screeching noise coming from engine

[rt turbo]

I was thinking it was a bad pulley or bearing. The motor runs fine and still makes normal power, but there is this horrific screaching/howling sound coming from the bay. I think the sound is coming from under the intake manifold but I cannot confirm. It goes away after about 5 mins of driving and its fully warmed up. But even afterbeing warmed up I notice a lower whine like a supercharger gear whine sound. My car is not supercharged. Anyone ever have anything like these symptoms? I searched but found nothing resembling this. Any input is appreciated! Anyone in the Charlotte area care to give help diagnose this? Im preparing the car for my turbo build and need to know what this is to fix it when the head is off for the .140 HG change.

[Balthazarr]

Can you post a vid of the noises?

[rt turbo]

unfortunatly I dont have a video camera.

[Balthazarr]

Then it could be one of several things.
Vac leak; rear main seal leak (vac); noisy alt or belt.
Air pump?

[rt turbo]

Then it could be one of several things.
Vac leak; rear main seal leak (vac); noisy alt or belt.
Air pump?
Doubt its a vac. leak. Unless a line has broken, but it doesnt sound like air, sounds like metal on metal-or some other hard material. I was thinking possibly bad vanos solenoid but I dont think its coming from the front of the valve cover. is there anything that spins wth the motor under the intake manifold? behind the oil filter unit or in that general area? almost looks like it would come from the altenator, but Ive never, ever heard one make this sound. i dunno. Im thinking of spraying some wd 40 in a pulley and see if it stops the sound. lol. i may end up taking it to someone.

[M3vil]

i had an issue when i put the UUC underdrive pulleys on, the belt was rubbing against the idler pulley bracket. pulled the belt off and just used a bow saw blade and cut the bracket back, never made the noise again.

id check there, look behind the belt towards the bracket, you should be able to see it.

[adms1018]

I would try checking your belt and belt tensioner. So I might be new to owning a BMW, but on other cars that I've owned a screeching like that when you start it up can mean a loose belt. Once the engine and belt have had time to warm up the sound would go away, similar to what you're describing. I'm not exactly sure how you would check the belt tension on these cars, but maybe someone with some more expertise can throw their opinion in.

[Xtatic]

do let us know if you find the problem

[rt turbo]

Its not a loose belt sound. more like hard surface to hard surface. or a bad bearing somewhere. Its not internal engine though... motor is in sound condition.

[jengah]

I had the same problem and it frove me nuts. It was a bad alternator bearing. I replaced the alternator and it went away.

FYI - a few months later a ticking/slapping sound came from the engine. Everyone thought it was another bad pulley or tensioner or even worse, internal. Ends up it was just an old belt that had about an inch of rubber missing that made the noise each time it rounded a pulley. My advice. Since you'll be in there, replace all the belts - its easy.

To check if its the alternator bearing or any other bearing, use a long screwdriver like a stethascope.

[theforce19]

I had something like this too. Bugged the hell out of me. Turned out to be the fan clutch. I just took it out and did the fan delete stuff. fixed the sound and no overheating. To check this, you should be able to move the fan by hand when the car is turned off. If it doesnt spin or is really hard to spin its probably the fan clutch. Somebody correct me if im wrong. Don't want to give wrong information.

[rt turbo]

I had the same problem and it frove me nuts. It was a bad alternator bearing. I replaced the alternator and it went away.

FYI - a few months later a ticking/slapping sound came from the engine. Everyone thought it was another bad pulley or tensioner or even worse, internal. Ends up it was just an old belt that had about an inch of rubber missing that made the noise each time it rounded a pulley. My advice. Since you'll be in there, replace all the belts - its easy.

To check if its the alternator bearing or any other bearing, use a long screwdriver like a stethascope.
Great advice! It actually is coming from that area, but its so damn loud I cant get close enough before my ears hurt. LOL. I will focus towards the altenator. And i also have bought all new belts and such... New 80* thermoustat, high performance metal water pump, alum t-stat housing, etc. all going on when the head is off. I will check the altenator this week and post up what I find. Thanks for everyone's input!