: North Star 4.6 Engines-noisier at startup unusual?



teckguy
08-12-13, 08:08 PM
After refreshing all my belts, fluids and filters I am becoming much more familiar with the inner workings of this car. Do these engines make a bit more noise at initial start-up?....say the first 30-60 seconds and then becomes sewing machine quiet? I am experiencing what sounds like light belt noise or even a squeaky bearing type noise but coming from the center back portion of the motor then after a short period totally disappears...injector noise perhaps? My mechanics stethoscope does not shed any light on the issue at all- lifters and valves seem nice and quiet....issue is more on a cold start and not really audible from inside the car....just curious for insight :)

Submariner409
08-12-13, 08:30 PM
Listen around the water pump belt drive assembly - on the driver's end of the left (front) cylinder head. That w/p tensioner pulley is known to have wear problems ......... 100,000 Km on the car ?

Update your profile to show the year and mileage on the car......... There ARE 32 roller cammed valves and associated parts clicking around in there .......

Superjim
08-12-13, 09:32 PM
After refreshing all my belts, fluids and filters I am becoming much more familiar with the inner workings of this car. Do these engines make a bit more noise at initial start-up?....say the first 30-60 seconds and then becomes sewing machine quiet? I am experiencing what sounds like light belt noise or even a squeaky bearing type noise but coming from the center back portion of the motor then after a short period totally disappears...injector noise perhaps? My mechanics stethoscope does not shed any light on the issue at all- lifters and valves seem nice and quiet....issue is more on a cold start and not really audible from inside the car....just curious for insight :)

Mine also makes a LITTLE BIT more noise on the first start of the day for just a few seconds.
I only notice it if it is in the garage and the drivers window is down.

Like SUbmariner409 said... 4 cams, 32 valves, several feet of timing chain, and all the associated stuff that goes with it, is all moving around.

teckguy
08-12-13, 09:56 PM
No only 43,000 KMs...water pump and belt are silent and new serpentine belt makes the left side nice and quiet to. The tensioner is nice and strong with no jerking around usually seen with worn ones and I have not touched the idler wheel.

Submariner409
08-13-13, 10:24 AM
The engine isn't even broken in yet. It needs some judicious exercise. Go up ^^^ in the top black bar and study the entire Cadillac Technical Archive - especially the article "Occasional full throttle operation is good ..............". The articles were written by some of the original Northstar Powertrain design engineers.

TulsaVic
08-14-13, 09:39 AM
Mine also makes a LITTLE BIT more noise on the first start of the day for just a few seconds.
I only notice it if it is in the garage and the drivers window is down.

Like SUbmariner409 said... 4 cams, 32 valves, several feet of timing chain, and all the associated stuff that goes with it, is all moving around.

Ditto. Usually by time I get the seat belt fastened and put it in reverse, the extra "noise" is gone.