Jazsun

LAtely I have been starting my car in the morning when its real cold outside (it sits outside) like 10 degrees today. Right when it kicks over I hear a loud buzzing noise for like 5 seconds no clue what that is. THen I hear womthing rattly randomly every few seconds until the car warms up or I being driving it. It never made this rattling noise coming from somewhere in my engine bay/wheel well. any help?

n2ceptor

The buzz could be the fuel pump priming the system... And the rattle might be rocker arm tap??????? from the oil being so cold??????

Jazsun

Yeah I think it may be the fuel pump its being loud as hell tho, maby its not but it sounds like it coming from the engine bay sounds like an electrical fan buzz. The tapping isnt a rocker cuz I know what those sound like, it sounds like lower engine bay rattle.

MyShibbyZ28

It is not the fuel pump, the buzzing noise is the power steering. I did the same thing, except in 0* weather, and mine also makes a buzzing noise until it warms up. Our minivans do it also. I think the steering fluid gets so cold it ends up getting some air trapped in there, causing the whining sounds. Ever ran a car that is low on power steering fluid? Makes the exact same noise. Also made that noise when I flushed my power steering and it had to work the fluid back in there. Nothing to worry too much over, just needs to get back up to operating temps.

The thumping noise could be the rockers like n2ceptor said. It might take a few minutes for the oil to get to working temps and get thrown back up into the heads. Also, I wouldn't worry too much about that unless you are flooring it right as you start it.

RedRyder518

How bad really is these cold starts on cars? I know that its the time of most engine wear, but I just feel like my car screams every time I start it when its cold out. Ever notice it seems to take a couple of seconds for the oil pressure to build up? Not very comforting to me

MyShibbyZ28

1: the oil pressure in these cars are always low, unless under throttle
2: The reason it is low, is from the oil not being as viscous. It needs to warm up a bit to get thrown around and build up pressure, otherwise when it is cold, it is not going to move as fast. Plus, more heat=more pressure, lower the temp, lower the pressure. Ever wonder why driver manuals say to inflate a cold tire, instead of warm?

NeverEverSatisfied

If it is a "rattle" then wouldn't you suspect a heat sheild? Just my 1/64 of a cent.

OBE1 95Z28

Quote: The reason it is low, is from the oil not being as viscous. It needs to warm up a bit to get thrown around and build up pressure, otherwise when it is cold, it is not going to move as fast. Plus, more heat=more pressure, lower the temp, lower the pressure. Ever wonder why driver manuals say to inflate a cold tire, instead of warm?

You have this backwards; cold oil is more viscous (thick) and has a higher oil pressure. As the oil warms up, both oil viscosity and oil pressure will drop.

Jazsun

I duno wtf the rattling is but I know my old Taurus did a similiar thing when I would start it in the morning its fairly loud rattle like a washer on a pipe rattling up and down, but its not constant and kinda random comes in 2-3 second burst. Sounded like it was coming from the side of the engine by the tire well. I will investiage tommrow.

RacingTiger04

if u still have the stock manifolds then i would suspect the heat shield like someone else said.. cause mine started makin that same noise awhile back and had me scared to death cause i thought it was a rocker the first time it did it (while i was inside the car anyway)

Z28LT1_Just_Nasty

Completely different engine, but my f-350 powerstroke has a buzzing sound when running not under load when it's really cold out. I couldn't figure it out but doesn't seem to affect anything.

Jazsun

hmmm they are stock manifolds but why would they only shack/bang/make noise in the cold? Ive never heard this before.

MyShibbyZ28

Engine is colder and shakes more. I noticed when my engine warms up it doesn't shake as much.

Guest47904

Do you still have cats? If so try tapping them with a hammer. See if you hear the rattle.

Jim D

I had the factory muffler on my truck replaced with two mufflers from Summitt and it now has a rattle at low rpm's when cold also. And it comes and goes cyclically (is that a word, cyclically?). Maybe something in your exhaust is a little loose...

If I put some pressure on my tailpipe, pushing it down a little, the rattle stops. Maybe you can 'feel' around for a vibrating/rattling component. Just use a long screwdriver or something to touch stuff that may be hot....