from the sides and not the engine. So it probably is just a bad velt. They do squeak on revving.

 

thanks for the info with all this, very much appreciated. It does make the noise while in park and idle

 

Turn the car on and spray some water on the belt if it gives away you found your problem

 

Sounds to me like a bad water pump.. To check if it's external or internal, do the belt pull method. Pull one belt off, start and run for a few secinds, turn off, pull the next belt, repeat. If the sound remains after all belts have been removed, then it's internal. Again that's exactly the sound my water pump made though. It would screech real bad upon startup and have a rattling too. When it first started, it would disappear after it warmed up. Then would come and go... I thought for sure it was external related. Until I let it go too long and it locked up on me down the highway.

If it is your water pump, it's getting ready to go any second. And if it locks up, no bueno. Do the belt pull right away.

 

Actually I reread your post and missed the part about the hvac. Sounds like your compressor... If it went away after disconnectimg, that would be the case and not your water pump.. I got ahead of myself. Still a good idea to do the belt pulls tho..

 

Thanks for all the replies, sound went away, not sure what the source was but it had to be either the belts, timing chain, water pump, pulleys, alternator since I just pulled everything off the front end and replaced it. - bound and determined to get another 200K out of it! -- next, plugs, transmission filter change, coil packs, wires and suspension with leaf springs.....$$$$$ wife is more than thrilled with me right now!