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A humming noise from the engine

S

Samzeroh

Passed Driver's Ed
Location
Los Angeles CA
Hello everyone. In efforts to keep my car as healthy as possible, I always give it a min or so of idling before shutting off the engine. Sometimes I stay on my phone until that time is over, and pretty often I get hooked on some article and I stay in the car after I shut it off. Here's the deal I've always noticed a humming noise coming from the engine. Yesterday it lasted about 4 min or so. Could it be the fans? What would it be? Hopefully nothing I should be worried about.
 
L

LeGti

Ready to race!
Location
France
Electric water pump seems like a primed candidate.

Yeah, sorry a** pun intended.

;-)
 
T

TheSwede

Ready to race!
Location
Sweden, Halmstad
Car(s)
Golf7 Alltrack/Cupra
Electric oil circ. pump (low pressure). Cooling parts as turbo and so on.

Level on dipstick will increase when shut of.

/Peter
 
S

Samzeroh

Passed Driver's Ed
Location
Los Angeles CA
kboger13 said:
I have the same thing but it's done that since day 1 so I haven't worried about it
Click to expand...

I've noticed it since the first day, but was too excited to be bothered lol it was extra clear to me last night since I was there long enough until it completely turned off. That's when I started to think about it.
 
F

Fluxion

New member
Location
Maine
After a run the turbo can get hot. If you just shut off the engine, the remnant heat can cause the oil in the bearings to overheat and essentially burn, turning into a hard deposit (called coke) which is not very good at providing lubrication. As a result, the bearing can fail (bye, bye turbo). To prevent this scenario, the oil pump continues to circulate the oil through the turbo bearings until the temperature has dropped to a safe level at which point it will turn itself off (there's a thermostat) and everything is cool (literally). Years ago, I remember that Saabs, which were one of the early cars to use turbos, told the owners to allow the engine to idle for a while after a run to allow the turbo to cool down. VW has automated the process to idiot-proof it. I would worry if I did not hear the humming when I turned off the engine.
 
S

Samzeroh

Passed Driver's Ed
Location
Los Angeles CA
Fluxion said:
After a run the turbo can get hot. If you just shut off the engine, the remnant heat can cause the oil in the bearings to overheat and essentially burn, turning into a hard deposit (called coke) which is not very good at providing lubrication. As a result, the bearing can fail (bye, bye turbo). To prevent this scenario, the oil pump continues to circulate the oil through the turbo bearings until the temperature has dropped to a safe level at which point it will turn itself off (there's a thermostat) and everything is cool (literally). Years ago, I remember that Saabs, which were one of the early cars to use turbos, told the owners to allow the engine to idle for a while after a run to allow the turbo to cool down. VW has automated the process to idiot-proof it. I would worry if I did not hear the humming when I turned off the engine.
Click to expand...

I wasn't sure if it was the case. That's why I used to idle the engine for a while. Good thing now I don't have to worry about doing that anymore.
 
J

jeffkro

Go Kart Champion
Location
United States
Fluxion said:
After a run the turbo can get hot. If you just shut off the engine, the remnant heat can cause the oil in the bearings to overheat and essentially burn, turning into a hard deposit (called coke) which is not very good at providing lubrication. As a result, the bearing can fail (bye, bye turbo). To prevent this scenario, the oil pump continues to circulate the oil through the turbo bearings until the temperature has dropped to a safe level at which point it will turn itself off (there's a thermostat) and everything is cool (literally). Years ago, I remember that Saabs, which were one of the early cars to use turbos, told the owners to allow the engine to idle for a while after a run to allow the turbo to cool down. VW has automated the process to idiot-proof it. I would worry if I did not hear the humming when I turned off the engine.
Click to expand...

Using fully synthetic oil should also help as it can tolerate much higher temperatures. Back in the turbo heavy 80's I don't think the synthetic oil for cars was readily available.
 
B

BJJGTI

Ready to race!
Location
On The Mats
Fluxion said:
After a run the turbo can get hot. If you just shut off the engine, the remnant heat can cause the oil in the bearings to overheat and essentially burn, turning into a hard deposit (called coke) which is not very good at providing lubrication. As a result, the bearing can fail (bye, bye turbo). To prevent this scenario, the oil pump continues to circulate the oil through the turbo bearings until the temperature has dropped to a safe level at which point it will turn itself off (there's a thermostat) and everything is cool (literally). Years ago, I remember that Saabs, which were one of the early cars to use turbos, told the owners to allow the engine to idle for a while after a run to allow the turbo to cool down. VW has automated the process to idiot-proof it. I would worry if I did not hear the humming when I turned off the engine.
Click to expand...

+1
 
imthanick_a

imthanick_a

Autocross Champion
Location
Ohio
Sikin said:
Just an update having had a similar problem and having read this thread. I also had a really annoying engine hum/whine above about 1,000 rpm on a 2013 1.6 Bluemotion Tdi. It went into VW under warranty and the mechanic could hear it quite clearly. I mentioned the turbo isolation solenoid that I'd heard about and they basically said that you can't believe everything you read on the internet. However - when they investigated it turned out it was this! They changed it and now the engine is quiet! Thanks Forum!!
Click to expand...
This seems unrelated. The noise this thread is referring to is when the engine is not running
 
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