Water Pump Kit with Cover and Seals, Duramax | 2001-2005

The Merchant Automotive Water Pump Kit includes everything you need to replace the water pump on 2001-2005 Chevy Silverado and GMC Sierra 2500HD and 3500HD trucks with the LB7 and LLY 6.6L Duramax diesel. It includes a new Gates water pump with cover, new water pump studs, all of the seals and gaskets for the job, and a Flywheel Lock so you can remove the harmonic balancer without pulling the starter.

Note: The crankshaft balancer bolt must be removed to replace the water pump. The factory bolt is a one-time-use bolt and must be replaced. It is not included in this kit. Order the Crankshaft Balancer Bolt with your kit.

Features

• New OEM-style Gates water pump with cover, a direct replacement that restores factory-like function
• All necessary seals and gaskets included
• Two new OEM-style water pump studs
• Includes a Lisle flywheel lock to hold the engine while removing the balancer bolt
• All-in-one kit built for a complete Duramax water pump job

What's Included

• (1) Water pump with cover
• (1) Water pump to engine cover seal
• (1) Bypass pipe seal
• (1) Upper bypass pipe seal
• (1) Water pump outlet gasket
• (2) Water pump studs
• (1) Flywheel Lock

Why Replace It

Water pumps are a common wear item on every vehicle, including the Duramax. The water pump keeps coolant moving through the engine. As a Duramax ages, the factory water pump wears out, and skipping coolant flushes at the recommended intervals can cause it to fail early. A failing water pump can lead to overheating and serious engine damage if it is not replaced in time.

Signs of a Failing Water Pump

Most water pumps show symptoms before they fail completely. Watch for:

• Coolant leaking from the weep hole, a small hole in the pump designed to show when the seal is failing
• Rust or deposit buildup on the impeller in more advanced cases
• A loose water pump pulley or a whining noise from the pump, which is less common
• Engine overheating. The water pump is one of several things to check when diagnosing an overheating truck.

Installation Tips

• Install the flywheel lock through the inspection opening on the bottom of the transmission to hold the engine while you remove the balancer bolt.
• Replace the crankshaft balancer bolt. Do not reuse the old one.
• Clean all sealing surfaces before installing the new seals and gaskets.
• Flush the cooling system and fill with the correct coolant after the new pump is installed.

Related Parts

• Crankshaft Balancer Bolt

Frequently Asked Questions

Is the crankshaft balancer bolt included?
No. The balancer bolt is a one-time-use bolt and must be replaced. Order the Crankshaft Balancer Bolt separately.

Do I need to remove the starter to hold the engine?
Not on trucks with the Allison automatic. The included flywheel lock goes in through the inspection opening on the bottom of the transmission, so the starter can stay in place. The flywheel lock does not fit trucks with the ZF6 manual transmission.

Will this kit fit my 2006 or newer Duramax?
No. Use our 2006-2016 Water Pump Kit or our 2017-2025 Water Pump Kit.

Should I flush the coolant when I replace the water pump?
Yes. Old coolant is a common cause of early water pump failure. Flush the system and refill with fresh coolant.

For warranty information or to submit a claim, see our Warranty Form.