12V Starter Motor STG91767 for Case tractors , Massey Ferguson MF-290, MF-298, MF-3050

Overview of the STG91767 Starter Motor

The STG91767 starter motor is a 12V, 3.0 kW unit built for Case tractors , Massey Ferguson MF-290, MF-298, MF-3050. It is a reduction-gear starter with a pre-engaged solenoid, assembled to the original mounting flange and terminal positions so it fits without adapters or wiring changes.

Because the motor is only used in short bursts, heat builds up quickly and escapes slowly. A starter that has worked for years in traffic or on site will show heat-hardened resin, shortened brushes and a pitted solenoid contact long before the windings fail.

Specification Summary

• Rated voltage: 12V
• Rated output: 3.0 kW
• Pinion: 10 teeth
• Type: reduction gear starter with pre-engaged solenoid
• Application: Case tractors , Massey Ferguson MF-290, MF-298, MF-3050
• Net weight: approximately 8.5 kg
• Condition: new, direct replacement for the original unit

A 12V 3.0 kW rating is the output the motor can hold while cranking, not a peak figure. It is sized so the engine reaches starting speed on the first or second revolution, which is what makes a healthy start feel immediate.

The drive end housing is cast aluminium and carries the pinion bearing, so the pinion stays square to the ring gear when the motor delivers full torque.

Reference Numbers and Cross References

Cross references for this starter are listed below. They are a matching aid rather than a substitute for checking the number on the old unit:

• STG91767
• 4.236
• 4270745M2
• IS1098
• AZE4125
• 11.131.984
• 1447834M91
• AZE4214
• AZE4536
• AZE4579
• 4TNV98.776011
• 234987A1
• 3542185M93
• 3667037M91
• 706022A1
• 11.131.112

Where the label on the old starter has corroded, compare the pinion teeth, the mounting flange and the terminal bracket with the photographs before ordering. The number on the original unit is the reliable identifier. This starter is listed with 16 references in total.

Fitment and Application

This starter is used across Case tractors , Massey Ferguson MF-290, MF-298, MF-3050 variants that share the same bell housing pattern. Where the original label is missing, the pinion tooth count and terminal position are enough to identify the correct unit. On Case tractors , Massey Ferguson MF-290, MF-298, MF-3050 installations, access to the STG91767 usually decides how long the job takes.

Vehicles that have had an engine or gearbox replacement may already carry a different starter from the one the catalogue expects, so treat the paperwork as a starting point rather than the final answer.

What Wears Out First

Oil or coolant mist from a leaking seal finds its way into the drive end housing, mixes with carbon dust and forms a conductive paste. The starter then arcs internally and fails early, whatever its mileage.

Most failures start at the solenoid contact. Each start switches the full cranking current through a copper disc, and after thousands of cycles that disc pits and burns. The result is the familiar single click with no rotation, or a delay before the motor turns. The STG91767 ships with its solenoid fitted, so no parts have to be transferred from the old unit.

Symptoms of a Failing Starter

• Click from the solenoid with no rotation, sometimes clearing on a second attempt
• Cranking that has become slower over several weeks
• Grinding as the pinion meets the ring gear
• Starter that keeps running after the key is released
• Intermittent no-crank that appears when the engine bay is hot

Before replacing the starter, check the battery state of charge, the terminal clamps, the engine earth strap and the main cable. On vehicles of this age a corroded earth connection produces exactly the same slow-crank symptom and costs far less to correct. Fitting the STG91767 correctly takes less time than diagnosing the original fault.

Before You Fit the Replacement

• Condition of the old pinion and ring gear before the new unit goes in
• Main cable continuity and the condition of the lug at the starter stud
• Battery voltage while cranking, measured at the battery posts
• Mounting face cleanliness and bolt condition
• That the replacement terminal layout matches the original harness

Most comebacks after a starter replacement trace back to something that was not checked before the unit went on: a tired battery, a corroded earth or a chipped ring gear. Ten minutes with a multimeter and a torch prevents the second repair.

Fitting Guidance

Isolate the battery, mark the terminal positions, then disconnect the main cable and the signal wire. Clean around the mounting flange before the starter is withdrawn so dirt does not fall into the bell housing.

Check the ring gear through the aperture before fitting. Install the new unit with the original bolts, reconnect the cables in the same order and tighten the main terminal without over-stressing the stud. Crank briefly and confirm the pinion releases as the engine fires. Because the STG91767 reuses the original bolts and connectors, no adapters are needed on Case tractors , Massey Ferguson MF-290, MF-298, MF-3050.

Quality Control and Supply from Hejian Nuojin Auto Parts Co., Ltd.

Each production batch is inspected for housing dimensions, terminal integrity and pinion fit, and every starter is bench tested before it is boxed. Units ship in neutral cartons with foam protection, which keeps freight damage low and allows distributors to label stock under their own brand.

Common references are kept in stock for fast dispatch, volume orders are delivered in around 30 days and each starter carries a one-year warranty against manufacturing defects.

Frequently Asked Questions

Can I test the starter on the bench?

Yes. Apply battery voltage to the main stud and the signal terminal and check that the pinion throws and the motor turns. A clamp meter reading against the rated current will show whether the unit is drawing too much.

How do I confirm the starter matches my vehicle?

Read the number on the starter body or on the old unit and compare it with the reference list above. Where the label is missing, match the pinion teeth and the terminal bracket against the photographs.

Why does the starter work cold but fail when hot?

Heat raises solenoid resistance and reduces brush spring pressure. Both effects build up gradually and appear first on a hot restart.

Why does the starter click but not turn?

Most often the battery is low, a terminal is corroded or the solenoid contact is burnt. Measure battery voltage while the key is turned; a healthy battery that still gives only a click points to the solenoid.