Any chance you have a loose, rusting apart or bent dust shield on your brakes?


Also - not sure if you have disc brakes all the way around, but I created a noise similar to this once when I replaced the brake pads and failed to get one of the shims in the proper place... Bent the heck out of the shim and a corner of the pad was rubbing. Sounded awful.

There should be a "dust cover" between the motor and the front of the trans that can be removed to inspect the flywheel/flex plate, whatever you want to call it. Look for shiny spots and metal shavings on the flex plate gear teeth ends and on the end of the starter drive gear teeth if you think it may be the starter. Also check for metal shavings in the dust cover when you remove it. The flex plate that the torque converter bolts to have been know to crack also.

Sounds like the torque converter.

Could be anywhere .etal joins metal. Between the head and the header, header and crossoverpipies cover pipies to muffler....

U joint? I have had them go bad and only squeak while accelerating.

quote:

Originally posted by Mikito:
U joint? I have had them go bad and only squeak while accelerating.

Oh yeah, My truck did this too.

I concur on the U joint.

Fan hitting the shroud? Try "brake-torqueing" the engine. At a standstill with your foot firmly on the brake and the parking brake set, put the transmission in drive, press the accelerator and see if it makes the noise. If an engine mount is broken the engine will jump up and the fan will hit. If you just do it in park or neutral there is no force other than the engine's own weight exerted on the mounts. Or look for signs of the fan blade tips or inside edge of the shroud getting scratched up.

quote:

To look for vac leaks can I spray carb cleaner or wd40 around the engine bay and listen for changes in rpm?

What was the electrical problem a few years back? This car has been causing me issues for 15 years now. Lol. They tend to blend together.

Re looking for leak...You'd be better off with a slightly on but unlit propane torch, I think.

Electrical problem? Whoo, it's been a few years but, IIRC, I believe it was a battery charging problem? The cause? Bad ground between engine block and frame?

quote:

Originally posted by egregore:
Fan hitting the shroud? Try "brake-torqueing" the engine. At a standstill with your foot firmly on the brake and the parking brake set, put the transmission in drive, press the accelerator and see if it makes the noise. If an engine mount is broken the engine will jump up and the fan will hit. If you just do it in park or neutral there is no force other than the engine's own weight exerted on the mounts. Or look for signs of the fan blade tips or inside edge of the shroud getting scratched up.

No noise here. In the video I do this, I think 3 revs. Then I shift into park and 2 more revs.

I put the rear end up in the air and started her up. Then I shifted in gear, with brakes applied, and gave some gas. No noise, as expected.

Then I took my foot off the brakes and gave it more gas so the wheels were spinning. Obvious torque as the whole car kinda twisted on the jack. No noise at all. I expected noise at this stage... it’s not conclusive I know, as it doesn’t do it 100% of the time, but I thought I’d hear it. For what it’s worth I jacked it up from the rear end housing so the downward pressure on the suspension should be the same as if it was sitting on the ground.

If it is a ujoint is there an outward visual cue that it’s bad?

Also check the differential. Check the fluid, listen to it with the car jacked up, or with the rear seat out while driving. The play between the gears could be increasing, and the differential is "hunting".

Usually U-joint start making noise when going around a corner. However a visual inspection with the driveshaft disconnected is very reliable. Easy to do, just four nuts. However sometimes you need a quality wrench, such as Snap-On, to remove the nuts.

Check for a cracked or broken flex plate aka flywheel. Also check for excessive thrust bearing aka main bearings in the engine. You can check that by a pry bar between the engine block and the flex plate and the between the torque converter and the transmission case and try to move the assembly forward and backwards.

While doing the forward and backward movement like I described if possible have someone watch the harmonic balancer at the front of the engine. If you have perceptible movement in the rear of the engine but none in the front you could have a broken crankshaft. Most unlikely from the noise I listened to but still you need to rule it out. And yes, a small block Chevy CAN run with a broken crankshaft. Usually there is a jagged enough break that the crankshaft will "kind of hold" but will move side to side on a rotational basis.

I don't think it is a transmission based noise, I'm putting my money on a bad flexplate. That 15 +/- y/o 350 should have a one piece rear main seal or as some call it a neutral or externally balanced crankshaft. The only 350's that still have the old school two piece rear main seal are the 350/290 hp GM Performance engine and the 350 Universal engine that some people call a 260 hp. GM never gave that engine that hp rating, somewhere here in one of my old GM Performance Parts books (I used to do that for a living) I have a GM Performance case number on that very matter.

Only other thing I can think of, is the flywheel cover metal or plastic? If metal, has it been dented and if there is crankshaft thrust movement is it dented in enough to contact the flywheel when the engine is loaded?

I wish I was closer, I'd give it a look.

quote:

Originally posted by c1steve:
Also check the differential. Check the fluid, listen to it with the car jacked up, or with the rear seat out while driving. The play between the gears could be increasing, and the differential is "hunting".

Usually U-joint start making noise when going around a corner. However a visual inspection with the driveshaft disconnected is very reliable. Easy to do, just four nuts. However sometimes you need a quality wrench, such as Snap-On, to remove the nuts.

Never dropped a driveshaft before... 4 nuts where? 2 on each side of shaft?

quote:

If it is a ujoint is there an outward visual cue that it’s bad?

Rust around the cups is one clue, end play another, but it would be better to take the drive shaft out. Typically four bolts holding two U-shaped straps against the differential yoke, or possibly U-bolts. Pull the shaft out of the transmission, with a pan underneath to catch any possible fluid, then flex both U-joints in all four directions. To make that much racket, one would have to be completely seized up. If it is, it will be very apparent.

quote:

Originally posted by thumperfbc:

quote:

Originally posted by c1steve:
Also check the differential. Check the fluid, listen to it with the car jacked up, or with the rear seat out while driving. The play between the gears could be increasing, and the differential is "hunting".

Usually U-joint start making noise when going around a corner. However a visual inspection with the driveshaft disconnected is very reliable. Easy to do, just four nuts. However sometimes you need a quality wrench, such as Snap-On, to remove the nuts.

Never dropped a driveshaft before... 4 nuts where? 2 on each side of shaft?

As the very end on the differential yolk itself.
You can't miss them. Probably 3/8" or 7/16.
2 on each side.

Watch the engine torque over as you power-brake in forward and reverse. You probably need motor mounts. Excess engine movement can open exhaust leaks and cause other problems (even a fan hitting the shroud).

quote:

Originally posted by Some Shot:
Watch the engine torque over as you power-brake in forward and reverse. You probably need motor mounts. Excess engine movement can open exhaust leaks and cause other problems (even a fan hitting the shroud).

This made me think... when I shift from park to drive it reverse the car “jolts” a pretty significant amount. I think more than it used to. Is that a potential sign of mount wear?

Maybe, or U-joint.

The noise has disappeared... I took it out for a spin and was driving with my head out the window trying to really listen. I’m nearly positive it was coming from the rear tire area. Is it possible a rock or something got wedged agaibst something in the wheel/drum area and then happened to fall clear?

Sure.

Or maybe the part that was loose, fell off.