2021 GMC Sierra 3500 Cooling System Parts

This table covers the engine coolants and antifreeze formulations specified for this cooling system. Typical signs include a rising temperature gauge, rusty or sludged coolant, or a heater that blows cold. Use the chemistry named in the notes. Mixing silicate, OAT and HOAT formulas can gel in the radiator. Read more

17 Coolant / Antifreeze parts for the 2021 GMC Sierra 3500 come from 6 brands — PRESTONE, PEAK, VALVOLINE and 3 other brands. The "Popular" part is FVP MV5050GAL. 13 parts fit every engine; the other 4 are engine-specific.

In the Compatible With All Colors grade, PRESTONE supplies 1 part: grouped under the catalog's "Compatible With All Colors" designation — the notes column spells out what sets them apart. A representative part number is PRESTONE AF3055.

The Economy section lists 4 options from FVP, PEAK, PRESTONE and 1 other brand — the catalog's value-priced group. FVP MV5050GAL is listed in this group.

In the Heavy Duty grade, PRESTONE supplies 1 part: rated for severe service. A representative part number is PRESTONE AFC12100.

In the Premium grade, PRESTONE and PEAK supply 4 parts: a step above OE specification in materials, tolerances or warranty terms. A representative part number is PRESTONE AF2100.

In the Standard Replacement grade, VALVOLINE, PRESTONE, ACDELCO and 2 other brands supply 7 parts: built to original-equipment specification. A representative part number is ACDELCO 105027.

This table covers the Coolant Air Bleed Hose pipes. Read more

2 Coolant Air Bleed Hose / Pipe parts for the 2021 GMC Sierra 3500 come from GM GENUINE.

Part numbers include GM GENUINE 11549085 and GM GENUINE 85056532.

This table covers the hard pipes and extra hoses in the coolant circuit. Read more

5 Coolant Hose / Pipe parts for the 2021 GMC Sierra 3500 come from GM GENUINE. The "Popular" part is GM GENUINE 85119168.

Listed part numbers: GM GENUINE 85119168, GM GENUINE 85119158 and GM GENUINE 12737234, plus the other parts above.

This table covers the seals at the Coolant Hose / Pipe. Typical signs include a wet housing, a drip after sitting, or fluid flung off a rotating shaft. Fix the surface the seal rides on. A new seal on a grooved shaft will leak again. Read more

5 Coolant Hose / Pipe Seal parts are listed for the 2021 GMC Sierra 3500, from GM GENUINE, MAHLE / CLEVITE and AJUSA. GM GENUINE 12658352 carries the "Popular" badge.

Part numbers include GM GENUINE 12658352, AJUSA 16097400 and GM GENUINE 12737097, among others listed above.

This table covers the Coolant Hose retainers and clips. Read more

3 Coolant Hose Retainer / Clip parts for the 2021 GMC Sierra 3500 come from GM GENUINE.

This group includes GM GENUINE 11548857, GM GENUINE 11547354 and GM GENUINE 11547355.

This table covers the overflow / expansion tanks that hold extra coolant. Read more

One part is listed for the 2021 GMC Sierra 3500 — GM GENUINE 85639732.

This table covers the caps on the overflow / expansion tank. Typical signs include a leak at the neck, a cap that will not hold pressure, or a missing tether. Match the pressure rating or thread in the notes — radiator, reservoir and fuel caps are not interchangeable. Read more

6 Coolant Reservoir Cap parts are listed for the 2021 GMC Sierra 3500, from MOTORAD, DORMAN, SKP and 2 other brands. DORMAN 54218 carries the "Popular" badge.

Part numbers include DORMAN 54218, SKP SK54218 and CALORSTAT RC0144, among others listed above.

This table covers the adapters used to pressure-test this cooling system. Read more

2 Cooling System Tester Adapter parts for the 2021 GMC Sierra 3500 come from MOTORAD.

This group includes MOTORAD 3128 and MOTORAD 3127.

