Had a new engine put in my '85 suburban about two weeks ago with about 40k miles on it. Compression test was perfect and it was ex-military so I was confident in it. Anyways, a few days ago it started making a noise like a bunch of screws in a blender, grinding and rattling. I checked the oil and it was fine. The engine will crank up after a few tries but will start making that noise as soon as it kicks on. This may be one of things that you have to hear/see for yourself to get an idea but just thought I'd check to see if anyone had any ideas before pull the engine or tow it to a mechanic. I'm really hoping it's not the engine but that's what I suspect. Any help would be much appreciated!

 

Have a look at the balancer on the crankshaft.
If it has become un-bonded it may be rattling against the drive pulley?

 

Also, If its an automatic, check your torque converter bolts and make sure they havent come loose and backed out a bit. Happened to me when I had an 80 chevy c3500 dually. Just a thought........

 

It doesn't sound like something is loose. Not saying it couldn't be a loose bolt or something but it's pretty loud and whatever it is, it was enough to cut off the engine when the problem initially happened.

 

Can you possibly post a vid of the issue, so we can hear it? That may help a bit.

 

What part of the engine do hear this noise coming from?

 

It's hard to tell where it's coming from while in the drivers seat and I'm afraid to leave it on long enough to get out and listen. If I had to guess it sounds like somewhere between the engine and transmission. I'll put up a video as soon as a figure out how to post one on here

 

a second pair of ears will help. Have a buddy or other listen while you start it or you listen while another starts the engine.

 

Sounds like maybe flywheel ring gear seperation

 

Chevy 6.2 Diesel Trouble! Help!: http://youtu.be/jwQ7KCPalgQ