Various mechanical noises long after engine shutdown

[gamedev]

I've noticed two different mechanical noises that occur long after the engine has been turned off, like 45 minutes to an hour after shutdown. The noises only occur occasionally, or maybe I'm only occasionally close enough to the car to hear them.

The first noise is a whirring sound from the underside behind the right rear wheel that goes on for 30 - 60 secs or more. Its a whirr with a sort of "pop" at the end: "whirrrrrrrrrrrr-pop".

The second noise is a rapid clicking from the engine bay that goes on for 20-30 secs. It's sort of like the sound made by those little plastic wind-up toys. Dunno... it's hard to explain.

Lastly, these noises don't happen together. I never hear them both on the same day, and I only hear either of them intermittently. I haven't had a chance to locate the exact source in either case.

Anyone else notice these sounds, or know if they are normal? If they occurred shortly after engine shutdown I wouldn't think twice about them, but 45 minutes later?

Thanks!

 

[FrequentFlyer]

I've never really heard the sounds you're referring to. Especially the rapid clicking. I do hear a fan spin up after shutdown for about 30 seconds and I believe there is a pump that cycles coolant through the turbo after shutdown to cool it off.

 

[Oldcabin]

I've heard the fan and the clicking....but never 45 minutes later.

Of course, I don't often sit in my garage for 45 minutes waiting to hear something

 

[Rotus8]

The noise from the right rear is the gas tank purge pump. I don't know why they cycle it when they do, but it is to check if the tank evap system is working. I guess they do it then because it is unlikely you will be filling the tanks that long after shutting it down and one reason for the check is to see if the gas cap is tight.

 

[dmention7]

I'm pretty sure the clicking is common... as metal parts cool and contract at different rates, you'll often hear clicking/pinging noises especially from exhaust components.

 

[gamedev]

Thanks for the feedback! I figured it was just the car being smarter than I am, but just wanted to make sure there wasn't something squirrely with the electrical. My last vehicle was a 1999 Toyota Tacoma, and when it's off, it's OFF.

dmention7, these are definitely mechanical sounds, not the usual cooldown ticking/pinging.

Rotus8, thanks for the info on the gas tank purge. That explains it. Didn't know about that.

FrequentFlyer, the turbo coolant pump sounds like a likely source. Even after 45 mins some parts are still too hot to touch, so I could imagine a sensor tripping. I'll go with that, to make myself feel better.

Oldcabin: ha, true enough. Sometimes I walk outside and have those "what's it doing now?" moments.

Thanks everyone!

- Chris

 

[oaklandopen]

the radiator fans (especially electric ones) can come on whenever they need to. if you have a black car sitting in direct sunlight in the summer, and you haven't started your car that day, the fan could still come on out of nowhere. and the gas tank will definitley get hot too, meaning the purge canister will have to be opperating to keep the system from over-pressurizing.

if you have a garage the best thing to do (and my dad has done this since god knows when) is prop your hood up as soon as soon as you pull in and park it. this will help expend a lot of the heatsoak that will happen once you shut your car off.

 

[MikeHTally]

dmention7, these are definitely mechanical sounds, not the usual cooldown ticking/pinging.

Rotus8, thanks for the info on the gas tank purge. That explains it. Didn't know about that.

FrequentFlyer, the turbo coolant pump sounds like a likely source. Even after 45 mins some parts are still too hot to touch Man, you got that right! Hard to believe an aluminum motor could stay so hot for so long! I don't think the Hemi in my Ram stays that hot for that long. , so I could imagine a sensor tripping. I'll go with that, to make myself feel better.

I haven't heard mine make noises that long after shutdown, even on these visciously hot Florida summer days. It does click and whir for a few minutes right after shutdown.

Oldcabin: ha, true enough. Sometimes I walk outside and have those "what's it doing now?" moments.

Thanks everyone!

- Chris

if you have a garage the best thing to do (and my dad has done this since god knows when) is prop your hood up as soon as soon as you pull in and park it. this will help expend a lot of the heatsoak that will happen once you shut your car off.

I don't keep mine in the garage, but I open the hood while it's still idling and place two fans on top of the motor, one blowing into the engine bay and one pulling heat out. I shut down the motor and let the fans run 'bout thirty minutes.

 

[sslivingu]

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