mystery squeaking sound

I have 97 blazer 4.3L 4x4 electric. There is a squeaking loud, hard sound coming somewhere inside the motor. I can still turn on the truck without the belt on to eliminate any noise from the pulleys, but the sound it still there . The sound is like when rubbing the aluminum top of a glass soda against the bottle up and down. It starts from the very beginning and does not seem to go away even if you accelerate. I removed the starter, had it checked at auto zone. I first thought of the bandage in the starter but it works fine. they say the starter is very good and there is no way the sound comes from here. The sound seems to come inside the motor. I removed the heads, had them checked for cracks or bends, installed in new head gaskets. The heads were not damaged nor bend. My final thought of this is the flywheel ?? I tried to move it with my hand to see if it was lose or what not, but the flywheel feels tight. I have never messed with it in the first place, so I don't think that is the problem. Are there any sort of bearings in the largest pulley which turns the pistons?? How hard is it to removed and re-install the flywheel?

Hi,
If you have A/T your flywheel can crack right around where the crank bolts are, get a light up in there to check it good. You'll have to look not feel.


I think you saying manual shift into 4x4 instead of elec.
But if manual shift trans, could be the pilot bearing

its electric 4x4, there is a button with 3 lights (2hi, 2low..etc) next to the a/c vent which I can simply press and the truck goes into 4x4...its not manual or stick. Initially, to make the long story short, the truck had about 2 quarts overfill, was throughout the oil not sure from where, but I trained it and refilled the correct amount with new oil. the sound is something rubbing metal..none stop. I'll try to post a video if possible. The truck has not belt, so I was going to try to spin the huge pulley with my hand and see if the flywheel makes some noise instead of having to take off the transmission and check the flywheel. But thats the only thing I believe is spinning..so i might not have an option but take off inspect the flywheel. What does A/T stand for?

Hi,
A/t is Automatic Transmission.
You don't have to pull trans to inspect the flywheel. Pull the cover off underneath the torgue converter.
You will be able to look using a light to see if the flywheel is cracked.

If the engine was 2 quarts overfull you are drawing oil into the engine through the modulator on the transmission.

That can be making what is call a crankshaft whip, I can't remember the name exactly.

There will be a vacuum line coming up from the transmission to the intake manifold on the engine, that is where it is sucking the fluid from the transmission into the engine.

Replace that modulator right away and fill your transmission up.

That can be your whole problem right there.

ok,so yes, it is a A/T 4.3L Blazer 4x4 electric. I will inspect the flywheel and also want to replace the tranmission modulator, but where is that? you mean transmission filter? Do I have to take out the transmission or simply remove the transmission oil pan? The intake manifold it the black cover ontop of the boat where the two silver metal lines of gas go into, is that right? I took off the intake manifold and the boat..I unplug the square plug which feed injectors and two metal pipe to remove the manifold. I don't remember any other pipe coming from the transmission but i'm gonna take a very close look on everything and get back to you tomorrow. For now, i'm searching for the modulator and inspecting the flywheel...
OK..I just saw a black rubber connecting to a black metal pipe coming from the top of the rear motor next to the where the gas lines go attached with a bracket near the distributor. This black rubber pipe connects to a triangle shape black senor ( seems to me) which bolts to the top--passenger side intake manifold and holds down with two small nuts. Is this the modulator you were talking about?? There is also a rubber pipe running along the transmission dipstick. I was told that was for transmission over flow but maybe i'm wrong. Just guide me and I'll get it done.
If i can ask , you say that the truck could be drawing oil into the engine through the modulator on the transmission, but how can that happen if the transmissin oil and motor oil are separate, no? There isn't a direct connection for flow between the transmission and the motor, or do I have it all wrong mentally?

Finally found the problem. I can't believe how much a little leak of air can make a hardcore loud metal-to-metal scraping sound. the problem: The black pipe which connects to the passenger valve cover goes to the top throttle black cover right, well it was not connected on the top and it was half way out from the valve cover. I guess i shirk and grabbed the cover from the pipe when i was removing the cover and pulled out the pipe a little, enough to cause a leak and loud scraping whistling. Thank you very much for your time..