Short answer. No, the levy does not jump ahead of an existing mortgage. Rule 39, Section 12 makes an execution levy create a lien only over whatever right, title and interest the judgment debtor actually has, and that lien is expressly subject to liens and encumbrances, including an existing mortgage, that were already there.
What the law says
The levy on execution shall create a lien in favor of the judgment obligee over the right, title and interest of the judgment obligor in such property at the time of the levy, subject to liens and encumbrances then existing.
Rule 39, Section 12 — Effect of levy on execution as to third persons. Read the full provision →
The levy only reaches what the debtor actually owns
An execution levy does not wipe the slate clean and give the judgment creditor first claim on the property. The levy on execution shall create a lien in favor of the judgment obligee over the right, title and interest of the judgment obligor in such property at the time of the levy, subject to liens and encumbrances then existing. If your property already carries a mortgage when the levy is made, the levy attaches only to what is left of your interest after that mortgage, not to the whole property free and clear.
Existing mortgage keeps its priority
Because the lien created by the levy is subject to liens and encumbrances then existing, an earlier mortgage is not displaced or subordinated by a later execution levy. The mortgage continues to rank ahead, and anyone who buys the property at an execution sale takes it burdened by that mortgage in the same way the judgment debtor's own interest was burdened before the levy.
What a buyer at execution sale actually gets
A purchaser at an execution sale steps into the shoes of the judgment obligor as of the time of the levy, no more. That means the sale transfers the debtor's equity in the property, not a mortgage-free title. If the mortgage remains unpaid, it stays attached to the property, and whoever ends up owning it, whether the judgment creditor or a third-party buyer, takes subject to the mortgagee's right to foreclose if the loan is not paid.
Timing of the mortgage matters
The rule protects only liens and encumbrances that existed at the time of the levy. A mortgage created after the levy already took effect would not enjoy the same priority, since by then the judgment creditor's lien would already have attached to whatever interest the debtor still held. Whether a particular mortgage predates or postdates a specific levy is a factual question that depends on the dates involved.