Alternator whine? or idler pulley? or tensioner pulley? Or all of the above?

I've dealt with a whiney 5.0 pretty much since I got it 3+ years ago and lately I've been trying to determine what the deal is. It sort of came to a head the other day when my 4 y/o son made a comment something to the effect of:

"Daddy, I can hear your engine noise" (this from the backseat).

I asked him what it sounded like and he replicate the whine sound I've dealt with for eons. All this time I thought it was the infamous Ford power steering pump, but today I took it to a local shop near my work and the guy offered to bring in a pump and install it. If the whine stopped, he'd bill me. If it didn't....no charge. Sounded like a deal so I took him up on it.

The phone rang a little while later and he advised me that the pump is not the culprit but they're convinced it's the alternator. I scored the Eddie 3+ years ago with only 54,000 km (35,000 miles). As soon as I traded in my old Sport, I swapped out an aftermarket HO alternator I had on the Sport (scored from an EF member). It was never noisy before on the Sport. I'm positive the whine was evident before the swap. Needless to say, I'm a bit skeptical that it is the alternator. Luckily, I do still have the OEM alternator with only 35,000 miles on it if that's the case.

I got home this afternoon and put my newly purchased stethoscope to work. Sure enough, the whine does seem to be coming from the alternator, but after putting the search engine to use this afternoon, it seems that the lower idler pulley and tensioner pulley are often the culprits of the whine as well.

My question is, since the tensioner and idler are so close to the alternator, is it possible that if they're in fact whining, that the sound could reverberate through the alternator? Everything sounds so much louder with the stethoscope so I'm not really sure what I'm listening to, but the whine is definitely picked up when I do test the alternator. I haven't found a safe way to test the two other pulleys and I don't really want to pull the belt.

The shop is ordering me some idler pulleys (upper and lower) and the tensioner/pulley. I figure that it can't hurt to replace them anyhow as preventative maintenance. He told me the bring the OEM alternator to them as well just to test. I'd rather not give up the HO alternator so I'm curious to know about the sound/reverberation thing from the other two pulleys and get your take. I've seen other posts where people replace their alternator and the whine continues. Over and over that lower pulley seems to cause grief for others.

Hopefully I'll finally have a much quieter Ex so that I can finally enjoy my aftermarket exhaust (after 3 years!) With a pending TMH install this summer, I really want this issue licked once and for all.

Thanks in advance.

I would have done the same with the upper/lower pulleys. Not expensive, and if it doesn't fix it, they're new parts, hey? Process of elimination, right?!

...You can pull your serpentine belt and play with all the pulley's...You should be able to find the culprit this way...

...As for your HO alternator, you can usually have it rebuilt locally, and usually have it the next day...There are shops that only rebuild and sell, rebuilt and new alternators...

tbars4 said:

...You can pull your serpentine belt and play with all the pulley's...You should be able to find the culprit this way...

...As for your HO alternator, you can usually have it rebuilt locally, and usually have it the next day...There are shops that only rebuild and sell, rebuilt and new alternators...

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Yeah, I don't want to pull the belt. Last time I did so, it took me hours to get it back on. I'm not the most mechanically inclined.

Good point on the re-build. I'll definitely look into that if it's the culprit.

I'm just curious to know if a whiney lower idler pulley should reverberate through the alternator body. I always thought the sound originated on the alternator side of the car, but three people (2 of them mechanics) were convinced it was the power steering pump.

35Remmy said:

I would have done the same with the upper/lower pulleys. Not expensive, and if it doesn't fix it, they're new parts, hey? Process of elimination, right?!

Click to expand...

Yeah, I decided I'm getting the pulleys done anyhow. I'm hoping that solves it. They'll have my other alternator nearby if the whine does continue.

subscribing.... let me know how this goes... i just replaced my alternator yesterday because i thought it was my whine culprit... nope- but it have to have been making some noise-you can hear the back bearing grind when turning it.... i have 3 more options. that idler pully front top, center. the lower left idler pully, or the tensioner.... the whine started after a deep mud/water encounter

EDIT: i will take a video of my sound tommorow and post it here

patrick112390 said:

subscribing.... let me know how this goes... i just replaced my alternator yesterday because i thought it was my whine culprit... nope- but it have to have been making some noise-you can hear the back bearing grind when turning it.... i have 3 more options. that idler pully front top, center. the lower left idler pully, or the tensioner.... the whine started after a deep mud/water encounter

EDIT: i will take a video of my sound tommorow and post it here

Click to expand...

I scoured pages of archives dating back several years and the lower idler pulley is often the culprit with the tensioner causing some problems too. I've seen a lot of posts where they start with a "faulty" alternator, only to learn otherwise later. With the stethoscope on the alternator, it sure sounds like it could be, but I can't help but think the sound is coming from below.

I'd go with the lower idler first, tensioner second. I don't think the upper is a noise culprit often, but it can't hurt.

I spun the pulley on my old 35,000 mile alternator and it seems to spin freely. I'll definitely update the thread one way or another.

p.s. Jon Smith (aka Turdle) suggested a pulley might be the culprit a month or so ago. He's probably right (again).

ha well my back bearing was making a noise when i stethascoped it.... so i know i have fixed one of my noises

GREAT news for a change.

I went back to the shop this morning after leaving my truck there first thing and he said that his mechanic had to eat crow. The alternator was fine (as I suspected). I played around with the stethoscope for a while last night and I can see why this would be misdiagnosed. The alternator did sound like crap, but it was definitely the pulleys below making the racket (not sure which one).

I had them replace the two idler pulleys and the tensioner and all is quiet! I had a huge grin as I fired it up the first time. I turned off the stereo and drove home for lunch with my windows down. I wanted to hear wha' my Exploder was supposed to sound like.

Once again,bad pulleys are the cause of annoying whine despite the fact everyone had told me it much be the PS pump!

I'm a happy camper.

Bryan's 98 Mounty had the noise. It turned out to be the tensioner pulley.

Turdle said:

Bryan's 98 Mounty had the noise. It turned out to be the tensioner pulley.

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In my case, it could have been too. I'll never really know which one caused the problem, but the advice given on this site often says "replace the lower idler and tensioner". Sage advice Jon (and advice you gave me recently).

Hopefully others will see these threads before they spend the money on a new alternator!

Turdle said:

Bryan's 98 Mounty had the noise. It turned out to be the tensioner pulley.

Click to expand...

New avatar? And yes, tensioner pulleys = the devil. Ok maybe not since they are easy to change. I like the idea about rebuilt alternators, I had a friend who did these and charged $25 each rebuild. He had a supplier that sent him a little kit for rebuilds that had all the brushes, wires and magnets each kit cost like $4.00. Now this was about 3 years ago, but I doubt the kits increased much in price. $4.00 or even $25.00 is better than $150 any day.