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Uh, Oh, here we go.....

Discussion in 'Chevy Trucks' started by White Gardens, Jan 21, 2011.

  1. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665

    Let's start off with a little background on my truck.

    01, C3500 with an 8.1, 4l80e transmission.

    I bought the truck from the local college as they were at the ten year cycle with the truck and they were replacing it. When I bought the truck, I was told that the transmission was replaced a little over a year ago. Basically about 6 months before I got the truck.

    When I drove it home I noticed a funny noise and have been living with it. It makes a whining noise similar to a hydraulic whine of a hydraulic pump or motor. Took it to a tranny shop and they believed that one of the output gears has a chipped tooth, causing the noise. They said it wasn't fatal, but was just going to be annoying. It's just noisy enough that I turn the radio up and not notice it.

    Now, flash forward to the present. Just yesterday I noticed a new noise. In Park/Neutral, I'm getting a slight knocking, consistent noise that is associated with the engine speed. It started yesterday from what I could tell. At first I though it was the motor, but my oil pressure is still reading good at idle (25-30). Listening it sounded like it was coming from the back of the motor, bell housing, or transmission.

    When I put it in any gear, the noise goes away, it kinda winds up (the noise) and disappears. When I shift between forward to reverse, I hear it slightly and then goes away.

    I'm wondering if it's the flexplate or the converter. I'm going to drop the inspection cover today to see if there is any loose bolts on the converter and just to take a look. I don't think I have time to split the tranny and thoroughly check the flexplate though.

    Also, one other thing. My dome light isn't working correctly right now either. It intermittently works with the headlight switch and the two push button lights on it don't work either. Here is the kicker, my dome light flashes quickly when I shift from Reverse to Drive. The only reason I bring it up in this situation is that I'm wondering if I'm getting an electrical gremlin messing with the torque converter.

    That's it guys. If anyone has experienced this problem before, let me know. I'm getting ready to call some mechanics to see if they have experienced these issues or not before I decide to replace anything.

    Thanks in advance,


    NICHOLS LANDSCA PlowSite Veteran
    Messages: 4,362

    You could check all the grounds, good luck
  3. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665

    I'm also going to check my Cat converter too to see if it's rattling. We'll see, I'll keep you guys informed as to what's going on.
  4. MarkEagleUSA

    MarkEagleUSA Senior Member
    Messages: 335

    The 4L80E on my 97 2500 with 153,000 had a similar sound when I brought it home back in August. I added some Sea Foam Trans Tune for about 40 miles, dropped the pan and changed the filter and fluid. The whine went away and the transmission started shifting much smoother immediately.
  5. zzamud

    zzamud Member
    Messages: 49

    Just changed out a flexplate on a 01 k2500 on monday. Customer heard a starter whine. I found the center of the flexplate( 8 bolts) completely ripped out of the flexplate.
  6. thesnowman269

    thesnowman269 Senior Member
    Messages: 965

    the bolts on your torq covertor are loose. take the inspection plate off and torq them down.
  7. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    4l80-e have a big whine shound to them also.

    but ya you got other problems to. like said start basic. check flex plate and convortor bolts.

    if you cant see the flex plate see if a shop close to you has one of those scopes with the cammera/screen . can wiggle that up in easy and see.
    Last edited: Jan 21, 2011
  8. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665

    The whine associated with the tranny is definitively different than the normal whine that these produce. My mechanic originally said the same thing until he got in it and heard it himself.

    Here is a vid of the current noise. It's gotten louder, and I am now noticing it in Drive.

    I did check the converter bolts after taking the cover off and they were all tight. In the vid I revved it a couple of times and you can hear it subside a bit.

  9. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    do us a favor if you will. remove the convortor bolts. slide the convortor back to the tranny. then fire up the motor. easy test to eliminate motor or tranny problem.

    and a cracked but not fully broken flex plate can cause a bad squeaking/scraping sound.

    that dont sound like tranny to me. sounds like motor bottom end possibly. how is the oil pressure ? has it changed any in the last few weeks or so ? what color is the motor oil ?
  10. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665

    Your probably right about sliding back the converter and eliminating the possibilities. I might try a stethoscope first.

