My wife's 4.6 in an Expedition spun a bearing about a month ago. I did a 'cheap' rebuild (actually no such thing with modular parts) including a new crank and rods.Basically went through the short-block and put the used top-end parts back on it. Just got it back in and running, drove a few miles to test/check for leaks, etc. and pronounced it ready to go. Yesterday, she drove it for the first time and the oil light came on less than 10 miles from home. She pulled it into a strip mall parking space and called my daughter for a ride. I went by yesterday afternoon to check it out and there's no oil (not even touching dipstick). I filled it up with 5w-20 and it hasn't got 20 miles on it. I can't find any SIGN of a leak anywhere. I wouldn't think it could burn that much in that short of a time, and even if it did, she should have left a cloud of smoke behind her. It wasn't smoking at all on me, other than a puff or two the first minute it ran. About to go there with my son, fill it up and check it, but this seems WAY strange. (Of course, I have a Taurus that 'disappears' transmission fluid at an alarming rate with no sign of leaks sitting in the driveway - maybe it caught the same disease). Any ideas, anyone?

 

I would say possibly the pcv valve but to lose that much oil would cause tons of smoke.

 

Was there enough oil to start with?

 

Yep, filled it up, and no, I didn't see any smoke at all. I since have filled it up, drove it home and been watching it. So far, so good, except the 5w-20 would lose pressure at idle when hot, despite having all new crank, bearings, etc. I've put in 10w-30 and so far, it's ok. Just don't get where the first 5 quarts went.