Rattling at idle

[XenoKing]

I just bought my 86 and found after starting the car when it idles out there is a loud rattling noise in the cabin coming from under the car. It's only when idling. Any idea's?

[RZNT4R]

Depress the clutch to see it if goes away.

These transmissions can be noisy at idle as the backlash in the gears goes clack clack. It's audible with the GF-3 molasses the car comes with and it's even more so if the gearbox oil has been changed for higher quality synthetic fluid, I'm running amsoil mtg 75w90 and yeah, clackitty clack clack :lol

[XenoKing]

I tried it but nothing changed, its coming from under the backseat console area. once i take off its gone but comes back when i park.

[humfrz]

Originally Posted by XenoKing

I tried it but nothing changed, its coming from under the backseat console area. once i take off its gone but comes back when i park.

Welcome, XenoKing, to ....... The Forum -

I suggest you put your car up on a lift and see if you can figure what is lose under there. Maybe a panel, maybe a part of the exhaust is banging on something?

Maybe something under the mat in the trunk?

[Ultramaroon]

If you can capture the sound, post a clip on ewe toob and link here.

[Grady]

Any modifications? Lightweight flywheels cause more noise.

[XenoKing]

Here is my video of the cars drone/rattle


https://youtube.com/shorts/AQyMwFodvZg?feature=share

[Ultramaroon]

Sounds like exhaust ... something. Could be an internal part of the muffler rattling. Doesn't sound like a leak but I wouldn't rule out anything. I'd back it up onto a pair of ramps and listen from underneath.

[soundman98]

check your heat shields under the car. first thing that likes to corrode and drop usually..

[RZNT4R]

I don't know if I'm hearing the same thing you're hearing but...

... Lower the rear backrest, see if you hear it more.

The dull slapping that seems to match the exhaust pulses may be coming from the rear body vents hidden behind the rear bumper in the corners of the trunk. At idle, exhaust resonnance can make the flaps oscillate in time with the pulses. I know my stock 86 with stock exhaust does it when I park it home backed to a brick wall. Your car with the obviously loud exhaust may be more severe.

[Ultramaroon]

If that's the case, closing the windows and running the blower would at least change the sound if not eliminate it. Interesting.

[B-R-Z]

There's a clamp that holds the exhaust to the car that has come loose on me a few times and makes a rattle noise. I've hit it going over speed bumps a few times and that makes it come loose.