Noticing a whine thats pretty loud coming from the engine bay. When I first start the vehicle its pretty loud and will fluctuate and eventually even goes silent. Sometimes if its whining, I can hit the gas and it will stop until the RPM's come back down. While driving I can hear it whine and will change frequency as I apply gas. It comes and goes throughout my driving. After my drive I parked the car in the driveway and the noise was gone and I assume it would start up once I started to drive again. Also, as the vehicle shifts gears you can hear the whine come and go as it goes from 1st to 3rd..

Ive read some other posts about water pumps and Idler Pulleys. I assume I would have to start taking off the serpentine belt to narrow this down, but I wanted to see if anyone else could diagnose this from the way the sounds changes in relation to the throttle. Would both idler pulley or water pump be affected by how much gas is given? Maybe its neither of them?

Any other way to check before having a shop look at it?

Thanks,

I would check out the idlers first as they make noise when they are getting tired but also the alternator can do it. Easiest thing is to pull the belt and spin everything touched by the belt except the crank pulley. Should be no noise, should be smooth and no slop.

All of the items that touch the belt except the crank pulley can make noise that changes with engine speed including the AC compressor. They all have bearings that can dry/wear out. Even a worn out belt can make this noise.

Do a cold start, and one at a time spray wd40 into each pulley bearing Until the noise disappears. Just dont spray the belt. The tensioner pulley seems to fail quicker. You can press in new bearingS 6203RS x2 into the pulley $8 each. All the others have unique bearings. The two upper idlers use koyo 6302RMX $14 each

6203-2RS C3 SKF Double Sealed Bearing 17x40x12 (mm) | eBay

Idler Pulley/Bearing Failure, what to do: | Page 10 | Toyota FJ Cruiser Forum

If it turns out to be the tensioner pulley, you dont need to, and dont want to replace the whole tensioner mechanism. Just replace the pulley. The bolt is reverse threaded on just this one pulley, so the rotation doesnt loosen the bolt. Torque it to 30ft#s. The lower. Pulley is 40ft#s and the two upper pulleys are 29ft#s.

Best bet is to go to the auto part store and for around $10 buy yourself a mechanic's stethoscope and use it carefully to pinpoint where the whine is coming from, everyone should have one in their toolbox!

I had a pretty annoying engine whine for quite a while and decided to replace the idler pulleys as well as the pulley for the tensioner (which I believe was the one making the noise).

Really made more of an improvement than I thought it would. That whine really made the truck seem kind of weak and wimpy and would turn some heads when driving around my neighborhood. Not to mention that first start up without the whine is just a great feeling!

If you've never replaced them I'd definitely start there as they're all relatively inexpensive to replace. Just remember that the tensioner pulley is left-hand threaded so it's right-loose, left-tight

Right!! The noise was so horrible that it was noticible and caught peoples attention. Mine turned out to be a combination of idler pulleys, tensioner pulley and my alternator bearings were shot, that was causing the noise so check that too. Now its quiet and smooth sailing.

I just got this insane whining noise at 9500 miles on the odometer. It is driving me absolutely crazy.