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High pitched whine.

Discussion in 'Chevy Trucks' started by 70monte, Jan 7, 2010.

  1. 70monte

    70monte Senior Member
    Messages: 468

    Today when I drove my 98 K3500 with the 7.4L to work, I kept hearing a high pitched whine. The outside temps were 9* but with the wind it was probably colder. The whine would come and go but I seemed to hear it the most around 50-55mph. This happened the entire 30 miles to work.

    After work when I started the truck up to leave, I heard the same noise. I popped the hood and the noise seemed to be coming from the alternator area. The noise finally stopped about half way home. The temps were only about 10*. The alternator is a new 120amp AC-Delco reman. Does this sound like an alternator problem? The inside gauge showed over 14 volts. Has anyone had their alternator make a noise like this. If not the alternator, what else could be making this noise?

    The noise seems to be temperature related since this didn't happen when it was warmer out. Thanks.

    Wayne
     
  2. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    Could be the belt making a little noise from it being so cold. A lil belt dressing should help that
     
  3. 70monte

    70monte Senior Member
    Messages: 468

    I guess it could be the belt. Its the belt that was on the truck when I bought it over two years ago but I've only put about 6,000 miles on the truck since then. The belt looked new when I got the truck and still looks good so I don't know. I guess I will have to keep an eye on it. the temps are supposed to stay cold for awhile.

    Wayne
     
  4. mossman381

    mossman381 2000 Club Member
    Messages: 2,410

    The idler pulley bearing could be going bad.
     
  5. mcwlandscaping

    mcwlandscaping 2000 Club Member
    Messages: 2,557

    Belt dressing is for V-belts only I believe, it is not to be used on serpentine belts!

    Problem noise could be the alternator as my old one on my 97 sounded like that when it went. Idler pulley is easy to take off and check for play that would be show if it is worn, just sucks doing it in the cold!
     
    Last edited: Jan 8, 2010
  6. Rubicon 327

    Rubicon 327 Senior Member
    Messages: 108

    That would be my guess also.
     
  7. 70monte

    70monte Senior Member
    Messages: 468

    That could be it since it looks like the original one. I will check it out and see. Its 8* right now and very windy. Fun time to be working on a vehicle. Thanks.

    Wayne
     
  8. Mr.Markus

    Mr.Markus PlowSite Fanatic
    Messages: 5,163

    Alt could be on the way out, check to see if the front is black with belt dust. I had one whine on the belt in the cold, tested out fine until about a month later, seized. Might want to carry a new one around in case.
     
  9. 70monte

    70monte Senior Member
    Messages: 468

    I think those of you who said idler pulley were right. I took the belt off and checked for play but there really wasn't any but when you turned the pulley, it made some noise and felt pretty rough when you turned it. I bought a new one and installed it and went for a test drive and didn't hear the noise. The real test will be tomorrow when I start it up completely cold and see if I hear anything.

    I don't have any black buildup on the front of the alternator but the alternator is fairly new with only about 1,200 miles on it since I installed it. I guess I will see what happens. Thanks for all the info.

    Wayne
     
  10. 70monte

    70monte Senior Member
    Messages: 468

    Well, I started the truck up this morning and the high pitched whine was still there for about 5 seconds and then was gone and did not come back. The outside temps were about 14*F. I guess I'm going to have to keep an eye out on the alternator. I guess this Delco reman may be bad.

    Wayne
     
  11. Mr.Markus

    Mr.Markus PlowSite Fanatic
    Messages: 5,163

    I bought one from Napa with a lifetime warranty, claims they'll even pay for the tow if it goes bad and replace it. I do wonder how long that'll take but haven't had to use it yet. It will be inevitable though.
     
  12. 70monte

    70monte Senior Member
    Messages: 468

    Well, I started the truck this morning to go to work and it was -6*F out and it didn't make a sound other than some tapping from a lifter until it got some oil to it. No high pitched while so I don't know what to think.

    The truck is taking several revolutions of the engine before it will start so I may be starting to experience the injector or fuel pressure regulator bleed off these engines are famous for. It didn't use to do this. I don't know if the injectors or regulator has ever been changed.

    Wayne
     
  13. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Wayne, mine bleeds off fuel pressure too. I checked it this summer and would be down to just about zero in a half hour. When it's cold, this is how I start my truck. Turn the headlights on for about 10 or 15 seconds. Then the key on, no start, for about 5 seconds. Then I hit start and she lights no problem. Running your headlights for a few seconds warms the battery up a bit.
     
  14. 70monte

    70monte Senior Member
    Messages: 468

    I guess I should start saving for injectors and regulator. Some people on another site are using some ford injectors that are supposed to be better than the stock ones.

    I need to figure out this charging thing that is also going on. Today since it was in the high thirties, my volt gauge is reading below the 14 mark. I don't know if its the alternator or some wiring issue. It seems like the alternator doesn't like any heat at all.

    Wayne
     
  15. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Wayne, those dash gauges do not have very good resolution. You can get a digital voltage monitor at Wally World, AZ, etc. that pops right in the cigarette lighter. Or you could rig up a cig lighter plug to connect to your VOM.

    But I too have noticed my voltage drops as things warm up. Go out at 2am when it's 10* out and the gauge will be three ticks above 14. Within an hour it will be just above 14.
     
  16. 70monte

    70monte Senior Member
    Messages: 468

    I finally tested my voltage today and it was running 14.23 volts while the gauge was sitting on one mark before the 14 so I guess my gauge is not accurate. Now I will have to see how long this battery lasts.

    Wayne