Product Description:
Hawks Motorsports is pleased to offer our clients the following.
This new genuine GM Original Equipment harmonic balancer, part number 12684590, is a replacement crankshaft vibration damper for select Chevrolet, GMC and Cadillac truck, SUV and van applications. It is designed for the specified factory crankshaft damping and serpentine accessory-drive arrangement. Applications include certain 4.3L V6, 5.3L V8 and 6.2L V8 engines. Confirm the vehicle VIN, engine RPO code and original accessory-drive configuration before ordering.
| Producer | GM Genuine Parts |
| Condition | New genuine OE |
| Product | Crankshaft harmonic balancer / vibration damper |
| GM part number | 12684590 |
| Previous GM numbers | 12620312; 12662037 |
| Engine applications | Select LV3 4.3L V6, L83 5.3L V8 and L86 6.2L V8 configurations; verify VIN and RPO |
| Drive belt type | Serpentine |
| Pulley groove quantity | 13 total grooves, as cataloged |
| Keyway | Yes |
| Outside diameter | 7.8 in / 198 mm |
| Inside diameter / bore | 1.5 in / 38 mm |
| Catalog depth | 1.1 in / 28 mm |
| Mounting hole quantity | 1 |
| Catalog mounting hole diameter | 1.48 in / 37.61 mm |
| Center bolt thread | 16 mm / 0.63 in; coarse, as cataloged |
| Catalog center bolt length | 103 mm / 4.06 in |
| Bolt and washer included | No |
| Sale quantity | One balancer assembly |
| Year | Cataloged application / required configuration |
|---|---|
| 2014-2018 | Chevrolet Silverado 1500; select LV3 4.3L V6, L83 5.3L V8 and L86 6.2L V8 configurations. Verify VIN and original accessory drive. |
| 2019 | Chevrolet Silverado 1500; previous-generation applications only where GM catalogs this balancer. Do not assume compatibility with the redesigned 2019 truck. |
| 2014-2018 | GMC Sierra 1500; select LV3 4.3L V6, L83 5.3L V8 and L86 6.2L V8 configurations. Verify VIN and original accessory drive. |
| 2019 | GMC Sierra 1500 Limited; applicable previous-generation engine and accessory-drive configurations only. |
| 2015-2020 | Chevrolet Tahoe; select 5.3L L83 V8 or 6.2L L86 V8 applications as equipped. Verify engine and VIN. |
| 2015-2020 | Chevrolet Suburban; select 5.3L L83 V8 or 6.2L L86 V8 applications as equipped. Verify engine and VIN. |
| 2015-2020 | GMC Yukon and Yukon XL; select 5.3L L83 V8 and 6.2L L86 V8 configurations. Verify VIN and original drive system. |
| 2015-2020 | Cadillac Escalade and Escalade ESV; select 6.2L L86 V8 configurations. Verify VIN and original drive system. |
| 2018 | Chevrolet Express 2500 and Express 3500; select 4.3L LV3 V6 applications. Verify VIN and accessory drive. |
| 2018 | GMC Savana 2500 and Savana 3500; select 4.3L LV3 V6 applications. Verify VIN and accessory drive. |
The application chart identifies cataloged vehicle families and engine configurations, not unrestricted fitment for every vehicle within the stated years. Confirm the VIN and engine RPO with the GM parts catalog. In particular, 2019 Silverado applications require model-generation verification. Do not assume compatibility with eAssist configurations, later L84/L87 engines, or modified accessory drives unless specifically confirmed by GM.
- One new genuine GM crankshaft harmonic balancer assembly, part number 12684590
Crankshaft center bolt and washer are not included.
This GM Genuine Parts balancer mounts at the front of the crankshaft. Its function is to damp crankshaft torsional vibration while providing the specified pulley arrangement for the engine's serpentine accessory drive.
GM catalogs an outside diameter of 7.8 inches, an inside diameter of 1.5 inches and a depth of 1.1 inches. The depth is retained under its catalog designation and is not represented as a verified overall front-to-back assembly measurement. The 13-groove entry refers to the cataloged total pulley groove quantity; it does not establish a single 13-rib replacement belt.
GM part number 12684590 supersedes earlier GM numbers 12620312 and 12662037 in applicable catalog records. A superseded number alone does not verify fitment for an engine swap or altered drive arrangement.
The center bolt and washer are not included. The catalog identifies a 16 mm coarse-thread center bolt and a 103 mm bolt length, but the correct service fastener and installation procedure must be determined for the exact application.
Use the applicable GM vehicle service procedure and appropriate harmonic balancer removal and installation tools. Inspect the crankshaft interface, mounting surfaces, keyway alignment and existing pulley configuration before installation.
Obtain the correct crankshaft bolt and washer separately as required. Follow the vehicle-specific instructions for balancer seating, fastener replacement and tightening. Do not substitute torque values from a different engine or assume that previously installed hardware is reusable.
After installation, inspect pulley alignment, belt routing and surrounding clearances. Verify correct accessory-drive operation before returning the vehicle to service.
Which Chevrolet Silverado and GMC Sierra models use this balancer?
Cataloged applications include select 2014-2018 Silverado 1500 and Sierra 1500 configurations, plus applicable 2019 previous-generation Silverado and Sierra 1500 Limited configurations. Verify the VIN, engine RPO and original drive system before ordering.
Does GM 12684590 fit Tahoe, Suburban, Yukon and Escalade SUVs?
It is cataloged for select 2015-2020 Tahoe, Suburban, Yukon, Yukon XL, Escalade and Escalade ESV applications equipped with the applicable original engine and accessory-drive configuration. Confirm exact fitment by VIN.
Does this harmonic balancer include the crankshaft bolt and washer?
No. The crankshaft center bolt and washer are not included. Use the correct service hardware for the vehicle.
What are the dimensions of GM harmonic balancer 12684590?
The cataloged outside diameter is 7.8 inches (198 mm), inside diameter is 1.5 inches (38 mm), and depth is 1.1 inches (28 mm). These dimensions alone do not verify fitment.
Does part number 12684590 replace GM 12620312 and 12662037?
Yes. Both are listed as previous GM part numbers. Verify the original vehicle application and installed accessory-drive configuration before using the replacement part.
