Engine is stuffed. The knocking sound is the con rod bearings beating themselves to death. There is likely other damage in there as well. The mechanic can't tell you exactly what's stuffed, but from experience he knows it's munted. Maybe he could replace just the main and big end bearings, then 3 weeks later the cam bearings crap out, or it starts burning oil, and you are back wanting it fixed uner warranty.

The suggestion of swapping it for a new or fully rebuild engine is a sensible option. You can try shopping around or look for a good used engine.

30 sec of google-foo brought up this.

http://www.ebay.com/itm/Grand-Cherokee-E...

You still need the mecahnic to fit the engine, but this way you might get it done for $3,000

But bottom line is that running an engine without oil WILL kill it. Expensive lesson there.

no oil in engine? did you pay this mechanic for a complete tear down of engine so all pieces could be inspected? I can assure you if there were knocking noises it wasn't necessary to do so. main bearing rod bearings were damaged. cylinder walls were damamged and so were pistons and wrist pins.

IN OTHER WORDS THE ENGINE IS DONE BROKE!!!

SO SOMEONE MADE AN ERROR AND DIDN'T PUT OIL IN AN ENGINE AND RAN IT UNTIL IT FAILED AND YOU WAN O BE MAD A HE GUY WHO DOESN' HAVE XRAY VISION?

Might need new engine or heads depending on how long he rode it and how hard valve ig u hear a lound nocking it most like bottom end damage if u hear valve tapping u might be in luck and need heads. But the person who answered the first one is right. Bearings need lunrication and if those bearings got warped if might be dun. If so get rid of it beacause jus labor alone will rale ur pocket.

If neither of you are able to read the dip-stick and top-off the oil when needed, the engine has been damaged with NO oil in the crankcase.

Er, once you drive an engine without oil and wreck it, no amount of oil will save it. $5,000 sounds like a lot, but no matter what, it will be a very expensive repair.

If it was driven without oil, the engine is probably toast. $5,000.00 is probably close to what a new engine plus instillation will cost. A short block straight six will be about $2500. Plus.

If there was no oil in the engiene then it probably seized up, which yes means he will need a new engiene.

Your brother is an idiot. Stupidity can be expensive.

I know it sounds stupid but yes my brother didnt put oil in his jeep (v6) 08 the engine started makeing a bad sound so it was taken in to a mechanic. He said it would be $5,000 when asked what was wrong he said it needed a new engine when asked what exactly whent wrong and exactly needed replace ment. He said "no oil was in the engine and it broke" i asked a couple times and i couldnt tell if he just wasnt the guy that checked it out or he was trying to pull a fast one saying we needed a brand new engine or if all i need is oil? What do u think? Could it possibly be i just need to fill it with oil? Thanks