: What gives the Northstar its "whirring" sound at idle?



iroc86
10-21-07, 03:07 PM
At idle, the Northstar engine does not sound like any other car I know. Most vehicles are very "mechanical" while standing near the engine compartment, but the Northstar has more of a purring/whirring noise (plus the clicking fuel injectors).

I've been around many Northstar-powered Cadillacs and they've always made that trademark noise. Being a mechanical engineer, I'm curious which engine component is responsible for the sound. It seems to come from the area around the valve covers, but usually the valvetrain makes a distinct noise different than what I'm hearing. Any ideas?

JimD
10-21-07, 03:24 PM
I've convinced myself it is the timing chains you can hear at idle. Blended in with the fuel injector solenoids.

med
10-21-07, 03:29 PM
I've been told it's the alternator. I believe it, although sometimes when I'm delusional I like to think it's one of those superchargers GM forgot to remove after testing!:cookoo:

Submariner409
10-21-07, 03:57 PM
3 timing chains, lots of gear teeth, and 32 cam followers......and an alternator in the front of the engine.

AJxtcman
10-21-07, 04:11 PM
I've been told it's the alternator. I believe it, although sometimes when I'm delusional I like to think it's one of those superchargers GM forgot to remove after testing!:cookoo: If you are around sometime I should take a listen to it. I Can turn off the Alternator and see if it stops. A alternator should only make that noise for a short time.


At idle, the Northstar engine does not sound like any other car I know. Most vehicles are very "mechanical" while standing near the engine compartment, but the Northstar has more of a purring/whirring noise (plus the clicking fuel injectors).

I've been around many Northstar-powered Cadillacs and they've always made that trademark noise. Being a mechanical engineer, I'm curious which engine component is responsible for the sound. It seems to come from the area around the valve covers, but usually the valvetrain makes a distinct noise different than what I'm hearing. Any ideas?


Listen to the P/S pump with the cap off

iroc86
10-22-07, 01:20 PM
You guys are right; it's probably the timing chains. I forgot how loooong they were! Never owned an OHC engine until now.

AJxtcman, it does kinda sound like a power steering pump noise, but mine is as quiet as ever. I've replaced enough of those on my Jeep -- it's nice to have a car that doesn't whine all the time! :)

Submariner409
10-22-07, 04:56 PM
Just for grins and kicks, take a LONG screwdriver, press the handle tip against your ear, and carefully place the metal tip on the part (the stationary part..) next to what you want to hear. Magic.

If you're really fringe material, buy a cheap stethoscope at the corner drugstore and use various lengths of rubber tubing to listen.......

There is no sound on earth quite like a DOHC V-12 Ferrari at 7,500 rpm......

DIXIEDOG
10-23-07, 11:28 PM
Fuel Pump??? Seems to be a good cause for whine on GM pickups, could be the same pump used on Cadillacs.

iroc86
10-24-07, 12:27 AM
Fuel Pump??? Seems to be a good cause for whine on GM pickups, could be the same pump used on Cadillacs.

I know exactly what you're referring to... it IS loud on some of those pickups. I'm referring to the noise the engine itself makes (standing in front of the car).

dkozloski
10-24-07, 12:39 AM
It might be Charles F. Kettering spinning in his grave.

iroc86
10-24-07, 12:49 AM
It might be Charles F. Kettering spinning in his grave.

So THAT'S the reason behind the other distinct Northstar sound -- the starter! ;)