This table covers the Hose clamps. Read more

5 Hose Clamp parts for the 2021 GMC Sierra 3500 come from GM GENUINE. The "Popular" part is GM GENUINE 11570871.

Listed part numbers: GM GENUINE 11570871, GM GENUINE 11549085 and GM GENUINE 11549298, plus the other parts above.

This table covers the intercoolers that cool turbo or supercharger charge air. Read more

4 Intercooler parts for the 2021 GMC Sierra 3500 come from 4 brands — TECHPRO, GM GENUINE, TYC and 1 other brand.

The Economy section: 1 option from TECHPRO. TECHPRO GM3012129 is listed in this group.

Standard Replacement: 1 part, from GM GENUINE. A representative part number is GM GENUINE 84747171.

2 further parts sit outside the graded sections, with the same engine-level match.

Part numbers include TECHPRO GM3012129, GM GENUINE 84747171 and TYC 18145, among others listed above.

This table covers the Intercooler Air Hose pipes. Read more

3 Intercooler Air Hose / Pipe parts for the 2021 GMC Sierra 3500 come from 3 brands — DORMAN, GM GENUINE and SKP.

Part numbers include DORMAN 667828, GM GENUINE 84870726 and SKP SK84870726.

This table covers the radiators that dump engine heat to airflow through the core. Typical signs include overheating in traffic, a wet core, or coolant that disappears with no puddle. Replace the cap if it cannot hold the rated pressure, and bleed the system after the swap. Read more

10 Radiator parts for the 2021 GMC Sierra 3500 come from 7 brands — GPD, CSF, GM GENUINE and 4 other brands. The "Popular" part is CSF 3938.

The Economy section: 2 options from GPD. GPD 13893C is listed in this group.

Standard Replacement: 8 parts, from CSF, GM GENUINE, ACDELCO and 3 other brands. A representative part number is CSF 3938.

This table covers the caps that hold system pressure at the radiator or reservoir neck. Typical signs include a leak at the neck, a cap that will not hold pressure, or a missing tether. Match the pressure rating or thread in the notes — radiator, reservoir and fuel caps are not interchangeable. Read more

2 Radiator Cap parts for the 2021 GMC Sierra 3500 come from 2 brands — ACDELCO and PROFESSIONAL PARTS SWEDEN.

Listed part numbers: ACDELCO RC124 and PROFESSIONAL PARTS SWEDEN 21342353.

This table covers the petcocks used to drain the radiator. Read more

One part is listed for the 2021 GMC Sierra 3500 — GM GENUINE 22790134.

This table covers the Radiator Fan blades. Typical signs include chatter, streaks, or a skip at the top of the stroke. Confirm left and right lengths in the notes — they are often different. Read more

One part is listed for the 2021 GMC Sierra 3500 — GM GENUINE 1582003.

This table covers the Radiator Fan clutches. Typical signs include slip at highway speed, chatter on takeoff, or a pedal that stays low. Resurface or replace the flywheel with the clutch — a heat-checked flywheel wastes the new disc. Read more

This group shows a single part: GM GENUINE 85824793.

This table covers the Radiator Fan pulleys. Typical signs include a growl or chirp that follows engine speed, or a pulley that will not spin freely by hand. Spin each pulley with the belt off. Roughness or play means replace it with the belt. Read more

2 Radiator Fan Pulley parts for the 2021 GMC Sierra 3500 come from GM GENUINE.

This group includes GM GENUINE 12714130 and GM GENUINE 12714129.

This table covers the shrouds that duct air through the fan and radiator. Read more

This group shows a single part: GM GENUINE 87868034.

This table covers the upper, lower and connecting hoses between radiator, engine and reservoir. Typical signs include swelling, cracks, a soft spot, or a leak at a clamp. Replace adjacent aged hoses while the system is drained — they share the same heat cycle. Read more

2 Radiator Hose parts are listed for the 2021 GMC Sierra 3500, from ACDELCO and GM GENUINE.

Part numbers include ACDELCO 85122989 and GM GENUINE 85056546.

