12639701 Diesel Glow Plugs 9G for Duramax 6.6L - Reliable Cold Starts

In this review the 12639701 Diesel Glow Plugs 9G are examined for owners of GM 6.6L Duramax trucks from 2006 to 2016 who need a cost-effective replacement set that restores cold-starting and combustion stability. The reviewer found these glow plugs to be a straightforward, highquality aftermarket alternative that fits LBZ, LGH, LLY, LML and LMM engines and ships as an 8-piece kit; the single biggest reason to buy is the proper fit and function on compatible Chevy and GMC heavyduty trucks, which can clear misfire or check engine light issues related to faulty preheat operation.

Key Features

• Compatibility: Direct fit for GM 6.6L V8 Duramax engines used in many Chevy and GMC 2500/3500 models from 2006 to 2016, reducing the risk of ordering the wrong part.
• Preheat function: Designed to preheat combustion chambers so diesel engines start faster in cold conditions and maintain reliable ignition across cylinders.
• Self-regulating design: Controls electrical flow as temperatures rise to prevent overheating and protect the plug and wiring during operation.
• Durable construction: Manufactured to exceed original equipment performance standards for form and fit to provide a long service life when installed correctly.
• Complete kit: Includes eight 12639701 glow plugs so the typical installation for most cylinders is covered in one purchase.

Who It's For

This product is best for owners of Chevy Silverado, GMC Sierra, Chevy Express and GMC Savana trucks equipped with the GM 6.6L Duramax engines (LBZ, LGH, LLY, LML, LMM) from model years 2006 through 2016 who want a like-for-like replacement to restore cold-start and driveability performance.

Drivers who are not comfortable with mechanical work should seek professional installation, since no installation instructions are included and customers reported mixed ease of installation; anyone who needs factory warranty parts or original equipment numbering should verify fitment carefully before purchase or provide a VIN for confirmation.

Pros & Cons

Pros

• Good fit and function on compatible Duramax engines, often resolving glowplugrelated check engine lights.
• Selfregulating design helps prevent overheating of the plug and electrical system during warmup.
• Comes as an 8piece pack, convenient for replacing multiple cylinders in one job.

Cons

• Installation can be fiddly; some customers reported issues with the wire nut connection and recommend careful handling or professional installation.
• Durability received mixed feedback in a few reports, including a breakage during removal, so care and correct tools are important.

Specifications

Part Number	12639701 (replaces 97364968)
Quantity	8 pieces per package
Engine Fit	GM 6.6L V8 Duramax (LBZ, LGH, LLY, LML, LMM)
Vehicle Fit	Chevy Silverado/Sierra/Express and GMC Sierra/Savana 2006-2016
Function	Diesel glow plug preheat for cold starts and cylinder ignition
Design	Self-regulating to control electrical flow and prevent overheating

Our Verdict

The 12639701 Diesel Glow Plugs 9G are a practical, valueoriented replacement for Duramax owners who need reliable preheat performance and proper fit for 2006-2016 Chevy and GMC 6.6L trucks. They deliver the core benefits of correct ignition and faster cold starts and come as an 8piece kit, but buyers should plan for careful installation or professional service due to some reported wiring and removal issues.

Frequently Asked Questions

Will these glow plugs fit my 2008 Chevy Silverado 2500?
Yes, these 9G glow plugs are listed as compatible with 2006-2016 Silverado 2500 HD models with the GM 6.6L Duramax engine; provide your VIN if you need exact confirmation.

How many plugs are included in the package?
The package contains eight 12639701 glow plugs, enough to replace most cylinder banks in one job.

Is professional installation required?
Professional installation is recommended because no instructions are included and customers have reported issues with wire nut tightening and occasional breakage during removal.