Said It Here

Why does my truck make a rattling noise after I turn it off?

An engine can continue to run, sputter, or rattle briefly after the key is turned off, sometimes sounding like droplets hitting a metal pan. This dieseling or run-on phenomenon happens right after putting the vehicle in park, leaving drivers confused about whether it is a fluid leak or mechanical noise.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

  1. 1
    Checking for carbon buildup, high idle speed, low octane fuel, or wrong timing/rich mix.
  2. 2
    ignoring the sound as normal behavior for an older vehicle
  3. 3
    assuming the noise is just fluid dripping onto a thin aluminum heat shield

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.

r/MechanicAdvice2 people · September 2026

“It only happens when I put it in Park and shut it off. The noise lasts for a little while, then stops.”source ↗

No_Damage21 · r/MechanicAdvice · 3 upvotes

“Engine dieseling (or run-on) happens when a gasoline engine keeps running or sputters for a short time after you turn off the key.”source ↗

Syntax-err_r · r/MechanicAdvice · 1 upvotes
r/AskMechanics1 person · September 2026

“What is this noise my truck makes after I shut it off after driving a while”source ↗

“It almost sounds like droplets of liquid hitting a metal pan.”source ↗

CursedLemon · r/AskMechanics · 1 upvotes

“But what could possibly be dripping like that from under the truck? It's not A/C discharge and I don't have any leaks.”source ↗

CursedLemon · r/AskMechanics · 1 upvotes

Where this came up

People with this problem also raised