The Marathon MM350DT is the high-capacity gravity-discharge model in Marathon’s mastic mixer range. It carries the same engineering as the MM250DT but adds 100 gallons of working volume, making it the choice for contractors and public works departments running mastic as a core service rather than an occasional repair method.

Capacity is the practical differentiator. Mastic repair is material-intensive, and on larger jobs the constraint is usually how often the crew has to stop and reload. At 350 gallons, the MM350DT extends production between refills, which matters most on municipal road programs, bridge deck joint work, airport aprons, and large commercial lots where a crew is running mastic all day. It also suits operations running two applicators off one melter.

The heating system is Marathon’s oil-jacketed double-boiler design. Heat transfer oil surrounds the material vat, so the burner never fires directly on the material tank. That gives even heat distribution throughout the load and protects the steel, which is why Marathon’s own specifications reject direct-fire and air-jacketed construction for mastic. Engineered hot airflow through the firing chamber shortens heat-up time and reduces fuel consumption, and ceramic insulation limits heat loss so the burner cycles less to hold temperature on a larger charge of material.

Agitation carries over from the 250 and is arguably more important at this size. The full-sweep horizontal agitator uses angled paddles and runs both forward and rearward, drawing material through the vat rather than lifting it off the floor the way many competing units do. On a 350-gallon batch of aggregate-filled mastic, that active movement is what keeps mix consistency even from first pour to last. Agitation direction and speed are controlled at the hydraulic manifold with lever controls and an analog pressure gauge.

Temperature is managed by dual digital thermostat controllers that regulate the material and the heat transfer oil independently against user-defined setpoints, with calibrated analog dial thermometers at the rear for a direct read at the discharge. Overnight heaters keep material warm between shifts so crews are not waiting on the machine in the morning.

Discharge is by heated gravity chute. The chute pivots side to side for a greater pouring radius and stays heated so material flows cleanly out of the unit instead of chilling and dragging at the spout. Loading height is kept low deliberately, so operators can load material blocks into the tank without stepping up onto the trailer, and the tool heater box is sized to take larger application tools in and out easily.

Power is a 23 hp three-cylinder, water-cooled, direct-injected Tier 4 Final diesel engine with electric start and full auto-shutdown protection, paired with a 340,000 BTU diesel burner. Burner, engine, fuel, and hydraulic reservoirs are all positioned for easy service access, which matters on a machine expected to run daily through a full maintenance season.

Construction is minimum 10-gauge steel throughout, fully welded, on a heavy gusseted 6-inch channel frame, finished with epoxy primer and a urethane topcoat. Marathon backs the machine with a two-year unlimited-hours warranty and five years on the trailer frame.

For Canadian contractors bidding larger mastic programs and for municipalities standardizing on mastic for rut and joint repair, the MM350DT is the volume option in the lineup. Roadly supplies and supports the full Marathon mastic trailer range across Canada.