do i have a worn idler pulley? or possibly a worn tensioner? I ask because i can hear a sorta "squeaking:" like noise upon cold startup

 

What about the belt? How long or better yet, when was the belt changed?

 

Squeaking is the belt, or in my case was the decoupler pulley on the alternator, which is why I ended up replacing mine

 

im not sure when the belt was last changed. How could I tell if it’s possibly the tensioner or idler?

 

It could just be a loose belt. Do you know how to check for the correct tension for the belt? Google it. Loose belt squeak is different pitch than an idler pulley squeak. Idler pulley squeak is higher frequency than a belt squeak.

If loose, adjust the tension and see if you get rid of the squeak. Good luck.

 

unfortunately i dont have the tools to check so im probably gonna have to go to my shop down the street to have them see what they say, i hope its not the belt as changing these on these transverse mounted engines looks to be a royal pita because of how tight it is down in there. and that means big bucks!

 

FWIW, some belts may slip/squeak, and others may not. After my engine rebuild, the new Bando belt I put on squeaked, but I would not be surprised if a lot of the pulleys had oil/coolant mess on them from the rebuild. After a few drives, I replaced the Bando with a Continental, and squeak went away, been 6 months now and fine. So, maybe some dirt/oil, or old stock vs new stock belt, bit of a mystery, but changing the belt way cheaper than tensioner or pulleys, so start there.

 

Is there a easy definite way to tell a belt “squeak/squeal” from a tensioner squeak or squeal or are they too similar to tell? The area where I hear it coming from is the area definitely toward the front of the engine and it sounds like it’s possibly coming from the area toward the top where I believe there is a tensioner on which the belt goes around?

 

It's actually relatively easy on the RX350. I know you can do it.
The only "special" tools you need that really makes it easy is the serpentine belt removal tool ($14 at Rockauto) and the Belt Hook Tool is nice, too, ($4).

Jack up the front, remove front passenger wheel, remove an access panel cover, then use the tool to release the tensioner and remove the belt.
There are plenty of Youtube videos to show how to do it on the RX. Plenty of diagrams on the internet (and under your hood) how the belt goes on. I suggest you draw your own diagram before you take off the belt to really help you get the idea of how the belt is installed. The thing with serpentine belts is patience and common sense. It doesn't hurt to make markings and write things down to help you re-install the belt the right way. For instance, noticing which side of the belt rides against which side of the front idler, and so on.

Now, when you have the belt off, that's when you reach in there, either from the top or from the wheelwell, and grab each pulley and wiggle and spin them.
And that's how you can check your pulleys and tensioners.

 

If you think about, what you are asking, 'bout a sorta/kinda squeaky noise on start up. One has to think, a belt,can make a squeak noise vs a tensioner or idler pulley, being rubber. A worn bearing on a tensioner/idler would make a grinding type noise. Have you seen or ever heard 'bout a clutch on a alternator for a ISB aka Cummins in a Ram/Dodge p/u? Turn the engine off & you'll hear the belt slipping on the alternator pulley, thanx to the engine stops abruptly. Use a Gates belt......

 

yea it sounds more and more like it is the belt; but i will find out for sure tomorrow when i go and have it checked out,.

 

spray WD-40 on the belt if the sound has gone - tighten or replace the belt

 

Thanks for the replies all I will see what happens tomorrow

 

i went to have my shop look at it; and of course; at the time i stopped there; it wasnt making the noise; it only seems to make the noise upon first startup of the day and until the motor warms up.

 

Sounds to me like a belt.....When was the belt replaced? Use a Gates, a little bit more over the auto parts house brands...