but if it was the alternator, the car would've turned on when we put the new battery inside. The battery wouldn't have lasted so long though, because it wouldn't have been getting any charge from the alternator.

Have you tried turning over the engine by hand?

the reson why i said scratch and mentioned the others. is you have 15-30 minutes of run time when a alternator goes bad. also the other battery could have not been up to snuff what i mean have 12 volts and 5ca(cranking amps) and 3cca (cold cranking amps) and didnt have enough to start it there is a safty program in the computer that prevents any damage to the engin and its electrical when there is a problem like a voltage and voltage and mechanical issue. i would check every thing out as in take your battery to auto zone have them check and charge it and see if it starts. then if it does rent a belt tentioner tool remove the altinator and have it checked. i am sorry if i sound angery i dont want to see some one getting ripped from a shop claming it is the engine when they put it together from head work. unless they seen internal damage on the cylender walls when they did it and seen some one that they can get money from dont forget lemon laws. on top of that chevy has a 100,000 mile 10 year power train warrenty take it to the chevy dealer. if it is under 100k take it to the dealer and they will fix the engine and power train. i just want to look out and meantion that

If it was already knocking- the engine was already probably toast, and it just ran long enough for you to finish it off- what about the guy that sold it to you, won't he work with you? Also, the other thing I'm wondering- if the thing was just in a shop with the heads off- why was the oil so dirty? It is VERY easy to spill coolant into the oil valley and return holes when taking the heads off (heck, even just the LIM)- they should've changed the oil once the heads were back on as a precautionary measure regardless. Water in the oil could've easily caused the engine to lock up.

If it seized due to an oil problem- I'd scrap the whole bottom end- regardless if the passages were plugged up, or coolant got in it- all the bearings will be toast- crank, cam, rods, even the wrist pins might be damaged.

That's not really possible on a 3800. The oil pump housing sits in the front cover around the crankshaft snout- and the actual pump rotor is driven directly off the crank snout. There really is no way for it to just stop working (ie like you broke the teeth or driveshaft on an old oil pump). Really, the crank snout would almost have to break off for the oil pump to stop, and that's not really possible.

X2, easiest way to tell if the engine is toast. If it won't budge, the bottom is probably f'd.

Not in 02 they didn't- I don't think that started until 07 (plus its 5 yr 100k isn't it?)

ok sorry i took so long to write back guys.I've been focusing on getting my monte running again. Well so far, we've taken out the engine and when we removed the oil pan, there was a bunch of broken metal. A piston, rods, crankshift and basically the whole core was shatter. So now im looking for an engine or a new core.

does anyone know if a 98/99 oldsmobile 3800 engine can be a direct swap for my monte? A dismantler is selling one for 400 and so far thats the only one ive found in my price range.

hay bumpin i didnt know the oil pump for the 3800 were set up like that thanks for the info. i never opened up a 3800 they are pretty much reliable and also pretty potent stock when they are loved. i have seen most be pretty beaten but still be running like nothing is wrong. sorry for changing the thread

Bottom end and all will be the same- its when you get into engine mounts and accessories that you would run into problems; but you can always use those off your old engine.

so bumpin96 was right. The engine was already toast since i got it.
The whole bottom end was f'd and in pieces due low oil pressure or the oil pressure went out
i went to a nearby junkyard and found a 3800 engine from an impala w/out the intake manifold and a few other parts and it costed me around $200 with 1 yr warranty
we replaced all the gaskets and degreased the whole engine
and i barely got my car back right now and it runs like a champ!
I'm so happy!
i will post pics of the process a little later

Thank you everyone for your help and support!