Name this sound

[Dug Nichols]

Hive mind of gurus, this winter I did a bunch of work on my '73 and finally have it in driving condition -- short trips around town to further suss out issues. (over the winter re-did the entire suspension, front end steering components, fixed oil leaks, etc). I've got what best can be described as a rattling sound:

• occurs while driving the vehicle, but not when revving motor standing over it
• occurs in any gear, between 3k - 4k RPM's, but only when not accelerating hard and in cruise/sustain mode
• sounds to me like a loose metal component in the motor/trans area that just vibrates at a certain resonant frequency. maybe?

 

I'm attaching a video -- note that on take off I'm next to a truck so you hear it shift gear, and then during the vid I'm hitting manholes and bumps in the road (spring in the midwest joy!  ) so those noises, you'll hear it as I back off the accelerator when I'm in 2nd gear and hover around 3700 rpm

 

Curious if anyone has experienced a similar issue -- super hard to self diagnose.

[gracer]

I couldn't hear anything abnormal.  G

[JerryC]

I could hear the noise you described. It sounds familiar for some reason, but nothing clicked in my tiring brain. It sounds like a loose part that likes to rattle at that engine speed.

 

Is there a loose part on the exhaust pipe, or a loose baffle inside one of the mufflers? Try banging on the exhaust with a rubber mallet, maybe it will reveal itself. Also, check the shift linkage for loose parts (that might be what's nagging at me). Finally, I recall having a loose alternator pulley at one time that made a rattly sound sort of like that one.

 

Doesn't sound like it's inside the engine to me, but I wasn't in the car to hear it for real so... take all this with a grain of salt. That's my .02 cents worth, anyway.

Jerry

[aldo.navarro]

I second gracer.

Although there are lots of sounds I hear my 02 make that end up being normal, at least according to my mechanic.

 

[JerryC]

Yep, I still hear it. Cazcajo and gracer made me wonder if I had lost all the marbles, but I think there is a rattly sound in the background of your video soundtrack.

 

How are the engine mounts? Maybe something's rubbing when the engine moves. It's usually something to do with the exhaust when that happens, but shift linkage can sometimes rub on something too.

[visionaut]

Not sure what I’m hearing - but rattles due to on/off throttle or holding it at a specific RPM range, coming from under the car, might be: loose heat shield, loose resonator baffle, exhaust /driveline contact, worn tranny mounts…?

[tech71]

Wish my car sounded that good

 

[LindrelT]

I hear it…. Very metallic like a piece of metal dragging on the road lightly.  But I’d guess more likely it is from something touching a rotating part like engine pulley, drive shaft section or half shafts.  That stuff all may shift a bit with engine under load vs. not.  Get under and look at all those items for evidence of touching - fresh scoring or shiny circles on rotating  parts.  Good luck!!

Edited April 20, 2022 by LindrelT

[EricA]

Exhaust manifold heat shield loose?

[esty]

soundtrack from Gone in 60 Seconds

 

[Mike G]

Didn’t you just rework your exhaust a couple days ago? I’d get under there and see what it’s hitting. 

[FunElan]

Remove heat shield, report back. 

 

Your car sounds awesome. My car sounds like a lawnmower compared. 

[Dug Nichols]

Good ideas all here! TY

 

I re-did the exhaust on my Mintgrun, this is my other 02, a ‘73 original owner car (before me) I found a few years ago locally, had been sitting for a long time and has been a long but enjoyable process sorting through while I’ve got my Mintgrun for real drives.

 

I put an IE Stainless on this car and it’s solid (and a nice exhaust note). I really really like the thought of heat shield! I know it’s hard to hear in the video, but this is definitely not a normal sound and has that metal rattle (and thin metal possibly) sound that sure seems could be a loose heat shield. Gonna check that (after it stops dumping rain) and report back. 

[jp5Touring]

Thought heat shield or something rotating also.

The same contractor must build Michigan roads also.  

[adawil2002]

Going with loose heat shield for $200

 

The IE stainless has loosened & is hitting something. They are notorious for working their way loose.

 

Walloth Nesch sells a great stainless exhaust that is the same design as the stock non-stainless. Have it on my 1600, it's very nice even at 5500 rpm.  

Edited April 20, 2022 by adawil2002