cmw0021

iTrader: (1)

Hey guys, Ive had this weird issue for the past year or so. Whenever it gets around winter time, and sub 40 degree temperatures, my '99 z28 gets this loud buzzing/whining sound on a cold start. It lasts for about a minute or two, and then goes away. It seems like this year it lasts substantially longer than it used to (about 20 seconds). I will say that I removed the serpentine belt to rule out any pullies, but it still remains. I checked to see any cracked vacuum lines, but nothing that I was able to fine. It's driving me nuts, and I cant figure out what it is. Whether it being serious or not, I need to fix it. Any ideas what it is? Thanks again.

Video:

http://www.youtube.com/watch?v=MVBXK...ature=youtu.be

SFox

Where's the noise coming from? Might listen close to the fuel pump, and perhaps the heater area?

FU_I_AM_UltraZ

iTrader: (20)

bearings in alternator??? have someone start it up and look for what direction the noise is coming from... maybe ps pump is starting to go out?

cmw0021

iTrader: (1)

So far I've done the following:

-Replace Air Check Valves
-Tighten Manifold bolts
-Removed serpentine belt to confirm if it were a pulley issue
-Checked EGR valve
-Checked all vacuum lines
-Pulled the Air Pump fuse

None of the above resolved the issue. It's weird since it only happens when it's fairly cold outside. Also flutters or changes pitch when I rev it. Once warmed up, it goes away. I do have a P&P throttle body, which im not sure if thats the issue or not. It's definitely coming from somewhere under the hood, but I still cant pinpoint exactly where the sound is coming from.

JDEP162

i wud have said air pump, mine does same thing, but u said pulle air fuse, so, ?

cmw0021

iTrader: (1)

bumpp

Monsoon

I realize this thread is rather old but I'm wondering if you ever made any progress with it. I have a 99 SS and it does the same thing.

I've been through several things as well. I've tried pulling the fuse and relay for the A.I.R. system as well as blocking the ports for that on the exhaust manifolds. It makes it quieter overall but the whine noise will still occur when you get to about 1,500 rpm. I've searched extensively for a vacuum leak. Replaced TB gasket and EGR gasket (into TB). Today I went so far as to pull the intake manifold and look for cracks...didn't see any. I cleaned the surfaces and replaced the 8 intake manifold gaskets. No change.

I have a catch can installed but the sound had existed before and after that so no change there. This is frustrating!

Did you think about the water pump? I can't isolate where the sound comes from but it seems like it's in the front of the engine in the area of the TB and water pump.