you can't borrow more than 50K.

Seems none of the other repliers had ever borrowed.

If you calculated, the money is not worth it as its interest though paid to yourself is after tax, then you need to pay another 401K tax when withdraw. It is too much tax on them.

Hence unless you really need that money to pay off 2nd lien or get a short sale, don't apply it; and repay it as quickly as you can.