Mechanically, what keeps spinning after engine shut off?
11-09-2018, 05:40 PM
#1
Melting Slicks
Thread Starter
Mechanically, what keeps spinning after engine shut off?
i have what I can best describe as a “cricket noise” on cold starts. As the car warms, it lessens. If I raise the rpm it comes back. Chirp chirp noise. Speeds up as rpms increase. Goes away at idle. Completely goes away when car is hot. however, when I turn the car off the squeak is clear for a while and then slows and eventually stops. What parts keep “spinning” after engine shut off? Shop is telling me it’s the “pulley” on the ac compressor which needs to be replaced. Do pulleys keep spinning after engine shut off? I just recently replaced the serpentine belt. Thanks.
Last edited by STRMLNE; 11-09-2018 at 05:41 PM.
11-10-2018, 08:20 AM
#2
Le Mans Master
Pro Mechanic
Nothing keeps spinning after the engine shuts off generally speaking. There MAY be certain circumstances where the electric fans keep spinning...not sure on that one.
11-10-2018, 03:28 PM
#4
Le Mans Master
If its the same noise after shutting off the motor, then it's not connected with the motor. All belts, pulleys, etc. stop moving.
Perhaps the fans may carry on as noted above? Is it warm where you are? Can you post a video? You need to pop the hood and watch.
I have a feeling that shop is using your money to find the issue with trial and error.
Perhaps the fans may carry on as noted above? Is it warm where you are? Can you post a video? You need to pop the hood and watch.
I have a feeling that shop is using your money to find the issue with trial and error.
11-10-2018, 04:33 PM
#5
Melting Slicks
Thread Starter
Thanks. Do the fans rate of speed increase when the RPM increase? When the car is cold I can give it a little gas and the cricket noise increases in frequency. (It sure sounds like the same chirp when the car is turned off.)
11-10-2018, 05:46 PM
#6
Drifting
The fans rate of speed is determined by engine temp. There’s two settings, low and high. Engine revolutions are not in themselves controlling the fan speed.
My guess also would be you have a pulley or something going bad.
Another thing if you have a manual transmission car make sure you are pressing the clutch down, holding it down, and then turning off the car to alleviate forces on the clutch fork.
My guess also would be you have a pulley or something going bad.
Another thing if you have a manual transmission car make sure you are pressing the clutch down, holding it down, and then turning off the car to alleviate forces on the clutch fork.
Last edited by Velocity_Vette; 11-10-2018 at 05:46 PM.
11-10-2018, 07:31 PM
#9
Instructor
**** down? My car doesn't do that.....
11-10-2018, 09:17 PM
#11
Melting Slicks
i have what I can best describe as a “cricket noise” on cold starts. As the car warms, it lessens. If I raise the rpm it comes back. Chirp chirp noise. Speeds up as rpms increase. Goes away at idle. Completely goes away when car is hot. however, when I turn the car off the squeak is clear for a while and then slows and eventually stops. What parts keep “spinning” after engine shut off? Shop is telling me it’s the “pulley” on the ac compressor which needs to be replaced. Do pulleys keep spinning after engine shut off? I just recently replaced the serpentine belt. Thanks.
However, you fail to mention for how long the noise persist after you shut down the engine.
0.5 seconds? or 5 seconds? or 15 seconds?
This is the critical clue
11-10-2018, 10:15 PM
#12
Drifting
Auto cars have an alternator decoupler pulley that makes noise for a few seconds after shutting off the engine when it is going bad.
Here is a link to when I did mine.
https://www.corvetteforum.com/forums...placement.html
Here is a link to when I did mine.
https://www.corvetteforum.com/forums...placement.html
Last edited by Ed Ramberger; 11-10-2018 at 10:21 PM.
11-10-2018, 11:59 PM
#13
Le Mans Master
11-11-2018, 09:51 AM
#14
Team Owner
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St. Jude Donor '05
Chirp on startup...I bet your idler pulley/bearing is going bad. Cheap fix
If its a slight chirp when you shut it off cant say its a problem, my 5.3 has done that almost every time since new
If its a slight chirp when you shut it off cant say its a problem, my 5.3 has done that almost every time since new
11-11-2018, 03:02 PM
#16
Melting Slicks
Thread Starter
Thanks for the responses. Looks like I have two squeaks.
One is on cold starts and is a cricket noise that lasts until car is warmed up. Shop replaced serp belt and checked all pulleys. Says that’s not the problem. Says that it’s the pulley on th ac compressor squeeking. They are taking the ac belt off and re checking and will let me know.
Other squeek after shutoff is definitely a cooling fan blade. I can spin the passenger side blade when the car is off and is squeaks like crazy. Can these blades be lubricated? Or does the whole assembly need to be replaced?
Thanks for the help.
One is on cold starts and is a cricket noise that lasts until car is warmed up. Shop replaced serp belt and checked all pulleys. Says that’s not the problem. Says that it’s the pulley on th ac compressor squeeking. They are taking the ac belt off and re checking and will let me know.
Other squeek after shutoff is definitely a cooling fan blade. I can spin the passenger side blade when the car is off and is squeaks like crazy. Can these blades be lubricated? Or does the whole assembly need to be replaced?
Thanks for the help.
11-11-2018, 09:27 PM
#17
Burning Brakes
Fan motors can be replaced OR you can buy the whole assembly.. Not much diff in price to do either way.
The fans would not "always" be on , unless you are shutting down engine with AC on or in a very hot climate.
The fans just don't run that often.
Make sure you keep clutch pressed in while shutting the engine off on any Manual C5
The fans would not "always" be on , unless you are shutting down engine with AC on or in a very hot climate.
The fans just don't run that often.
Make sure you keep clutch pressed in while shutting the engine off on any Manual C5