WEHRLI CUSTOM FAB WCF100155 1999-2023 GM DURAMAX BILLET COOLANT HEATER CORE FIREWALL FITTING

Product Description

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The WEHRLI CUSTOM FAB WCF100155 GM DURAMAX BILLET COOLANT HEATER CORE FIREWALL FITTING is a precision-machined upgrade designed to replace the weak factory plastic heater core firewall fitting found on many Duramax trucks. The OEM connector can become brittle over time due to heat cycles and coolant exposure, often leading to leaks or sudden failure that can leave your truck stranded.

This billet aluminum fitting from Wehrli Custom Fab provides a durable, long-term solution by replacing the factory plastic piece with a high-strength CNC-machined aluminum component. Designed for direct replacement installation, the WCF100155 ensures a secure connection between the heater core and coolant system while improving reliability for both stock and performance-built Duramax engines.

Whether you’re performing routine maintenance, replacing a broken connector, or upgrading weak cooling system components while working on your engine bay, this billet firewall fitting provides peace of mind and professional-grade durability.

Key Benefits:

• Direct replacement for fragile OEM plastic heater core firewall fitting
• CNC-machined billet aluminum construction for superior durability
• Improves reliability of the Duramax cooling system
• Helps prevent coolant leaks caused by brittle factory fittings
• Perfect upgrade during coolant system maintenance or engine work
• Clean billet appearance for a refined engine bay
• Made in the USA

Fitment:

• 1999 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax
• 2000 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax
• 2001 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LB7
• 2002 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LB7
• 2003 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LB7
• 2004 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LB7 / LLY
• 2005 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LLY
• 2006 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LBZ
• 2007 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LBZ / LMM
• 2008 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LMM
• 2009 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LMM
• 2010 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LMM
• 2011 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LML
• 2012 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LML
• 2013 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LML
• 2014 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LML
• 2015 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LML
• 2016 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax LML
• 2017 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P
• 2018 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P
• 2019 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P
• 2020 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P
• 2021 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P
• 2022 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P
• 2023 Chevrolet Silverado / GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P

FAQ

Why should I replace the factory heater core firewall fitting?

The OEM plastic fitting can become brittle over time due to heat cycles and coolant exposure. When it fails it can cause sudden coolant leaks. The billet WCFab replacement provides a much stronger and more reliable connection.

Is this a direct replacement part?

Yes. The WCF100155 is designed as a direct replacement for the factory heater core firewall connector and installs using the existing hose routing.

Does this fitting improve cooling performance?

While the primary purpose is durability and leak prevention, replacing the factory plastic connector with a billet fitting ensures a stronger and more secure coolant connection.

Is this compatible with all Duramax engines?

Yes. This fitting is designed for GM Duramax trucks from 1999 through 2023 including LB7, LLY, LBZ, LMM, LML, and L5P engines.