Performance Water Pump Kit for Hummer H3,H3T (2008-2010) 5.3L

Heavy-Duty Performance Water Pump Kit for 2008-2010 Hummer H3,H3T (GMT345)

What it Does: The Performance Water Pump Kit replaces the leak-prone factory cooling pump on the 2008-2010 Hummer H3,H3T to restore pressurized coolant circulation and prevent catastrophic engine overheating under heavy loads.

The Stock Hummer H3,H3T Cooling System Vulnerability

Factory cooling systems on the GMT345 platform powered by the LH8 5.3L V8 suffer premature shaft seal failure and bearing degradation due to severe thermal cycling and high engine bay heat soak. Over time, the stock mechanical seal hardens, causing coolant to weep through the drainage cavity and depressurize the system. Furthermore, factory stamped impellers can experience fluid cavitation at elevated RPM, leading to localized hotspotting, vapor pocket formation, and warped cylinder head surfaces during sustained trail crawling or heavy towing.

The Engineering Solution

This direct-fit water pump assembly upgrades system reliability with a reinforced cast housing and heavy-duty, unitized dual-row bearings that withstand extreme radial serpentine belt loads. Fitted with an upgraded carbon-ceramic mechanical shaft seal, it eliminates weeping and holds dynamic cooling pressure reliably. The balanced internal impeller is engineered to prevent cavitation, ensuring uniform flow rates through the engine block and radiator cores. It includes a calibrated thermostat housing assembly, replacement hardware, and OEM-spec gaskets for an airtight, leak-free seal.

What's Included

• 1 Engine Water Pump
• 1 Thermostat Housing
• 1 Thermostat
• 2 Rectangular Gaskets
• 1 Oval Gasket
• 2 Mounting Bolts

Technical Specifications

Compatibility

• 2008-2010 Hummer H3 5.3L V8
• 2009-2010 Hummer H3T 5.3L V8

Frequently Asked Questions & Fitment Warnings

Does this fit the GMT345 H3,H3T?

Yes, this is a direct fit for the 2008-2010 Hummer H3,H3T equipped with the LH8 5.3L V8 engine. Does not fit 3.5L (L52) or 3.7L (LLR) inline-5 engine configurations.

Do I need to bleed the cooling system after installation?

Yes, always perform a complete cooling system vacuum bleed or air purge to remove trapped air pockets and torque mounting bolts to factory specifications.

The Hummer Caliber

The Hummer GMT345 chassis requires unwavering cooling stability for harsh off-road trails and rigorous towing. Installing an upgraded water pump and thermostat kit safeguards your powertrain against thermal degradation, ensuring dependable heat management across demanding environments.