Whine when accelerating

L

LKWJeeper

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2002 Mazda P5
I have a 2002 Mazda P5 with 137k miles. It's in great shape and drives really well.

The only issue is that under acceleration there is a slight whine that follows acceleration. Any ideas on what to check? The belts seem tight and airbox is sealed.

The sound is similar to a turbo whine but I don't have one.


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LKWJeeper said:
Does that require the replacement of the entire alternator?
Click to expand...

It did for me... Some guys rebuilt them .. Parts (bearing) can be hard to find.

(they can be tricky to get apart and back together.)
 
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Sounds like alternator whine. It's usually easiest to just replace the whole alternator.

Also, a bad ground in your audio system can cause whine to come through your speakers. It's not likely to occur in a factory audio system but it can happen when someone installs aftermarket stuff and makes a poor connection to ground somewhere (not grinding off paint/rust, bad crimp on a ring terminal, loose or stripped screw, etc).
 
LKWJeeper said:
I have a 2002 Mazda P5 with 137k miles. It's in great shape and drives really well.

The only issue is that under acceleration there is a slight whine that follows acceleration. Any ideas on what to check? The belts seem tight and airbox is sealed.

The sound is similar to a turbo whine but I don't have one.


Sent from my iPad using Tapatalk
Click to expand...

I used to get that in my protege but it disappeared when I broke up with the missus.
 
Hello, I might have the same problem.

My 2002 Protege5 with 160k miles makes the same noise. It sounds like a whine and is high pitched/annoying. It is extremely noticeable at highway speeds, but is also present at idle. This whine occurs even when the radio is off, and is coming from the passenger side of the engine bay.
Since the discovery of the noise (3 weeks ago) I have gotten a gatorback belt for the alt pulley, and changed the alternator twice.
Through the three alternators, the noise has not changed at all. Ive even tried messing with the belt tension, (loosening the belt to the point of squealing) and it doesnt change the noise.
Another thing Ive tried is putting a long screwdriver up to the individual components attached to pulleys and listened on the other end. The alternator sounds horrible while you can barely hear the power steering, ac, or water pump pulleys.

I was pretty certain it was the alternator. By autozones standards all 3 alternators passed their machine test. The two replacement alternators were remanufactured by duralast. Im not sold on their part quality but its the best autozone could do. When I free spun the alternator pulleys they make a small amount of noise, like a whooshing sound, but definitely not a whine.

Any other ideas as to what could be causing this noise? Or should I just go to a mazda dealership, try to buy an OEM alternator, and hope it works? Getting those alts in and out of the protege5 is a pain. That and im sure the mazda dealership is going to charge at least $300 for a new one. I dont mind the cost, but I also dont want to waste money buying another alternator and having it still make the noise.

Because it occurs at idle, I dont think the noise is coming from the gears in the transmission. Then again, I am pretty new to working on cars

Thanks,

Mike
 
DrMikben said:
By autozones standards all 3 alternators passed their machine test. The two replacement alternators were remanufactured by duralast. Im not sold on their part quality but its the best autozone could do. When I free spun the alternator pulleys they make a small amount of noise, like a whooshing sound, but definitely not a whine.

Any other ideas as to what could be causing this noise? Or should I just go to a mazda dealership, try to buy an OEM alternator, and hope it works? Getting those alts in and out of the protege5 is a pain. That and im sure the mazda dealership is going to charge at least $300 for a new one. I dont mind the cost, but I also dont want to waste money buying another alternator and having it still make the noise.

Because it occurs at idle, I dont think the noise is coming from the gears in the transmission. Then again, I am pretty new to working on cars

Thanks,

Mike
Click to expand...

Pep Boys and AutoZone don't have the greatest quality parts. I usually order from rockauto.com but that can be a pain if there is a core charge. You usually have to ship the part(s) back at your own expense to recover the core charge so you have calculate the $20 you're going to eat into the final cost. I've had luck with Advance Auto when I buy locally. They have the name brand stuff like Moog, Warner, Monroe, etc. I think you should be able to get a name brand re-manufactured alternator for about $175-$200 online or locally.

I'm not a pro either but... Alternator whine is pretty distinct, you know it when you hear it. It's not always caused by the bearings. The diodes can fail and somehow cause the noise. You can try unplugging the multi-pin connector on the alternator while the car is running and have a helper rev it to see if it makes any difference. I'm fuzzy on this so Google it to get a better explanation of diagnosing bad alternator diodes. The battery will power the coils and keep the motor running for 10 minutes or so. Obviously you need to be pretty careful if you're under the car when it's running so use wheel chocks, jack stands and have a helper. Look into auto stethoscopes or mechanic stethoscopes. They're only about $20 and they work pretty well. The screwdriver trick (or wood dowel) works but when you turn your head to put your ear on it, you take your eyes off the work and you could end up accidentally putting the tip of the tool into a moving part and have the thing come back at your head with some force.
 
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Well I figured out what it was at least the car told me when the timing belt snapped.

$500 later no more whine


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mine whines only when cruising at certain speeds. both of my proteges do this.
 
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