    Oil looks good, and oil pressure has been normal for the motor and hasn't changed from what I can tell. That's why I don't think it's the motor, but it's a possibility as I've had that suspicion too.

    My mechanic is off of work tomorrow, so I'll corner him and get it diagnosed. I didn't want to crack into it too far tonight as I couldn't get the inspection cover completely off. I had enough room to turn the motor over and check the bolts, but the exhaust was in the way, so I wasn't able to remove it completely.
  11. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665


    Or at least I think so.

    After taking the truck out tonight to throw a load of salt, it dawned on me.

    I'm almost 100% certain now that it's the harmonic balancer.

    1.) If it was my flexplate, or converter, the noise shouldn't go away, the way it does. Two mechanics told me that if those were the issues, it should be constant.

    2.) If it was my transmission, it should have grenaded by now or at least started acting funny.

    3.) If it was the motor making such a racket, the noise again shouldn't have gone away, and only gotten worse. That and it would have grenaded by now also. It ran extremely well tonight.

    4.) I remembering having a Ford Tempo (Yes I said Tempo:laughing:) in High School that had the harmonic balancer go out on it. It made the same noise in almost the same conditions as this issue is. I also remember it being very loud.

    The noise in the video made me realize that when I shot it, the truck was still extremely cold from the 6* day we had. Tonight when driving I listened a little closer and it sounds like two metal doughnuts rattling together.

    So, Kiss method on this one. I'm going to start with the balancer and go from there. I'll let you guys know if it's it or not.
  12. quigleysiding

    quigleysiding PlowSite.com Addict
    Messages: 1,129

    I had a flexplate that was cracked all the way around the bolts. The cracks looked like a star . The truck sounded just like yours.It didn't make a sound in gear.
  13. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665

    Dangit. Don't rain on my parade. HA!

    I'll still probably check it out, better be safe than sorry.

    What year was your truck quigleysiding ?
    Last edited: Jan 22, 2011
  14. quigleysiding

    quigleysiding PlowSite.com Addict
    Messages: 1,129

    Sorry, it just came to mind after reading this. It was an older 350 that my kid used to beat on.
  15. zzamud

    zzamud Member
    Messages: 49

    Whitegardens let me know if u doing a trans swap im from your area i could lend a hand if ya need it
  16. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665

    Just woke up from getting some sleep after being up all last night watching lots, so I didn't get a chance to look at it again today.

    Before falling asleep my neighbor mechanic called and we talked more about it. He is a ford guy and he talked to all his GM friends and they all say the same thing. Flexplate issues. He even talked about 350's breaking them all the time.

    So we're going to try and take another look at it tomorrow. Even if I got started on it today I wouldn't be able to order parts for it until Monday. Being an 8.1, there isn't a whole lot of aftermarket parts for these motors. I did talk to the tranny shop that I've been talking to and they are going to look into finding me a cheaper one rather than the $444.95 I would be spending for a GM part.

    Thanks for the offer zzamud. Even though me and my neighbor swap services all the time, he recently had twins so his "extra" time is few and far between, so I'll definitively will keep your offer in mind. Even though it's a 2wd truck and a bit easier, it's always nice to have an extra set of hands when dealing with major swaps. Thumbs Up
  17. zzamud

    zzamud Member
    Messages: 49

    I just bought a gm flexplate for an 6.0 for 57.99 so i hope that 449.99 was install price too!! And yes i bought it thru a dealership
  18. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665

    Nope. That is correct. Cheapest I've found right now is $225.00. Like I said, parts aren't as readily available for the 8.1. Heck, even GM quoted me $250.00 for the harmonic balancer.

    Fuel pump for my truck. $398.00 through NAPA, $575.00 through the dealer.

    I'm even crafty when it comes to parts purchases, so the sticker shock of some of these parts are killing me.
  19. zzamud

    zzamud Member
    Messages: 49

    Wow bro. Are u buying the parts under a business or just as a walk in customer?
  20. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588