Heavy Duty Alternator

Delco Remy 39MT™ Heavy Duty Gear Reduction Starter

The 39MT is a gear reduction starter ideal for heavy duty truck and off highway applications. The drive has an electrical soft start that rotates the pinion for proper ring gear engagement before cranking, minimizing tooth abutment related damage. The sealed solid link solenoid eliminates contact welding in low system voltage situations, providing enhanced reliability. Sealed noseless configuration minimizes debris accumulation and contamination reducing maintenance expense.

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Installation Instructions
Service Parts
Important Notice for DD 13/15/16 Applications


Engine Size 12 Volt up to 15 Liters
24 Volt up to 16 Liters
System Voltage 12 or 24 Volts
Rotation Clockwise
Mounting 12 Volt SAE #1, SAE #3
24 Volt SAE #3
Pinion 11 Tooth, 6-8 Pitch
12 Tooth, 8-10 Pitch
12 Tooth, MOD 3 (Metric)
Peak Output 12V 7.3 kW
24V 9.0kW
Battery Internal Resistance 12 Volt 2 mOhm
24 Volt 8 mOhm
Weight 30.8 lbs / 14 kg
Frame Diameter 4.5 in / 114 mm
Overall Length 14.09 in / 358 mm
Motor Type Wound Field
Planetary Gear
Pinion Support Noseless
Drive Design Electrical Soft-Start
Overrunning Clutch
Optional Features Rotatable Flange
Over-Crank Protection
Jump-Start Protection
(meets SAE J1493)
*(US/Canada Only)
3 year / unlimited miles - All Makes
1 year / unlimited miles 


Over-Crank Protection

Over-Crank Protection on the Delco Remy 39MT protects the starter in adverse starting conditions such as cold-weather cranking, lower battery capacity, high-starting circuit resistance or operator misuse. 

Over-Crank Protection (OCP) is a built-in circuit breaker protecting the starter from thermal damage by automatically resetting at a safe operating temperature.

Rotatable Flange

Reduce inventory costs today with the 39MT rotatable flange design. The Delco Remy 39MT Starter’s rotatable flange improves service flexibility and part number consolidation. 

Rotatable flange models easily replace competitive units and provide full industry application coverage of virtually every 12-volt and 24-volt application. By simply removing the flange screws, you are able to rotate the flange and align the starter to the engine.

Electrical Soft Start

The 39MT provides improved starter pinion engagement. Our innovative redefined electrical soft start reduces wear-and-tear by slowly rotating the pinion until it properly engages into the ring gear, before cranking. This also minimizes tooth abutment, ultimately helping to extend starter life.

Two Sided Chamfer

The 39MT Starter pinion tooth lay-back chamfer improves engagement reliability. A double-sided chamfer provides smooth, reliable engagement and reduced wear on ring gear.

Optimum Spline

The Delco Remy 39MT includes several key features designed to ensure the starter reliability. One of those is the ideal number and spacing of spiral spline teeth that provide high strength and smooth engagement. Another is the optimum planetary gear ratio for transmission of high torque and speed. These features work together to ensure the vehicle starts every time.

Advanced Circuitry

The Delco Remy 39MT includes several key features designed to ensure the starter’s reliability. First, the larger gauge motor circuit wire translates to higher current draw and lower voltage drop.

Additionally, a lower resistance solenoid ensures pinion engagement to ring gear. These features work together to ensure the vehicle starts—and keeps running.
Power Rating
The Delco Remy 39MT cranks up to 30 percent faster than the competition, including comparable Melco, and Denso models. 

The 39MT provides the durability and reliability you expect from Delco Remy starters.