This table covers the senders that report coolant temperature to the gauge or ECU. Typical signs include a gauge that sits on empty or overheat, or a lamp that does not match what the engine is doing. Rule out the cluster and the wiring before replacing the sender. Read more

8 Temperature Sender / Sensor parts for the 2021 GMC Sierra 3500 come from 8 brands — ULTRA-POWER, GPD, HOLSTEIN and 5 other brands. The "Popular" part is ULTRA-POWER 5S13427.

The Economy section: 3 options from ULTRA-POWER, GPD and HOLSTEIN. ULTRA-POWER 5S13427 is listed in this group.

Standard Replacement: 5 parts, from STANDARD MOTOR PRODUCTS, FACET, GM GENUINE and 2 other brands. A representative part number is STANDARD MOTOR PRODUCTS TX247.

Listed part numbers: ULTRA-POWER 5S13427, GPD 1712496 and HOLSTEIN 2CTS0184, plus the other parts above.

This table covers the thermostats that open the coolant circuit at the specified temperature. Typical signs include slow warm-up, a gauge that climbs in traffic, or heat that never quite arrives. Replace the housing gasket with the thermostat and bleed the system so a trapped air pocket does not cook the new part. Read more

10 Thermostat parts are listed for the 2021 GMC Sierra 3500, from MOTORAD, CALORSTAT, GM GENUINE and 2 other brands. MOTORAD 447185 carries the "Popular" badge.

Economy: 1 part, from SKP. A representative part number is SKP SK131160.

The Standard Replacement section: 9 options from MOTORAD, CALORSTAT, GM GENUINE and 1 other brand. MOTORAD 447185 is listed in this group.

This table covers the seals at the thermostat housing and water outlet. Typical signs include a wet housing, a drip after sitting, or fluid flung off a rotating shaft. Fix the surface the seal rides on. A new seal on a grooved shaft will leak again. Read more

4 Thermostat / Thermostat Housing / Water Outlet Seal parts for the 2021 GMC Sierra 3500 come from 2 brands — GM GENUINE and MAHLE / CLEVITE.

Part numbers include GM GENUINE 12643149, GM GENUINE 94034146 and GM GENUINE 12680544, among others listed above.

This table covers the housings and outlets the thermostat sits in. Read more

5 Thermostat Housing / Water Outlet parts are listed for the 2021 GMC Sierra 3500, from GM GENUINE, MOTORAD and FOUR SEASONS. FOUR SEASONS 85945 carries the "Popular" badge.

Listed part numbers: FOUR SEASONS 85945, GM GENUINE 12706111 and GM GENUINE 12743523, plus the other parts above.

This table covers the gaskets that seal the Water Inlet. Typical signs include seepage at the joint, a burnt-oil smell, or a leak that appears only after a long drive. Clean both flanges and torque in the sequence the notes or the manual call for. Read more

This group shows a single part: GM GENUINE 12587397.

This table covers the pumps that circulate coolant through the block and radiator. Typical signs include coolant at the weep hole, pulley play, or a growl from the front of the engine. Replace the thermostat and refill with the specified coolant whenever the pump comes off. Read more

5 Water Pump parts are listed for the 2021 GMC Sierra 3500, from GMB, GM GENUINE, ACDELCO and 1 other brand. GM GENUINE 251817 carries the "Popular" badge.

This group includes GM GENUINE 251817, ACDELCO 2521039 and GATES 42229 and the remaining parts above.

This table covers the gaskets between the water pump and the block or housing. Typical signs include seepage at the joint, a burnt-oil smell, or a leak that appears only after a long drive. Clean both flanges and torque in the sequence the notes or the manual call for. Read more

This group shows a single part: MAHLE / CLEVITE GS34037.

This table covers the Water Pump Inlet tubes. Read more

One part is listed for the 2021 GMC Sierra 3500 — GATES HHA161.

This table covers the Water Pump Seal O-rings. Typical signs include a seep at a fitting or a housing that weeps after a service. Lube the new O-ring with the fluid it will see, and do not roll it into the groove. Read more

GM GENUINE supplies both parts for the 2021 GMC Sierra 3500.

Part numbers include GM GENUINE 12643779 and GM GENUINE 2512031.