87 GT-S engine knock, spun bearing oil issue? whats goin on

[panish]

o here's the scoop, put a new muffler on my car. (yes, a cheap fartcan) It ran fine for a few days with the silencer in. (It's plenty loud) I take the silencer out and it runs for I'd say 6-10 miles, before the engine messes up badly. I noticed while accelerating quickly right before it [died] that it seemed to have much less power than normal, let off the gas put the clutch in and it stalls. Starts up fine but can not hold an idle, its idling way too low, and stalls. So I drive off, trying not to let it get down to idle at all, and notice that there is a loud tapping or knocking noise with the engine. It seemed to be louder when the gears were engaged. I was only about a mile from my house so I drove it home, accelerating and putting it in gear only when I had to. I have not driven it since then. (Tuesday March 14) so basically the engine is out of whack. It makes a very loud knocking pretty much anywhere over 1500 rpm. And when you first start it, it will idle at 2000, which is normal, and the knocking wont start for several seconds then it comes in, and sounds just awful. I have a video, It is really messed up, the thumping noise is nto really there, I gues my camera is messed up too, but I think you will be able to get the idea from the video.

also, I put the silencer in soon afterwards so the engine was still warm and it can hold idle, so this problem seems to have something to do with back pressure.

and the oil was changed less than 500 miles, ago and is fine.


EDIT mechanic says its OUT OF OIL and beyond reapair, although he did not look at the engine. He said there was no oil on the dipstick, and they put 3 1/2 quarts in. I checked the dipstick the day after it broke, and there was oil on it. It did not leak on to the ground, and I dont think the car burned oil(and it couldn't have burnt it off if it wasn't on). Really confused! Is the engine done? or is there something else that could be going on?

http://youtube.com/watch?v=8FwcChe7Vgo

other info about car

1987 Celica GT-S Liftback

134,000 miles roughly

Mods: custom intake filter (on since december 05), muffler (March 11), Eibach lowering springs(March 2).








AHH SORRY I POSTED TWICE, dont know what happened, I want to delete one, but I dont know how...