[SOLVED] Serpentine / #2 idler pulley ticking - with audio/video

2014 AC V6 / 6MT 4x4 TRD OR, ~77K on the odo.

New, distinctive & repetitive ticking sound from front end, audio included below. No this is not "Tacoma Tick."

-- EDIT, 2024-03-20 SOLVED this problem by replacing the bearing in the #2 idler pulley above the alternator. --

Sound started within ~1 week or so of my driving at 30mph through 1 foot deep water for a few hundred feet, throwing up tons of water under/around, including covering the windshield completely for a couple of seconds. A flooded roadway, no deeper - this was not a deep stream fording attempt.

Two audio clips follow, one raw/unprocessed with video to show location, the second clip is processed to isolate out the tick/chirp and also show the waveform.

Raw video/audio:

https://www.youtube.com/watch?v=EkEQta2cc9w

Processed audio:

https://www.youtube.com/watch?v=ZHvcPWUR65s

 

Give that fan/water pump a wiggle with the engine off and see how much play it has, that fan looked a little wonky with it running.

 

Sounds like a bearing. Water probably introduced debris into it. Pull the belt off and spin the idler & tension pulleys. Examine the belt too....could be a small pebble in the rib.

 

Yes, do this^^^^^

 

Like Dm93 said, Start grabbing things and shaking.
I too think the fan looked like it was "Unbalanced" in the video.

 

If nothing else run it for a short period with the belt removed. If the noise goes away you know it is one of the driven components.

 

Follow-up:

This noise was caused by the early failure phase of the bearing in the #2 idler pulley above the alternator going bad.

Pressed out the old bearing destructively using a socket & soft-faced dead-blow hammer against the inner race. Pressed in a new bearing using a slightly-janky improvised pressing method, with a large tie-rod end puller tool.

(I would not advise trying to use a hammer-and-socket method to set and press in a new bearing in this case. Too hard to drive it exactly straight into the pulley.)

The puller arms left small dings on the pulley surface, just barely tactile to the fingernail. (See close-up photo.) Smoothed them out a bit with a brass wire bristle brush.

Also changed serpentine belt.

The replacement bearing is a knock-off, we'll see how it holds up.

 

Just following up on this --

That was caused by overlapped rolling-shutter effect from two different LED light sources. Overhead shop light & LED headlamp both have PWM drivers that, in combination w/ the phone camera shutter speed & rotation speed of the fan blades made it appear wonky. IRL it did / does spin true & straight.