XDP XD665 X-TRA Cool Water Pump - 2001-2005 LB7 / LLY Duramax

The XD665 XDP X-TRA Cool Water Pump is an OE-style direct-fit replacement water pump for the GM 6.6L LB7 and LLY Duramax - pump only, housing not included. It ships with a new seal set and carries a 2-year / unlimited mileage warranty. One critical install note before you order: the harmonic balancer bolt must be removed to replace the pump, and that bolt is a torque-to-yield fastener used only once - a new bolt is required for reassembly.

Pump Only - What That Means for Your Order

The XD665 replaces the water pump assembly and includes new seals for a direct-fit installation on the LB7 and LLY Duramax. The housing is not included. If you need the housing as well, plan to source it separately or consider a complete kit that bundles both components.

For owners who already have a serviceable housing and need only the pump and seals, this is the correct part to order. The 2-year / unlimited mileage warranty backs the pump itself. Confirm your housing situation before adding to cart.

The Harmonic Balancer Bolt Cannot Be Reused

The harmonic balancer bolt must be removed to access and replace the water pump on this platform. That bolt is a torque-to-yield fastener - it is a one-time-use part and must be replaced, not reinstalled. Have a new harmonic balancer bolt on hand before beginning the job. This is the single most commonly overlooked detail on this water pump service.

XD665 Specs

Confirm the specs match your application before ordering:

If your LB7 or LLY Duramax matches the fitment above and you need the pump only, this is the correct part to order.

Avoid These Common Mistakes

• Not having a replacement harmonic balancer bolt on hand. The factory TTY bolt is single-use and cannot be reinstalled. Source a new one before starting the job.
• Expecting the housing to be included. The XD665 is pump and seals only. If the housing is also needed, plan accordingly before ordering.
• Ordering for a 2006 or newer Duramax. The XD665 is confirmed for 2001-2005 LB7 and LLY applications. Verify your engine code before ordering if your build year is outside that range.

LB7 / LLY Duramax Fitment Coverage

The XD665 fits the following 2001-2005 GM Duramax applications:

• 2001-2004 Chevy Silverado 2500HD / 3500HD - 6.6L LB7 Duramax
• 2001-2004 GMC Sierra 2500HD / 3500HD - 6.6L LB7 Duramax
• 2004.5-2005 Chevy Silverado 2500HD / 3500HD - 6.6L LLY Duramax
• 2004.5-2005 GMC Sierra 2500HD / 3500HD - 6.6L LLY Duramax

Before You Order - Final Checklist

• Truck is a 2001-2005 GM 6.6L LB7 or LLY Duramax confirmed
• Pump only - housing sourced separately if needed
• Replacement harmonic balancer bolt on hand - factory TTY bolt is single-use
• New seal set confirmed included - no separate seal purchase required

For a 2001-2005 LB7 or LLY Duramax water pump replacement where the housing is already serviceable, the XD665 is the correct direct-fit pump to order.

Frequently Asked Questions