REVERE – Two of the city’s fire engines and a ladder truck have aged past their recommended operating life and are saddling the city with big repair bills and potential risk to firefighters.Mayor Thomas Ambrosino plans to reduce the $1.7 million price tag for three new trucks with a $150,000 donation from the Stop & Shop grocery chain and other city payment sources, including money Revere receives from a surcharge on rental cars parked near Logan Airport.The new trucks will be operating by this summer if the city orders them in the next month.Buying a new ladder truck from firefighting vehicle maker Pierce Manufacturing will cost the city $849,000. Fire Chief Eugene Doherty wants to assign the ladder to the new fire station under construction on Revere Beach Parkway.It will replace Ladder 1, based at Walden Street, and the new engines, which cost $423,000 each, will replace Engine 3 based in Beachmont and Engine 5 assigned to the Freeman Street station.Fire Chief Eugene Doherty said the city bought Engine 3 in 1989 and, under safe operating standards set by the National Fire Protection Association, should have replaced the truck in 2000.The city bought Ladder 1 in 1990 and should have been replaced it under Association standards six years ago. The city purchased Engine 5 in 1995, but Doherty described it as a “lesser-type model that has not been able to take the rigors and frequency use that this department requires.”Doherty said operating the three trucks past their recommended operating life has increased Fire Department fuel costs and saddled the department last year with a $19,000 emergency repair bill.He also said Engine 3 and Ladder 1 are not equipped with enclosed cabs designed to protect firefighters from falling from trucks. The town of Brookline is being sued in the wake of a firefighter accident involving a truck operating without an enclosed cab.Doherty wants to assign the new engines to Freeman Street and the North Revere fire station being built next to the Overlook Ridge residential development.