Is it the oil pump I hear running? (Page 1/3)
Cliff Pennock NOV 29, 02:30 PM
So today, when I turned the ignition switch to ON (without starting the car), I noticed a "sound" coming from the engine bay. It was a low pitch sound, much like the radiator fan (but much quieter). This was with an engine at temperature (I had driven the car for some 30 minutes and then parked the car for about 10 minutes). I can't remember ever hearing this sound before (and I've had this car for 26 years now).

So what is that? Is that the oil pump? And should it be running even without the engine running?
82-T/A [At Work] NOV 29, 02:43 PM

quote
Originally posted by Cliff Pennock:

So today, when I turned the ignition switch to ON (without starting the car), I noticed a "sound" coming from the engine bay. It was a low pitch sound, much like the radiator fan (but much quieter). This was with an engine at temperature (I had driven the car for some 30 minutes and then parked the car for about 10 minutes). I can't remember ever hearing this sound before (and I've had this car for 26 years now).

So what is that? Is that the oil pump? And should it be running even without the engine running?



The ONLY thing that should be coming on when you first turn the car to the "ON" position, without starting it... is the fuel pump. It's "priming the line" by pressurizing it just before you attempt to start the car. If everything is working well, it SHOULD run for about ~10 seconds and then shut off (unless you start the car, in which case it will continue).


Note, the oil pump is mechanical, and it will only run when the engine is running, because it's fed off either the crank of the cam... but I honestly cannot remember. You would never hear that because it would be practically impossible to separate that sound from the engine itself.
Mickey_Moose NOV 29, 02:49 PM
Just throwing this out there - maybe the trunk fan (alternator and coil)?

I am not familiar with how the trunk fan works as none of my cars have/had it, but since the car was recently driven - maybe??
Cliff Pennock NOV 29, 03:16 PM

quote
Originally posted by 82-T/A [At Work]:

The ONLY thing that should be coming on when you first turn the car to the "ON" position, without starting it... is the fuel pump. It's "priming the line" by pressurizing it just before you attempt to start the car. If everything is working well, it SHOULD run for about ~10 seconds and then shut off (unless you start the car, in which case it will continue).



Yes, it's not the fuel pump.
Cliff Pennock NOV 29, 03:17 PM

quote
Originally posted by Mickey_Moose:

Just throwing this out there - maybe the trunk fan (alternator and coil)?



There's a trunk fan? 😳
Cliff Pennock NOV 29, 03:20 PM
Ok, so apparently, this is the trunk fan (it's coming from the right side of the engine compartment).

The reason I've probably never heard it before is because it should never run alone and only at the same time as the radiator fan. But the radiator fan is not running. So something is not right here.
Patrick NOV 29, 04:59 PM

quote
Originally posted by Cliff Pennock:

So today, when I turned the ignition switch to ON (without starting the car), I noticed a "sound" coming from the engine bay. It was a low pitch sound...



I thought it might've been the sound of your poor suffering Fiero moaning and pleading to have its oil filter changed!


quote
Originally posted by Cliff Pennock Here:

I haven't replaced the oil filter in approximately 15 years, so it's much overdue.


[This message has been edited by Patrick (edited 11-29-2023).]

Cliff Pennock NOV 30, 01:37 AM

quote
Originally posted by Patrick:

I thought it might've been the sound of your poor suffering Fiero moaning and pleading to have its oil filter changed!



There are soooo many "small" maintenance things to do on this car which I would have done long time ago if I had my own garage. Mind you, I have to do everything at the side of the road and this being the Netherlands, we have about 1 month per year that it doesn't rain or isn't freezing cold... The past year, that time was spent on replacing the radiator, heater core and exhaust. The heater core was the last thing I did. A few days later it started raining and it hasn't stopped raining since.

My Fiero is leaking fluid from everywhere - transmission oil, engine oil and coolant. But I have to wait until at least May for the weather to clear up (and temperatures to rise) long enough to work on the car.
Patrick NOV 30, 03:17 AM

quote
Originally posted by Cliff Pennock:

But I have to wait until at least May for the weather to clear up (and temperatures to rise) long enough to work on the car.



Now granted, I did this in a friends yard (and not on the street)... but when I swapped in a 5-spd and replaced the clutch in my '84 Fiero in Decembrrr of 2009, I went to rinse my hands off in a bucket of soapy water we had nearby for that purpose... and I discovered it was frozen solid.

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buddycraigg NOV 30, 06:40 PM

quote
Originally posted by Cliff Pennock:
The reason I've probably never heard it before is because it should never run alone and only at the same time as the radiator fan. But the radiator fan is not running. So something is not right here.



You're coolant issues are wearing me slick.
Is your radiator fan coming on?