Whine in engine

Tiny
PLKELLY
  • MEMBER
  • 2004 CHEVROLET TRAILBLAZER
  • 96,630 MILES
I have an engine that sounds electrical. First of all, I am a retired auto mechanics teacher. I have tested everything. PS pump. Alternator replaced. Belt replaced (regular maintenance) New Battery 3 mos ago. Just bought the car to pull my boat. Don't have a history on it. Fan clutch engages and disengages with no change in noise. It really sounds electrical. I unplugged the alternator with no change. Waterpump is tight w/no leaks. Throws no codes. Does not overheat. Runs great (except for not so goos MPG) LOL. I went over it with stethescope and could not detect any noise from the engine itself. Any new ideas. Commom logic seem to defy this one?
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Sunday, September 11th, 2011 AT 8:17 PM

11 Replies

Tiny
PROMECHANIC
  • EXPERT
This is a hard one since I can't hear it. I would try getting a spray bottle with some water in it and spray it on different pulleys and on the belt a little.
Sometimes the belts can cause this type of noise even when they are still good. This should help find a noisy pulley.
You might even try starting it with the belt removed.
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Sunday, September 11th, 2011 AT 9:05 PM
Tiny
PLKELLY
  • MEMBER
Good idea. Already did this. I will keep looking. This one is a mystery. I will post solution when I figure it out. If you have any other suggestions, let me know.
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Sunday, September 11th, 2011 AT 9:14 PM
Tiny
PROMECHANIC
  • EXPERT
So you have tried the water and removing the belt?
What do you mean "it sounds electrical"?
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Sunday, September 11th, 2011 AT 9:15 PM
Tiny
PLKELLY
  • MEMBER
It sounds like an alternator whine when it is under a heavy load or trying to charge a bad battery. It doesn't have that bearing noise like metal on metal. It kinda sings. Sounds like the old whine in your radio in the old days when you didn't use resister plugs or sheilded plug wires. It's downright irritating.
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Sunday, September 11th, 2011 AT 9:20 PM
Tiny
PROMECHANIC
  • EXPERT
Maybe it is a vacuum leak. From your description it sounds like it might be. Maybe try spraying carb cleaner around the vacuum lines and see if the rpm's pick up.
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Sunday, September 11th, 2011 AT 9:32 PM
Tiny
PLKELLY
  • MEMBER
Another good suggestion. It is not a whistle typically assocoiated with a vacuum leak. It would send a service engine message if this were the problem, plus it idles too smoothly for this to be the issue. However, it's worth a double check. I'm leaning towards the water pump, even though it's not the typical bearing noise. I was hoping someone had come across this issue before. It's very hard to diagnose something when you can't hear for yourself. You would know what I mean if you heard it. I've had three of my best mechanic friends listen to it and they all thoght it was the alternator. It had been replaced when I got it. I suspect it was traded in because no one had been able to figure it out. I had a brand new one in my parts bin I put on it and the same issue remained. You are full of good ideas. Are ou sure you weren't in my auto mechanics class?
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Sunday, September 11th, 2011 AT 10:32 PM
Tiny
PROMECHANIC
  • EXPERT
Ha! I'm pretty sure I wasn't, unless you were a professor at Walla Walla University!
I'll try to think of some other things and do some research.
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Monday, September 12th, 2011 AT 12:30 AM
Tiny
CJ MEDEVAC
  • EXPERT
HOW 'BOUT YE OLE SOUTH CAROLINA STETHOSCOPE--4' OF 1/2" HEATER HOSE, ONE END STUCK IN YOUR EAR, OTHER END SEARCHING. WATCH OUT FOR THOSE PESKY MOVING PARTS!

SIMILAR NOISE ON MY BUDDY'S S-10, AFTER A BUNCH OF PARTS THROWING, S.C. STETHOSCOPE, CONFIRMED IT WAS A "KAZOO" RACKET COMING FROM THE THROTTLE BODY. HE CHANGED THE GASKET, ALL WAS GOOD.

GLAD MY OLE JEEPS DON'T HAVE WILD ISSUES, SUCH AS THIS!

THE MEDIC
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Monday, September 12th, 2011 AT 1:00 AM
Tiny
PROMECHANIC
  • EXPERT
It seems like it wouldn't be the water pump if you ran the truck with the belt off?
I was thinking maybe you should check the fan clutch.
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Monday, September 12th, 2011 AT 1:54 AM
Tiny
PLKELLY
  • MEMBER
It makes the noise whether the fan clutch is engaged or not. I will retry some of the ideas. I may try running it with the fan clutch off the pulley. I replaced the belt and checked the idler bearing. Did not run it with belt off. Cleaned all the pulleys and water pump flat side which drives the water pump. Again, thanks for your imput. I am going to bed. I will check it after work tomorrow. I had to take a retirement job. I am teaching GED classes at the state prison. Helps the retirement funds. LOL
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Monday, September 12th, 2011 AT 2:34 AM
Tiny
PROMECHANIC
  • EXPERT
I think I would try running it for a short period of time with the belt off. It would rule out so many things.
I'm sure I'll be working when I'm retired. Just for something to do if nothing else!
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Monday, September 12th, 2011 AT 3:12 AM

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