Solved - Help identifying noise (Battery / Alternator issue)

I'm trying to figure out where this noise is coming from. Tried posting in Technical chat but didn't get much traction over there. I've done a few things already to no avail. I do a lot of off roading during deer season so I really don't want something to break in the middle of nowhere.

This noise started a few months ago and I haven't been able to identify what's happening. It occurs at idle as soon as I crank the truck and I can hear it while driving at slower speeds. At higher speeds it's drowned out by engine and tire noise. It's intermittent and sounds like faint grinding, almost like a computer loading. You can honestly hear it in the cab louder than under the hood. I have replaced the serpentine belt and checked the idler pulleys, that's what I thought it was at first. Checked air filters for debris. Dealer said they couldn't hear the noise but as we all know they are full of shit. Here's a video:


Any ideas where I should go from here? Other than the noise the truck runs and shifts fine. Just trying to figure out if I should be concerned or not. Thanks guys.

 

Did you check heat shields on converter?

 

No but that's a good idea I'll check that today. Thank you.

 

Automatic or manual transmission ?
You can for diagnostic tests , remove the serpentine belt and run the engine for up to 4 minutes .
This is going to eliminate everything that rotates on the front of the engine .

 

Automatic. Thinking it was one of the accessories or idler pulleys I had the dealer check them and they said they were fine. I had them replace the belt since it was off anyways.

 

To me it sounds like an exhaust heat shield like previously said OR a broken catalytic converters inner core.

 

IF you place the shifter in drive , hold the brake hard and give the truck some gas , does the noise increase ?
Try this in reverse as well . Allow the truck to idle afterwards to cool the transmission

 

Thanks guys I will check this after work today.

 

Just tried this. Seems like sometimes a little throttle makes the noise happen faster but not every time. Seems to be intermittent regardless of what gear I’m in. Idling in park it’s just as noisy.

 

If you can get another person to help locate the noise, duplicate condition to make the noise. Have you or other person listen while slowly moving along side of truck from front to back and pinpoint location. If it sounds like noise is from firewall area or further back, turn off truck. Let it cool down. Climb under truck and start tapping exhaust with your fist or plastic dead blow hammer. If it an exhaust shield rattling, put a stainless hose clamp around pipe and shield to stop rattle. Try clamping it first before “ripping it off”. The were put their for a reason and if the manufacturer could save a few pennies on all the vehicles they make, they would have left it off. Hit pipe again to make sure rattle is gone. If the catalytic converters core broke free, you will have to change it to repair it.

 

I would check the skid plates/slash pans under the front, especially if the dealer replaced the belt. I had my transmission flushed at the dealer the other week and 2 days later heard a rattle, turns out they left/lost one the the skid plate bolts causing it to rattle. Just a thought

 

Water pump could be culprit. Also, you can spray wd 40 on each pulley at a time go see if it goes away.

 

Checked the heat shields yesterday and they are all good. I spent a while under the truck trying to locate the noise. Definitely coming from the engine bay, not further back.

At this point I'm thinking the dealer didn't check the pulleys despite me telling them to, and I need to go back and check them myself. I will try the WD40 this afternoon. How would I check the water pump for noise?

 

You’d have to check out the weep hole. If plugged up that may be a sign (it would be all crusted up with solidified pink coolant). Also if you get the serpentine belt off, try to turn the water pump by hand. If it rotates freely, has lots of play (anterior/posterior) or it won’t turn then you have a culprit. It should turn with very minimal resistance. You can YouTube several other Toyota engines and their failed water pump. They all sound the same and are very similar to replace.

 

Spent some time under the hood yesterday. After checking some of the suggestions here I still think it's coming from an accessory pulley. Frustrating...since I asked the dealer to check them for me when the belt was off. Using a long screwdriver I believe I've narrowed it down to the alternator, I'm guessing the bearing in there is going bad. I unplugged it while the truck was running and the noise was unchanged. Can you change out the bearings in these things without replacing the whole thing? The noise I'm hearing is not the typical alternator whine, and it doesn't get worse with a bunch of accessories running...that's why I'm thinking it's just a bearing.

Also I'm planning on removing the brand new belt at some point and checking each pulley myself to make sure I don't have multiple bearings going bad. Thanks for all the help guys!

 

So I've been chipping away at this over the last couple weeks. I used a stethoscope (screwdriver) to track the noise down to the alternator. Not having any issues starting the engine but this morning had a battery warning light upon start up. The night before I was unloading from a hunting trip so just the few minutes of having the doors open the interior lights drained the battery. I let it run for a few minutes and the light went off. I also noticed that the noise started up IMMEDIATELY after the battery light went off.

So I know the battery is at least 3 years old. But could a bad battery make a noisy alternator? Obviously I'm going to get both checked out but I'm concerned about losing power on the highway due to a failed alternator. Possibly both are bad. I know Autozone can check the battery for me but can they diagnose a bad alternator as well? Thanks guys.

 

AutoZone should be able to test alternator. I've had Advanced Auto check one before. Maybe call before you go. Goodluck

 

Just wanted to update the thread in case anyone runs into this issue in the future. The alternator was the culprit. Apparently it had been replaced before with a non-OEM part. The bearings were starting to go bad. Replaced with a reman. Toyota part and the noise is gone.