loud engine rattle. loose flywheel?

Discussion in 'Chevy C/K Truck Forum' started by fishon91, Sep 17, 2013.

  1. fishon91

    fishon91 New Member

    Ive had a bad rattle coming from the area of the bell housing. I put some lucas transmission additive in the other day hoping it would quiet the noise if it is a torque converter shudder or vibration, no change yet. I don't recognize this noise so Ive been trying to find videos with similiar noises. The only ones I have found sound similair are like this, where they say they have a loose flywheel. The noise I am hearing sounds like a loud, rattling or grinding noise, but its a deep sound like thicker metal rattling together, not like thin heat shields rattling. Its not a rhythmic knocking or tapping. It happens very quietly at idle, loudly when first accelerating right after decellerating (like when you first press the pedal after a turn). It gets really loud when going up a hill and just steadily going, above idle, up the hill. I have to press the gas and acellerate more to get the noise to stop.

    I am positive that I have driveline issues. The whole truck vibrates after 40 mph. When I bought this truck it had a dented rear driveshaft and a bad center bearing. I replaced just the rubber on the center bearing since I don't have a press and the bearing had no play. I got a rear driveshaft from another truck that, and as far as I can tell is in good condition but the vibration has not gone away. I put the driveshaft in the same way it came out with new u-joints. I plan to take it to get balanced as one piece. I am almost positive it is a driveshaft vibration because after I take the driveshaft off and put it back on, the vibration goes away for a bit, but comes back.

    Is there a way to test and eliminate the possibilty of loose flywheel bolts? I'm not sure if I will have access to tools to drop the transmission to change a flywheel. Im in college and my parents just moved out of state and sold the home that housed all my tools. So I dont have anything with me and refuse to pay someone to do this work until it involves internal motor or transmission.
    If needed, I will try to post a video today of the noise.

    Thank you all very much for your input.
  2. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    you might be able to drop the inspection plate and look up there with a flash light.
  3. fishon91

    fishon91 New Member

    I just got done doing that, removed both inspection plates, the bigger one by the motor and the smaller on behind the Torque Converter. Everything looks fine as far as I can see. no play in the flywheel or TC. I started the motor and lookes for warpage in the flywheel, it looked fine. Up close, it sounds more like it is coming from the transmission, but what could be making noise in the transmission while the truck is in park? I have an automatic, 4L60E, I think.

    More info on the truck: 1998 c1500., 4.3 L, 2wd, 140,000 miles.
    Has had a small wreck to the front right side, no chassis or steering damage, only body damage.
    I believe the truck was in a salvage yard and possibly picked up with a forklift causing the dent in the driveshaft. This all happened before I owned it. Previous owner obviously took very good care of it as it is in pristine, OE condition for everything else.
  4. Caddiac

    Caddiac Epic Member 5+ Years 1000 Posts

    If I understand you correctly you have a noise and vibration problem. Your truck has a two piece drive shaft which had a dent in the rearward section of the shaft. You replaced the rubber in the center support bearing and the damaged section of shaft. You still have some vibration and but the noise has not changed. It sounds like you are more concerned about the noise because, it sounds like to me, you are aware that the shafts have to be balanced as a set. Is that correct?

    I have the factory manuals for the 98 and will re-read your previous post to try and point you in the right direction. Let me know if I am on the right track and I will follow up with things to check.
  5. fishon91

    fishon91 New Member

    That is correct. The noise and vibration should be two separate issues because the vibration has been there since I bought the truck. (I bought bought it under the assumption of a bad center bearing).
    The rattling noise has only shown up in the past couple of weeks. Ive had the truck almost 6 months. I am going to NAPA to get the driveshaft balanced, together as a set, and replace the u-joints, hopefully this week.

    Could an out of balance driveshaft have caused a bearing to go out? Possibly a thrust bearing on the output shaft that only makes noise when the load, or thrust, changes acceleration? If I took out the rear transmission seal and pushed/pulled on the front-most joint of the front driveshaft could I check for endplay in that bearing? I know very little about Automatic transmissions, but I imagine there has to be a thrust bearing there.
  6. Caddiac

    Caddiac Epic Member 5+ Years 1000 Posts

    Vibration in rotating machinery is never a good as over time it only does more damage. That being said, it depends on the source of the vibration among other factors as to whether or not it caused additional damage.

    When you replaced the rear shaft you said you changed the universal joints. What about the others? If not, check these joints for play and also make sure there is nothing rubbing around the center bearing or at either end.

    Don't be insulted but are the tires are in good shape, no road noise, tire balance issues, steers okay?
  7. fishon91

    fishon91 New Member

    tires are not in the greatest of shape. Well... Theyre in okay shape but they are cheap tires and do make some occasional road noise. It may not be a bad idea to make sure those are balanced. I rotated tires about a month ago, fronts straight back and rears straight forward. It immediately pulled to the right so I swapped the front tires and it straightened out.
    History on the tires: When I bought the truck it had good quality tires on it (Hankook maybe) that were getting wore down. (Still had the driveline vibration though). So I had the good tires on my old ford swapped with the wore out tires on my new chevy so I didnt have to pay for new tires and they were the same size. Rebalanced and new valves was all I had done. Didnt affect the driveline vibration at 40+ mph.

    Ive checked for play in the u-joints and have not had any. I'm only checking by putting in neutral, chocking the tires, grabbing the drive shaft and trying to turn it. No play in the u-joints. All u-joints were replaced when I changed the rear shaft.

    Thanks again for your interest in my situation. You're not gonna offend me with any questions. Heck, I haven't even thought about checking the tires for balance until you mentioned tires. I don't think that is the issue, but I can get that done cheap.
  8. zippstripp

    zippstripp Member 1 Year

    Been reading the posts. My question is where do you notice the vibration? is it in the seat/cab area or in the steering wheel? A couple thoughts about the clunking heavy noise in the bell housing area. Flywheel may not be loose but cracked especially between the bolt holes to the crank. Or torque convertor nose that engages the pump maybe cracked or broke. Just a couple of ideas, I have seen both.
  9. Grady

    Grady Member

    I was thinking the same - flywheel cracked between the bolt holes. Not as expensive as tranny but just as much fun.
  10. TimTom64b

    TimTom64b Epic Member 5+ Years 500 Posts ROTM Winner

    Do you know if the engine and tranny were ever separated... I hope its not but it sounds like something I experienced many years ago when I did my first tranny install... I did not engage the splines on the torque converter and the transmission. Luckily I caught it in time when I first started the engine.

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