School probers have busted a long-running custodial “no-show” job scam in which at least six dirty workers allegedly cleaned out city coffers of more than $600,000.

Probers say suspected ringleader Trifon Radef — who was also nailed for using underling, on-the-clock janitors to renovate and landscape his personal rental properties — created the lucrative ghost jobs for himself and four buddies.

Radef, a 36-year veteran custodial engineer at Roosevelt and Truman high schools in The Bronx, would pay his pals in cash part of the salaries they were drawing for the no-show work — and keep the rest for himself, authorities said.

Each of those gigs netted more than $100,000 for the group at least since 2007, officials said.

In addition, Radef’s own no-show job paid him at least $70,000 between 2007 and 2010 for more than 3,000 hours that he clearly didn’t work — because E-ZPass road-travel records prove he couldn’t have, according to Special Commissioner of Investigation Richard Condon.

Additional reporting by Len Maniace