4996706 Starter Motor – Verified Fitment for Cummins 4B3.9 6B5.9

Variant-Level Fitment — every CM build code checked against 4996706 before shipment to prevent flywheel housing mismatch.

Technical Specifications

Application Suitability

Why the Same Part Number Ships Across Dozens of Cummins Builds

Ordering by number alone does not guarantee the starter will bolt on.

Starter motor part numbers have been superseded multiple times across Cummins engine generations. The base identifier 4996706 appears in service manuals spanning the B, ISB, and QSB families, yet the physical differences between a QSB4.5 CM2250 EC variant and a QSB5.9 CM850 variant are real enough to prevent installation. Mounting bolt spacing, solenoid clocking position, and drive gear engagement depth all shift between builds. I once watched a crew spend four hours trying to fit a starter onto a QSB5.9 only to find the mounting lugs were offset by a few millimetres — the part number was correct on paper, but the CM code told a different story. [NEED_CITE: Cummins engine control module variant identification practices]

Starter Motor 4996706 cross-reference lists online often merge all these variants into one line, which is how wrong units end up on the wrong flywheel housings.

Decoding the CM Build Code for Exact Match

Each Cummins engine carries a specific CM (Control Module) build code stamped on the dataplate. Codes like CM550, CM850, CM2150, CM2250, and CM2350 dictate which starter variant physically fits. A Starter Motor 4996706 for a B4.5 CM2350 B146C is not necessarily the same housing or solenoid layout as one for an ISB6.7 CM2250. We pull the CM code from your engine serial or dataplate photograph and match it against our fitment database before releasing the unit for dispatch. This eliminates the trial-fitment gamble that leaves machines sitting idle while a return ships back across the country.

Mounting Flange and Drive Gear Engagement

The 10-tooth drive gear must mesh precisely with the flywheel ring gear at the correct depth. Too shallow and the teeth skip during cranking; too deep and the starter binds under load. On Cummins 6B5.9 and 6C8.3 applications, the flange bolt pattern and nose cone length vary between early and late production blocks. Verifying the physical dimensions against your removed unit — bolt hole centre-to-centre distance, nose cone protrusion, and solenoid terminal clocking — is the last checkpoint before the unit goes in. [NEED_CITE: starter motor flywheel engagement depth standards for diesel engines]

Understanding the Superseded Number Trail

The cross-reference numbers 4280007090, 4280007091, 4280007092, 4380003110, and 5128000980 (reference only) each map to different production runs and engine families. A unit originally ordered under 4280007090 for a QSB4.5 CM850 may now carry the 4996706 designation, but the reverse is not always true — the newer number does not automatically substitute into every application the older number covered. We trace the full supersession chain and confirm which specific engine serial ranges each number serves, so you receive a unit that fits rather than one that simply shares a catalog line.

What Happens When the Fitment Is Wrong

A misidentified starter does not just waste a purchase — it extends downtime. The machine sits while the incorrect unit is removed, repackaged, and shipped back, and the correct unit is sourced and delivered. On a mining site or port logistics operation where a single excavator or loader is critical path equipment, those extra days compound into meaningful production losses. Worse, a starter that almost fits — mounting bolts align but the drive gear engages at the wrong depth — may crank the engine initially and then fail under thermal stress, damaging the flywheel ring gear teeth in the process. That turns a single-component replacement into a flywheel teardown. [NEED_CITE: flywheel ring gear damage caused by incorrect starter engagement]

Verifying Electrical Compatibility Across the B and QSB Range

A 12V system with a 10-tooth drive gear is the common thread across all listed Cummins applications, but cranking amperage demand rises noticeably from the 4-cylinder B3.3 through the 6-cylinder QSB6.7. The starter must deliver sufficient torque to spin the larger displacement engines through compression without voltage drop stalling the solenoid. Solenoid terminal type — typically a stud post with specific thread size — must match the existing battery cable lug. A mismatch here means fabricating adapters on the shop floor, which introduces resistance and potential failure points in the cranking circuit.

How Identification Works Without a Readable Dataplate

In the Pearl River Delta warehouse, I have handled plenty of starters where the nameplate was corroded beyond reading or painted over during a previous overhaul. When the only starting point is the machine model — say a wheel loader with a QSB6.7 — we cross-check the machine serial against engine factory records to pull the CM build code. From there, the correct starter variant narrows down. Photographs of the removed unit, particularly the mounting flange profile and solenoid position, serve as a secondary verification layer. This two-path identification process catches the mismatches that catalog lookups alone miss.

Why Buyers Request a Sample Before Fleet Orders

When standardizing starter inventory across a mixed fleet of Cummins-powered excavators, bulldozers, and loaders from different equipment OEMs, a single incorrect fitment assumption multiplied across dozens of machines represents significant risk. We support sample-before-bulk ordering so that one unit can be physically fitted, cranked, and confirmed before the full quantity ships. This is particularly relevant when a fleet spans both early CM850 and later CM2350 variants of the same engine family, where external appearance is nearly identical but internal build differences dictate distinct starter configurations.

Documentation & Verification

• Dimensional check on mounting flange bolt pattern and drive gear tooth count before dispatch
• Cross-reference verification sheet listing all applicable superseded numbers (reference only)
• Engine CM build code confirmation included with shipment documentation
• Quality inspection record covering no-load cranking test and solenoid function
• Packing photographs showing protective caps on drive gear and terminals
• HS code and customs classification support for international shipment

Fitment Check Before Installation

• Measure bolt hole centre-to-centre distance on the mounting flange against the removed starter
• Confirm drive gear tooth count and engagement depth match the flywheel ring gear specification
• Check solenoid terminal orientation matches the existing wiring harness routing path
• Verify overall length clearance within the engine bay before final tightening
• Compare nose cone profile and diameter with the old unit side by side
• If any dimension does not match, halt installation and contact us with photographs for re-identification

Share Your Engine Details for a Confirmed Match

Provide your Cummins engine model, CM build code, and serial number — or send a photograph of the engine dataplate and the removed starter. We will return a confirmed fitment assessment with the correct variant identified and cross-referenced against all applicable superseded numbers. If your nameplate is unreadable, the machine model and a few photos of the old unit are usually enough to complete the identification.

Frequently Asked Questions

Q: How do I confirm this starter fits my specific Cummins engine build code? A: Send us your engine serial number or a clear photograph of the dataplate showing the CM build code (e.g., CM2250, CM2350, CM850). We cross-check the serial range against our fitment database and confirm which starter variant matches your exact engine build before shipment.

Q: Are the cross-reference numbers like 4280007090 and 4380003110 interchangeable across all engines? A: Not universally. Each cross-reference number maps to specific engine families and production periods. Some substitutions are valid only within certain CM build codes. We verify the full chain against your engine serial to confirm which numbers apply to your application.

Q: My old starter has a completely different part number — how do I verify the replacement? A: Photograph the old unit from multiple angles, especially the mounting flange, solenoid position, and any remaining label fragments. Combined with your machine model or engine serial, we can trace the supersession path and confirm whether Starter Motor 4996706 is the correct current equivalent.

Q: I only have the machine model, not the engine serial — can you still identify the right part? A: In many cases yes. We cross-reference the machine model against known engine installations to narrow down the CM build code range. Photographs of the existing starter help confirm the exact variant. This two-step approach catches most mismatches before the unit ships.

Q: Can I get a sample to check fitment before ordering for the whole fleet? A: Yes. Our minimum order is one piece. We recommend ordering a single unit for physical fitment and cranking confirmation on one machine before committing to a fleet-scale quantity, especially when your fleet spans multiple CM build variants.