85 Monte Carlo with a 2002 goodwrench 305 crate motor with just over 70K. Ever since the last really big cold snap we got up here my car has been making a really loud noise when it is above 20-ish degrees out and the engine is hot. I thought it was my power steering pump since it was having 'morning sickness' issues, but I replaced it and noise is only getting louder. I can really only hear it at idle up to about 1500 RPM, and it sounds like when you jiggle an old loose doorknob around or the chain lift on a roller coaster ride but much louder. Used the screwdriver to the ear trick and it doesn't seem to be coming from inside the engine. I can also feel it through the wheel and the brake pedal and it is so bad that I can also feel it when the car is idling over the normal vibration of the motor. Whenever it gets chilly outside it quiets down again to more of a metal hitting plastic sound and becomes fairly hard to hear from outside the cabin. Every belt driven accessory has been replaced except the alternator which was fairly new when I bought it and the balancer which is one of my prime suspects now. In terms of performance the engine drives just the same as it ever did which just adds to the mystery. Oil has been changed routinely and motor was clean as a whistle inside when I changed my intake gaskets about 3K miles ago.
Mystery Sound
- Thread starter Bludacious
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I was just thinking it MIGHT.....MIGHT be a balancer ring coming loose and moving for some reason. It's not common, but it does happen. Doubtful it would be loose on the crank snout, but you can't rule out anything when it's driving you bonkers and hiding in plain sight.
I was also thinking of another long shot. If you say it's NOT in the engine, it may be possible the torque converter bolts are loose? Flexplate cracked? Just throwing some spaghetti on the wall here.
Is it with RPM (crank related) or slower (cam related)?
I was also thinking of another long shot. If you say it's NOT in the engine, it may be possible the torque converter bolts are loose? Flexplate cracked? Just throwing some spaghetti on the wall here.
Is it with RPM (crank related) or slower (cam related)?
Torque converter bolts were my second thing to check, the shop that did the engine swap for the previous owner did a fairly poor job (failed to tighten 2 of the intake bolts at all, Permatex everywhere to seal the fuel pump, etc) So it could definitely be possible they failed to tighten those. As I said it is the loudest and harshest at idle, as I accelerate it quiets and speeds up and starts to sound like someone ruffling a deck of cards before I stop hearing it entirely. At highway speeds (65+) it does also make random small squeaking noises, like a piece of trim being loose. I should be able to access those by dropping the plastic bell housing shield underneath the transmission, correct?
-shift to D, hold brake and rev engine momentarily to 1200> listen
-shift to R, hold brake and rev engine momentarily to 1200> listen
-report back
-shift to R, hold brake and rev engine momentarily to 1200> listen
-report back
Yes, you can drop the plastic flywheel cover and access the bolts. Also look for cracks in the flexplate and generally any other issues you state.
You know it is very difficult to remotely diagnose a noise that you've never heard, right? These are simply guesses for a place to start. I've also heard exhaust manifold leaks make ticking sounds. Not necessarily clunking sounds, though. If the oil is clean then I can't see this as bearing-related issue. If you had a video or something that would be audible, people here smarter than me could help diagnose.
Without hearing any of it, Helen Keller or Beethoven would have just as good of a chance of knowing where to check!
You know it is very difficult to remotely diagnose a noise that you've never heard, right? These are simply guesses for a place to start. I've also heard exhaust manifold leaks make ticking sounds. Not necessarily clunking sounds, though. If the oil is clean then I can't see this as bearing-related issue. If you had a video or something that would be audible, people here smarter than me could help diagnose.
Without hearing any of it, Helen Keller or Beethoven would have just as good of a chance of knowing where to check!
Watch the flexplate. Mine was making a horrible squeaking knock. Thought the engine was toast. Nope. Bent flexplate. Had a nasty visible wobble to it.
Idk how it happened, but replaced it and it's been fine since.
Idk how it happened, but replaced it and it's been fine since.
Now, I do know this noise isn't an exhaust leak, since mine's had a few from day one I'm already used to those. I can probably get a video later, but for some reason it's only really audible in the cabin, from the engine bay you have to have a very attentive ear to hear it at all..
The balancer would probably not be an issue since it would be neutral balanced it would only throw off the timing marks but not cause an imbalance if it spun unless the elastomer disintegrated and you can physically move the outer ring.
Loose flexplate bolts sound very similar to a bottom end rod knock.
Loose flexplate bolts sound very similar to a bottom end rod knock.
I had a trans mount break and then the engine tilted back slightly causing the fan to hit the shroud but it only took .001 second to figure out what that sound was.
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