Alliant Power Water Pump with cast iron impeller
Fits 2006-2016 Chevrolet and GMC vehicles with 6.6L Duramax Diesel
The Alliant Power AP63563 Water Pump for 2006–2016 Chevy/GMC 6.6L Duramax engines is an OEM‑quality, brand‑new (not reman) pump engineered to restore and enhance your cooling system’s performance. Featuring a durable cast impeller, precise housing, and included mounting gaskets, this pump is built to handle heavy towing, performance tuning, and harsh work environments while maintaining consistent coolant flow and stable operating temperatures. Backed by Alliant Power’s industry‑leading technical support and a 100,000‑mile warranty, the AP63563 is a dependable upgrade or replacement for failing factory water pumps on LBZ, LMM, and LML Duramax applications.
This AP63563 water pump is a direct‑fit replacement for a wide range of GM 6.6L Duramax platforms, making it ideal for fleets, work trucks, and enthusiast builds.
2006–2016 GM 6.6L Duramax diesel engines (Chevy Silverado HD / GMC Sierra HD).
Common applications include LBZ, LMM, and LML Duramax configurations in 2500HD and 3500HD trucks used for towing, hauling, and commercial duty.
Designed as an OE‑style replacement for original GM/Isuzu Duramax pumps, ensuring proper belt alignment, pulley spacing, and coolant passage geometry.
This pump replaces the following original part numbers, making it easy to confirm compatibility during repairs or cross‑referencing:
GM 98031233 and 12637105
AC Delco 251‑748 (often listed as 251-7380 / 251-7382 by some catalogs)
Alliant Power cross‑references: AP63563, APP1508, AP63563, DA2251174, AP63563, DA2251296
DMAXStore DMAXWATERKIT-0616
If your OE water pump matches any of these references, the AP63563 is designed to be a direct replacement.
Duramax owners depend on consistent cooling performance whether towing, commuting, or running performance tunes, and this pump is built around those needs.
Reliable cooling under heavy payloads and trailer loads minimizes downtime and protects expensive engine and aftertreatment components.
Direct OE‑style fit means quick turnaround in shop environments, improving fleet uptime and reducing labor costs on repeated jobs.
Long service life helps fleet managers plan maintenance intervals more confidently.
Stable coolant flow helps prevent temperature spikes during long grades, hot ambient conditions, or high‑power tuning, which is critical for head gasket and turbocharger longevity.
Quality bearings and seals reduce the likelihood of sudden catastrophic failures that could leave a truck stranded while towing.
Direct‑fit design retains stock belt routing and accessory alignment, so it plays nicely with aftermarket radiators, thermostats, and cooling upgrades.
A worn or failing water pump on a 6.6L Duramax can trigger multiple drivability issues and, in some cases, diagnostic trouble codes when overheating occurs.
Coolant leaks: Visible coolant dripping from the front, drivers side of the engine, especially around the water pump weep hole or gasket area.
Overheating: Rising coolant temperature gauge, especially at idle, under load, or while towing, can indicate reduced flow or internal pump failure.
Whining or grinding noises: Bearing wear can create abnormal noises at the front of the engine that rise with RPM.
Steam or sweet smell: Steam from under the hood or a sweet odor can indicate a coolant leak from the pump or nearby connections.
Low coolant level: Repeatedly needing to top off the coolant with no obvious hose leak often points to pump housing or seal seepage.
While the water pump itself does not have an electrical connection, a failing pump can contribute to overheating conditions that trigger related DTCs:
P0128 – Coolant Temperature Below Thermostat Regulating Temperature (can appear if coolant flow is poor or thermostat and pump performance are compromised).
P0217 – Engine Overtemp Condition (can set if the engine overheats due to insufficient coolant circulation).
In severe overheating, additional codes related to reduced power or derate strategies may appear as the ECM attempts to protect the engine.
When any of these symptoms or codes appear, replacing the water pump with a quality unit like the AP63563 is a key step in restoring reliable operation.
Alliant Power backs the AP63563 water pump with robust mileage‑based coverage, underscoring its confidence in durability and quality.
Warranty coverage: 2 Year / 100,000 miles
For the most accurate and current warranty terms, customers should review Alliant Power’s warranty information online or through official documentation at the time of purchase.
A: This pump is designed for 2006–2016 GM 6.6L Duramax diesel applications and directly replaces OE part numbers 98031233, 251‑738, and 12637105. If your truck is a 6.6L Duramax in that year range and your factory pump crosses to one of these numbers, the AP63563 is engineered as a direct fit.
A: The AP63563 listed here is a brand‑new water pump, not a remanufactured unit. Alliant Power builds this pump to meet or exceed OE specs using new castings, impeller, and bearings for long service life.
A: Yes, the pump includes the necessary mounting gaskets needed for installation, as noted in multiple distributor listings. Reusing old gaskets is not recommended, so having new gaskets included helps ensure a proper seal and leak‑free installation.
A: Installation generally requires standard mechanic’s tools plus whatever is needed to remove the fan, belt, and front‑end accessories typical of a Duramax water pump job. Many technicians also use a fan clutch removal tool and a coolant drain pan, and it is strongly recommended to refill with fresh, correct‑spec coolant. You may also need a flywheel lock tool or equivalent to hold the crankshaft while removing the damper bolt.
A: Alliant Power lists this part as having coverage for 2 years or 100,000 miles, subject to the official terms and conditions on their vendor warranty page. Customers should review Alliant’s current warranty policy for specific time/mileage combinations, installation requirements, and any documentation needed for claims. https://parts.alliantpower.com/en-us/ap-warranty-policy
A: Replacing a worn or partially failed pump with the AP63563 can significantly improve coolant circulation, which is critical when towing or hauling heavy loads. While the pump alone cannot fix issues from clogged radiators or bad thermostats, it is a key component in a healthy cooling system and helps reduce overheating risk under load.
A: Yes, the pump is designed as an OE‑style replacement, so it works with stock and moderately tuned engines as long as they retain the factory accessory and belt layout. For extreme builds with significantly higher‑than‑stock power, it is still commonly used, but overall cooling system condition (radiator, fan clutch, thermostat) must also be considered.
A: Indirectly, yes—by helping maintain the correct engine operating temperature, the water pump supports efficient combustion and stable engine management. Any fuel economy gains are usually modest and tied to restoring proper cooling rather than adding power, but a properly functioning cooling system is essential for consistent mileage.
A: The pump itself is not electronically monitored, but overheating caused by poor coolant flow can trigger codes like P0128 or P0217 and may illuminate the check engine light. If those codes appear along with overheating or coolant loss, inspection of the water pump, thermostat, and cooling system is strongly recommended.
A: Alliant Power is widely regarded as a leading diesel parts provider in the U.S., supplying components for light‑, medium‑, and heavy‑duty vehicles and equipment. Their emphasis on quality, OE‑level specs, and strong technical support has made them a go‑to brand for many professional diesel shops and fleet operators.
When you are ready to restore your Duramax’s cooling system with a high‑quality, direct‑fit solution, the Alliant Power AP63563 Water Pump from NorCal Diesel Performance delivers the durability, reliability, and coverage your truck deserves.
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