On the K2XX Silverado 1500 the water pump itself is easy \u2014 it is a handful of M8 bolts into the front cover with a reusable-style gasket. The time goes into access: draining 12-14 quarts of Dex-Cool, pulling the fan shroud and engine-driven fan clutch, and getting the serpentine belt off with a long tensioner tool. All three Gen V engines (4.3 LV3, 5.3 L83, 6.2 L86) use the same basic pump layout, so the procedure barely changes between them.
The two things people get wrong are torque and air. These bolts thread into aluminum and only want about 22 ft-lb; run them down with an impact and you will be chasing stripped threads. And if you just dump coolant in and drive off, the system traps air, the gauge swings, and you get a false overheat \u2014 use a spill-free funnel, run it up to temp with the heater on high, and let it burp properly. While you are in there, a new thermostat is a few dollars and saves a repeat teardown.
| Item | Type | |
|---|---|---|
| Floor jack 2 ton minimum Lift the front of the truck for coolant draining and lower hose access. | Required | shop |
| Jack stands 3 ton pair Support the truck while you work underneath. | Safety | shop |
| Drain pan 4 gallon / 16 qt low profile Catch the roughly 12-14 quarts of Dex-Cool. | Required | shop |
| Socket set, 3/8 in drive 8, 10, 13, 15, 18 mm 6-point Fan shroud, pulley, pump, hose clamp and bracket fasteners. | Required | shop |
| Ratchet and extensions 3/8 in drive, 3 in and 6 in extensions, swivel Reach the lower pump bolts past the pulley and frame rail. | Required | shop |
| Serpentine belt tool Long-handle tensioner tool or 1/2 in breaker bar with 15 mm socket Rotate the automatic belt tensioner to release the accessory belt. | Required | shop |
| Fan clutch wrench 36 mm (some builds use four 13 mm bolts to the pulley) Loosen the fan clutch nut off the water pump hub; not all trucks use a nut. | Required | shop |
| Pulley holding tool Water pump pulley holder or strap wrench Keeps the pulley from spinning while breaking the fan clutch loose. | Recommended | shop |
| Hose clamp pliers Flat-band spring clamp pliers, cable type preferred GM factory spring clamps on the upper/lower radiator and heater hoses. | Required | shop |
| Torx bit set T15-T30, with T20 and T25 Some air deflector, shroud and coolant recovery tank screws are Torx. | Recommended | shop |
| Pick and scraper set Plastic/brass gasket scraper Clean the front cover sealing surface without gouging the aluminum. | Required | shop |
| Torque wrench 3/8 in drive, 5-75 ft-lb Water pump bolts go into aluminum and must be torqued, not guessed. | Required | shop |
| Torque wrench, 1/2 in drive 25-150 ft-lb Fan clutch nut and belt tensioner bolt if removed. | Recommended | shop |
| Coolant funnel kit Spill-free funnel with GM/universal adapters Fill and burp the system without airlocks. | Required | shop |
| Shop light LED work light The lower pump bolts and hose connections are in shadow. | Recommended | shop |
| Water pump Gen V LT/EcoTec3 pump with gasket (4.3/5.3/6.2 share design) The replacement unit; get one with the pulley if yours is press-fit. | Parts | shop |
| Thermostat and housing gasket Engine coolant thermostat, Gen V Cheap to do while the pump area is open and it is a common secondary leak. | Parts | shop |
| Dex-Cool coolant GM Dex-Cool orange, 50/50 premix, 3-4 gallons Refill; never mix with green or yellow coolant. | Consumables | shop |
| Distilled water 1-2 gallons For mixing concentrate or topping off. | Consumables | shop |
| Serpentine belt Engine-specific accessory drive belt Replace if cracked or glazed while it is off. | Parts | shop |
| Brake/parts cleaner Non-chlorinated aerosol Clean the sealing face and old coolant residue. | Consumables | shop |
| Nitrile gloves and eye protection Coolant is toxic and hot coolant will scald. | Safety | shop |
Tool sizes are essentially identical across the 4.3, 5.3 and 6.2 in this generation: 13 mm M8 pump bolts, 15 mm belt tensioner, 8/10 mm shroud hardware. The 4.3 V6 has a shorter front accessory layout so belt routing differs and there is slightly more room at the pump. Belt length and the specific pump part number differ by engine, and 6.2 trucks with heavy-duty cooling may have extra shroud/hose brackets to unbolt.
| Water pump to front cover bolts (M8) | 22 ft-lb (30 Nm) |
| Thermostat housing / coolant inlet bolts | 18 ft-lb (25 Nm) - verify in the service manual |
| Water pump pulley bolts (if bolt-on) | verify in the service manual |
| Fan clutch nut to pump hub | verify in the service manual |
| Belt tensioner bolt | 37 ft-lb (50 Nm) - verify in the service manual |
| Fan shroud bolts | Hand tight, about 7 ft-lb (10 Nm) |
Bolt sizes here (13 mm M8 pump bolts, 15 mm tensioner, 8/10 mm shroud) and the 22 ft-lb pump torque apply to all Gen V EcoTec3 engines in this generation, but fan clutch retention (large nut versus four bolts) and the pulley bolt torque vary by build date, so check your truck before ordering a 36 mm wrench and verify the fan clutch and pulley torques in a GM service manual.
Roughly 12-14 quarts (about 3 to 3.5 gallons) of Dex-Cool 50/50 depending on engine and cooling package. Buy four gallons of premix so you have enough to fill, burp and top off over the next few days.
22 ft-lb (30 Nm) for the M8 pump-to-front-cover bolts, tightened evenly in a criss-cross pattern. They thread into aluminum, so use a torque wrench rather than an impact gun.
The radiator can stay in. You do need to remove the fan shroud and the engine-driven fan clutch to get the pulley and pump out, which means either a 36 mm fan clutch wrench or removing four bolts through the pulley depending on your build.
Yes. The thermostat housing mounts at the pump/coolant inlet and it is already coming loose, so a new thermostat and gasket is cheap insurance against a second coolant drain a year later.