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Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 12785
Experience:  Have owned a repair shop for 25 yrs.
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new alternator installed have a whining noise sounds to me

Customer Question

new alternator installed have a whining noise sounds to me like there is a draw already on the alternator, there are three wires going to alternator one red going to back of alternator and a red and brown going to side of alternator in a black connector if i unplug this black connector amp draw/whining goes away, what could be causing this whining sound? it basically sounds as if there is a draw on the alternator already..
Submitted: 3 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 3 years ago.
Chat Conversation Started
tims auto repair :

hi

tims auto repair :

is the battery good?

Customer :

yes tested good

tims auto repair :

ok

tims auto repair :

are you getting the alternators in the same place?

Customer :

yes

Customer :

they are brand new units not rebuilds

Customer :

replaced alternator 3 times

Customer :

see i am a auto machanic in engine repairs not electrical

Customer :

so feels funny asking questions but this has me puzzled

tims auto repair :

ok..you need to load test the battery with the car not running...then load test the charging system with the engine running

Customer :

did a load test on battery with a hand held load tester and checks out good

tims auto repair :

does s the battery run down after it sits?

Customer :

no

tims auto repair :

ok

Customer :

battery holds about a 12.62 charge

tims auto repair :

under load?

Customer :

no just sitting not started

tims auto repair :

i mean when you put a load on the battery with the load tester ..most testers will put a 100amp load on the battery

Customer :

if i use the load tester that goes right to battery terminals it pulls down to about 11.2 -11.4 and it is a 50amp load tester

tims auto repair :

ok

tims auto repair :

does it start well?

Customer :

yes strong starter sounds healty

Customer :

powerful start

tims auto repair :

ok

Customer :

see it is not like a bad bearing sound it is a whining electrical sound

tims auto repair :

how about when you load it for 2 seconds with it running?

Customer :

honestly did not try that

tims auto repair :

can you try that..

Customer :

the alternator sounds as if ac, rear defroster , wipers headlights and all accesories are on

Customer :

i can if u give me about 3 minutes i can try that

Customer :

and let you know

tims auto repair :

ok

Customer :

be right back

tims auto repair :

dont hold a load too long

tims auto repair :

k

Customer :

ok here is the results

tims auto repair :

k

Customer :

13.8 in drive and i even did in gear and that is 12.6

Customer :

no accesories on either

Customer :

except hood light

Customer :

ok

tims auto repair :

it seems to be operating correctly

tims auto repair :

how many volts running with no load?

Customer :

yes it seems to be doing everything right except the whining sound is horriable

tims auto repair :

how many voltswith no load?

tims auto repair :

running

Customer :

around 14.4 14.6

Customer :

maybe even 14.8

tims auto repair :

ok

tims auto repair :

when you unplug the regulator plug...the whine completly stops?

Customer :

yes

tims auto repair :

ok...i think this may be a bad batch of alternators....sounds as if the front bearings are bad

tims auto repair :

there would be no reason for this

Customer :

the brown wire from regulator goes to fan fuse relay and the red goes down around to starter

tims auto repair :

even under a load

Customer :

it is no bad bearing

tims auto repair :

the red,,is supose to go to the switch

Customer :

i did a test with a ear probe and there is no noise barly with the regulator wire unplugged just only while plugged in like it is under a load

tims auto repair :

the brown to the charge light

Customer :

i dont have a light a guage

Customer :

camaro rs 305 engine tbi

Customer :

red goes to what switch

Customer :

according to wiring diagrahm goes to starter

Customer :

here is the diagram

tims auto repair :

let me switch to a different format..i will send you a diagram

Customer :

i have a diagram

tims auto repair :

..the bearing has no pressure on it when it is unplugged and not charging

Customer :

so how can it be a bearing

tims auto repair :

well..under load..the elctromagnets pulls on the ohmeter..putting pressure on the bearing

Customer :

it is an electrical whin not a bearing noise

tims auto repair :

after you start the car..even if nothing is on..the alternator will be under a load until the battery is fully charged from starting

Customer :

yes but the noise is there always even after driving vehicle for 2 hours

Customer :

see it never did this before just started recently and i only heard the noise if say defroster headlights and rear defroster and wipers are on

tims auto repair :

Charging System Wiring Circuit (VIN E)


[IMAGE][SRC][/SRC][ALT][/ALT][WIDTH]138.60294117647058[/WIDTH][HEIGHT]100[/HEIGHT][STYLE][/STYLE][/IMAGE]

tims auto repair :

ok

Customer :

but now i hear it with everything off

tims auto repair :

lets try an alternator from a different place

Customer :

well i recently paid 120.00 for this one and they are brand new not rebuilt ones

Customer :

and all three from three differnt stores

Customer :

but same store name

tims auto repair :

i think its a bearing

tims auto repair :

but

Expert:  Tim's Auto Repair replied 3 years ago.

Charging System Wiring Circuit (VIN E)

tims auto repair :

if you want i will opt out

tims auto repair :

the alternator is working right

Customer :

yes but i really am just trying to find out what is causing the problem you know

Customer :

lets say i use a working alternator from another same car that does not have the noise but i install it on this car and it does , then what can it be

Customer :

ok

Expert:  Tim's Auto Repair replied 3 years ago.

then....me and you both will be lost..lol

Please ACCEPT my answer so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my answer.it does not cost you more money.we will still be able to communicate.. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.PLEASE ASK IF YOU NEED MORE HELP

Customer: replied 3 years ago.
Relist: Incomplete answer.
Customer: replied 3 years ago.
Relist: Incomplete answer.

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