Failing Alternator Symptoms? (1 Viewer)

[04UZJ100]

My truck was going to hit 150,000 flawless today miles until this morning when I turned it on and heard a slight whine from the engine compartment. I think I may have a bearing on the way out. I don’t think it’s a vacuum leak because it’s not pneumatic or a “hissing” sound and the truck idles fine.

The faint whine sounds like a noisy power steering pump; however, it’s always there (in gear/park) and changes with RPM. It’s faint and can be heard better inside the car than out with the hood open. My initial thoughts are the alternator or some rotating pulley/accessory on the serpentine belt. The water pump, serpentine belt, tensioners, and idlers were all replaced at 92k. The alternator is original and I do have an aftermarket stereo that could have shortened the life of it. I imagine increased electrical draw would increase the load on the bearings.

Any thoughts?

Update 1

Did some testing on the way home. Headlghts, stereo, and fan on high. Voltage on my scangauge dropped to 11.1V. Battery is 20 months old and I don't think I've ever seen it that low in gear at idle. Also failed an O'Reillys alternator test.


UPDATE 2

Drove 25 miles home. The voltage is back to normal and the noise is 99% gone.

Any thoughts on what could have caused the intermittent noise and voltage srops? Should I drive it as normal? I was going to drop it off at the dealer but now have second thoughts.

 

[ponytl]

could be as simple as the belt, but all the things you listed could be the cause... it change with rpm which would be my first question and points to all things listed.... harbor freight sell a stethoscope for the exact purpose of tracking down such sounds (less than $5) I'd start with rubbing a bar of soap on BOTH sides of your belt.... (always go with the cheapest fix first) but @ 150k it could be alternator time anyway... with the power steering pump the sound would usually change as the pump is loaded (wheels turned side to side) you now have 60k on all the replaced parts at the time of the belt change so? any could be the culprit ... but I always check the simple first...
good luck
p

 

[04UZJ100]

Did some testing on the way home. Headlghts, stereo, and fan on high. Voltage on my scangauge dropped to 11.1V. Battery is 20 months old and I don't think I've ever seen it that low in gear at idle.

Any thoughts if that's on the low end of normal?

 

[04UZJ100]

Just faild an O'Reillys alternator test. I assume those are believable? This is going to be a dealer job.

 

[04UZJ100]

Drove 25 miles home. The voltage is back to normal and the noise is 99% gone.

Any thoughts on what could have caused the intermittent noise and voltage srops? Should I drive it as normal? I was going to drop it off at the dealer but now have second thoughts.

 

[SS100]

Did you check if the battery is good? I used to have an aftermarket MeenGreen alternator on my 80 that made a screeching sound when the battery was dead. (It was a separate battery-alternator setting for my fridge, I could still start the engine with the original battery & alternator)

 

[04UZJ100]

Battery is 18 months old and sits at 13.0V while the car is off. It measured 13.4V while running.

I took it to Toyota and they recommended waiting.

Do alternators slowly die? I figured it would be progressive and not sporadic like what I saw today.

 

[hkeller]

I would guess idler pulley.

 

[ponytl]

I'd be on ebay and ordering an alternator I have had good luck with the most inexpensive ones, you can check the threads here pretty simple couple hour job basic tools... alternators are 3 phase and they can perform"ok" if just one phase is screwing up... they can even check good sometimes...