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My daughter drove her 2012 Elantra Ltd. home from out of state college yesterday. Upon pulling into driveway I hear a noticeable rattling sound from the car. I ask her how long has the car been making that sound? Her response was "what sound" ??

So today I try and localize it. It's worse when engine is at slow speed idle and then diminishes as you rev up the engine. Driving the car it is not noticeable.

The sound is like jiggling a tin can with some small nuts inside, kind of a metallic clanging sound. I used the old trick of using a wooden dowel to the ear and pressing the other end against various parts of the engine. It is definitely loudest and most prevalent when connected to the alternator.

I have an 8 a.m. appt. at the dealer Monday morning as the car has an extended warranty that is still in place. I am just curious if any others have had an alternator failure with this rattling sound being the first symptom?

I really hope it is not a timing chain tensioner or the common Elantra rod knock starting to develop. Car is at 55k miles.
 

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the all too common rattle sound....which leads to the all too common engine replacement. that means there are metal pieces now in your oil pan and engine. Change the oil, look inside the old oil and pan and see if you have shiny metal pieces.. if so, not good.
 

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Just returned from the dealership. My suspicion was confirmed as the tech diagnosed source of rattle with his stethoscope to be alternator bearings. New OEM alternator installed and out the door in under 2 hours total time from drive up to drive out.

OEM alternator $454.63, Labor $266.00, Tax $31.82 = total repair bill of $752.45. Fortunate for me I had a 3rd party VSC (vehicle service contract, aka extended warranty) from Aeverex that totally covered the repair less a $50.00 co-pay. So my $1300 I paid for this VSC has returned over half and I still have 35k miles or 27 months left before it expires.
 

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the all too common rattle sound....which leads to the all too common engine replacement. that means there are metal pieces now in your oil pan and engine. Change the oil, look inside the old oil and pan and see if you have shiny metal pieces.. if so, not good.
Fortunately it did not turn out to be the infamous Elantra NU engine death rattle. I didn't think it was because the rattling sound was totally random and did not match engine rpm speed. In fact, the rattle was loudest and most prevalent during slowest idle and diminished in loudness and occurrence as the engine was revved up.

New alternator fixed the rattle and engine is so quiet now, just the normal sound of injectors clicking and the cam doing its thing.
 

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That doesn't sound like the alternator bearings to me. It sounds more like the decoupler pulley has failed (OAD - Overrunning Alternator Decoupler).
If anyone who doesn't have a warranty is trying to fix that noise you don't need to replace the complete alternator. You can just replace the pulley, which is much less expensive.
 

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That doesn't sound like the alternator bearings to me. It sounds more like the decoupler pulley has failed (OAD - Overrunning Alternator Decoupler).
If anyone who doesn't have a warranty is trying to fix that noise you don't need to replace the complete alternator. You can just replace the pulley, which is much less expensive.
I wish I could have gotten my hands on the old alternator to spin the pulley and see if there were any obvious signs of worn bearings or the decoupler pulley failure. I had asked the service mgr. if I could keep the "failed" alternator but he said I would have to pay the $70 core charge for me to be able to keep it. I decided against that.

I had to educate myself on this decoupler pulley, I was not aware of this mechanical technology on the alternator. I think you are probably right for my noise as it was not speed related and in fact seemed to go away when engine speed was above idle.

Here is a good youtube video to learn about this feature:

 

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I was getting that same noise. Mine was coming from the alternator bearing as well. I replaced the alternator and decoupler pulley at separate times to see which one it was.

If you pull the old decoupler pulley off it has a Litens emblem engraved on the back so this is what I used

$115 but use their 25% off code
https://shop.advanceautoparts.com/p/litens-overrunning-alternator-decoupling-oad-pulley-original-equipment-quality-920015a/10641154-P?searchTerm=alternator+pulleys

The stock alternator is a Denso brand, and if you look up the housing number, that housing is also used in the 2014 Tuscan which runs a 120 amp alternator instead of the Elantra 90 amp, 30 extra amps plus its less expensive. When you get it you'll notice the Kia Hyundai symbols are ground off the casing.

$170
https://www.rockauto.com/en/parts/denso,2116039,alternator+/+generator,2412

Did those about a year and a half ago, 18Kish miles, been running well.
 

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I was getting that same noise. Mine was coming from the alternator bearing as well. I replaced the alternator and decoupler pulley at separate times to see which one it was.
So in your case, which one was the culprit? From your links, it looks like you replaced both items. Did the alternator you bought not come with the decoupler pulley installed?
 

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These new alternators are not what we used to swap on the family GM product, that is for sure! What I find pretty cool is that on my '14 Elantra GT the idle speeds up when you switch the AC fan speed from position 2 to 3 or 4. The voltage drops when the fan speeds up, so the idle is increased about 250RPM to pull the alternator back into regulation. Saves a wee bit of fuel by letting the engine idle slower when the electrical load is less.
 

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My daughter drove her 2012 Elantra Ltd. home from out of state college yesterday. Upon pulling into driveway I hear a noticeable rattling sound from the car. I ask her how long has the car been making that sound? Her response was "what sound" ??..... Car is at 55k miles.
It turned out almost in a similar situation, only the number of miles is slightly less. The problem was solved by replacing the generator. While messing around with all kinds of insurance, I had to rely on https://uk.edubirdie.com/hnd-assignment-help since there was practically no time for the rest. Although before that, I had no idea that I might need hnd assignment help. In any case, I hope that for some time we will forget about the repair of the machine.
 
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