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Whiny alternator


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#1 BenR.T.

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Posted 18 May 2017 - 04:37 PM

Trying to diagnose a whine in my alternator in my 620 with a 1600 engine. I already replaced the old External regulator with a new solid state one. It is charging right around 14.5volts. Brand new Deka Battery. 

I pulled out the new/rebuilt bosch alternator thinking maybe it had a bad diode, and just put it a brand new one (not rebuilt). I am still getting the same high pitched whine. It increases with the rpms and vice versa.

Is it possibly just bad wiring? 
I am completely stumped, any help would be appreciated!


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#2 datzenmike

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Posted 18 May 2017 - 04:55 PM

Inspect the belt. CAREFULY hold a bar of hard soap against the two faces of the belt that contact the pulleys. Keep away from the fan and watch you shirt sleeves!!!!


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#3 BenR.T.

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Posted 18 May 2017 - 05:09 PM

It's a new belt too.

I am 99.99% sure its not belt noise. I've dealt with that on other vehicles, this sounds different, more like an electric motor running. Kind of a super charger whine.


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#4 kelowg

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Posted 18 May 2017 - 06:11 PM

Belt or belt alignment issue



#5 datzenmike

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Posted 18 May 2017 - 06:15 PM

Well, unplug the alternator. This will eliminate the charging aspect of the noise. (battery, regulator)


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#6 Lockleaf

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Posted 18 May 2017 - 07:10 PM

Is your fan clutch locked up?

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#7 BenR.T.

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Posted 18 May 2017 - 07:59 PM

Is your fan clutch locked up?

 

Fixed fan. No clutch.

 

Well, unplug the alternator. This will eliminate the charging aspect of the noise. (battery, regulator)

 

Ok, unplugged everything, still hear the noise.

 

Took the belt off and the noise is gone. 

 

My thought is possible bearings in the waterpump? It does have a little play when I grab the pump pulley and wiggle it.


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#8 flatcat19

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Posted 19 May 2017 - 09:08 AM

Stethoscope from HF can be had for less than $5.

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#9 420n620

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Posted 19 May 2017 - 09:16 AM

to determining if it's the water pump or alternator making the whiny sound, take a metal rod or 3/8 drive extension/s, long enough so your face isn't getting slapped by the fan or what ever to make a stethoscope to get sound to travel through. Be careful to not get it into any moving parts. With engine running, take the metal rod and carefully put it on the alternator housing and put the other end up next to your ear, touching just before the ear opening, listen to the sound being transferred. Now carefully take the rod and put it close to the water pump housing and listen to the sound. Which one sounds the loudest ?  

 

if it was your water pump, the bushing is on it's way out and you should see some weeping of anti-freeze coming out on the ground.

 

if it's the alternator, sometimes all you need to do is open it up, ( hope you know how to) and put a little grease on the bearings.

 

hope this helps, report back with your findings.   


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#10 Scgreen620

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Posted 20 May 2017 - 10:48 PM

Make sure your alternator bracket is tight I just had a similar problem

#11 spdcrazy

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Posted 21 May 2017 - 05:02 AM

any chance of oil or coolant leaking down to it? if so, clean the alt, and spray some lube on the bearing maybe.

 

but it sounds like you are getting close to a solution!



#12 BenR.T.

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Posted 25 May 2017 - 01:03 PM

Changed the waterpump, which it needed anyway, but it's still making the sound.

 

I am sure it's something with the Alternator. The thing is, this the second replacement I have tried. The first was a Bosch rebuild, this is a brand new one. Both make the same exact sound.

 

What am I missing??


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#13 datzenmike

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Posted 25 May 2017 - 04:21 PM

Bosch is the problem.
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#14 kelowg

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Posted 25 May 2017 - 04:50 PM

Make sure its the right alt and or voltage reg.  Part counter guys tend to screw up,have them look in actual catalogs



#15 BenR.T.

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Posted 25 May 2017 - 05:09 PM

Got the last one from Rock auto. 

Brand new solid state VR as well.

 

Charge is right where it should be.


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#16 datzenmike

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Posted 25 May 2017 - 06:43 PM

Try turning high beams, heater and wipers on see if the wine is louder. Probably will be. The more output the alternator is obliged to produce, the more resistance to being turned by the engine. It's doing work and the bearings will make noise... they shouldn't, but stuff today is cheaply rebuilt with poor quality parts and labor.


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#17 hang_510

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Posted 26 May 2017 - 08:08 AM

Took the belt off and the noise is gone. 

Put a new notch in the belt, or replace it.
I had the same noise and when I replaced the belt, it stopped, esp at high rpm.
Replace cheap,easy parts first. Also be sure all contacts are clean.
I've gone through 3 alternators on this motor, this was the first belt change.

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#18 datzenmike

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Posted 27 May 2017 - 08:02 AM

It may be normal to whine depending on the bearings that were used when re-built.


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