In my experience, you can't get a loan on an employer sponsored 401(k) if you no longer work for the employer that sponsor's the plan. But that's just my experience.
When I parted ways with my employer, I had something like 60 days to transfer my 401(k) to either an IRA or another 401(k). If not done in time, then they cut me a check and the entire amount is taxable and if under retirement age, also subject to the 10% early withdrawal penalty.
At least, that's how the plan I was in, worked.
