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LT1 Cold start noise?

2326 Views 16 Replies 6 Participants Last post by  N0DIH
I am working on figuring out a startup noise that started once it got cold. It is definately a dry bearing noise, connected to the accessory belt, and now that I have replaced the alternator front bearing, so I have ruled it out. It sure sounded like it was coming from there. The tensioner pulley is so far down and the noise is coming from (seems like at least) farther up and towards the pass side I don't think that is the noise source. The only things left are AC (seems noise is coming from higher) and the idler pulley. Are they common failures? Does the water pump make startup noises when it is getting bad?

Anyone have any experiences?
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Hmm what kind of noise is it?

is it possible for a belt related item to only make noise on startup

I had a similar problem last year in the winter i would get a slight knock when i first started up the car. It went away on its own I don't know if it was oil related. I use 5w-30 all year round

Noise. If that helps! I can try to record it and post it. It is a deep buzzing that is running and engine speed. Once the engine runs for a min or 2 it goes away. Sometimes revving it up helps make it go away sooner.
Oh, I am running Rotella T 5W40 Synthetic right now....
The most common souce of noises in the winter would probably be the P/S pump.
It sounds to be the pulley (idler?) that is next to the alternator, just to the right of it, the big 5-6 inch pulley.
N0DIH said:
It sounds to be the pulley (idler?) that is next to the alternator, just to the right of it, the big 5-6 inch pulley.
The bearing itself, or just a slipping belt noise?
N0DIH said:
It sounds to be the pulley (idler?) that is next to the alternator, just to the right of it, the big 5-6 inch pulley.
Yeah, that sounds like the P/S pump, it's 5-6 inches and just below the alternator.

The idler pulley is only like 3 inches in diameter and is a commonly known "crap" part..... although my two LT1 vehicles haven't had an issue with it.

Good luck tracing down the noise.
Is it a sign of pending failure, or will it just be annoying in the winter months? It goes away within 1 min, but is darn embarrassing on a Cadillac!
Katshot said:
The bearing itself, or just a slipping belt noise?
Bearing, no slipping squeals or anthing. Deep resonant BBBBBBBBBBBBRRRRRRRRRRRRRRRRRRRRRRR sound. Changes with RPM and then starts to get quieter.

It starts around 2-3 seconds after cold start. Warm restart is no issue.

The sound seems more like the alternator, but definately (now that the shroud is out of the way) the pulley just down and towards the right of the alternator.
Something else to look at is the crank pulley, I had the outside part
slipping from the inside (they are separated by rubber) put a spot of white paint on either side of the rubber and look at it in a day or two, if they are
not still lined up replace the pulley(balancer).

The colder the longer I hear it. Now that it is up to 29 or so (heatwave!) it is only 10-15 seconds long.

I will take a look, that is a good idea for any car to keep track of.

I'm gonna have to say P/S pump also... Its probably goin on ya... Check the P/S fluid level just to make sure its right. When you first start the car move the wheel Back and forth and see if the pitch of the noise changes...
It does a bit. I figured it was from rpm of the engine changes.

PS fluid is ok, was a perpetual leak of the steering box main shaft (sector shaft?), so I dumped in some Lucas PS stop leak and it actually did as advertised! I was shocked, that isn't "normal". This is after 3-4 quarts of everything else under the sun that claims to stop leaks....

Maybe time to look closer at disabling the EVO power steering now....
Interesting result found today.

A couple days ago I added some ps fluid for the first time in months. (yes, the lucas stuff helps leaks in the box). It was just a little low, so I added some. the cold start noise got worse, and much longer, won't go away quickly.

So today, I started it up, cold (18F) and decided to check the fluid engine running and the moment I broke the seal on the power steering resovoir cap, it stopped. Dead silent.

Is there a vent in the cap that might be plugged? I have never seen a bad PS cap like this.

what I'm beginning to suspect is air in your ps system because when it was leaking it's possible some air could have gotten in there in daily driving and if you never bleed the system that could be it?

Worth a shot if you never bleed the system you have to figure fluid can leak out as easily as air could be sucked in through the leaky area.
Actually I checked it again today at lunch. It is NEGATIVE pressure, it is sucking hard to keep the cap on. Once you break the seal, all noises go away.
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