2026 GMC Sierra 2500 Engine Parts

This table covers the camshafts that open the valves. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12633925.

This table covers the Camshaft bearings. Typical signs include a growl that rises with speed, or play in the shaft or hub. Set preload the way the notes specify. A dry or crushed bearing fails quickly. Read more

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Listed part numbers: GM GENUINE 12631285 and GM GENUINE 12631286.

This table covers the bearings in the connecting-rod big ends. Typical signs include a growl that rises with speed, or play in the shaft or hub. Set preload the way the notes specify. A dry or crushed bearing fails quickly. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12685817.

This table covers the Crankcase pressure sensors. Typical signs include a check-engine light for MAP or fuel-rail pressure, or a limp mode under load. A vacuum leak or a clogged reference line will fake a bad pressure sensor. Read more

This group shows a single part: GM GENUINE 12814873.

This table covers the crankshafts that turn piston motion into rotation. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12677566.

This table covers the main bearings that support the crankshaft in the block. Typical signs include a growl that rises with speed, or play in the shaft or hub. Set preload the way the notes specify. A dry or crushed bearing fails quickly. Read more

This group shows a single part: GM GENUINE 12704537.

This table covers the Crankshaft Main Bearing caps. 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

This group shows a single part: GM GENUINE 12686745.

This table covers the Crankshaft Main Bearing Cap bolts. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 11610683.

This table covers the front and rear seals that keep oil in at the crankshaft. 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

2 Crankshaft Seal parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Part numbers include GM GENUINE 29606 and GM GENUINE 97209342.

This table covers the cylinder heads that close the top of the block. Read more

This group shows a single part: GM GENUINE 12716846.

This table covers the head gaskets that seal the block to the cylinder head. 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

GM GENUINE supplies the 4 Cylinder Head Gasket parts for the 2026 GMC Sierra 2500.

This group includes GM GENUINE 12747434, GM GENUINE 12747435 and GM GENUINE 12747436 and the remaining parts above.

This table covers the Engine Block drain plugs. Read more

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Listed part numbers: GM GENUINE 11588468 and GM GENUINE 94399639.

This table covers the block heaters that warm the coolant or oil in cold weather. Read more

This group shows a single part: GM GENUINE 12742345.

This table covers the Engine Cover retainers and clips. Read more

This group shows a single part: GM GENUINE 11588327.

This table covers the exhaust valves that let combustion gas out of the cylinder. Typical signs include a circuit that will not hold, a whistle, or a code for this valve. A stuck valve is often debris. Clean the ports before installing the new one. Read more

2 Exhaust Valve parts for the 2026 GMC Sierra 2500 come from 2 brands — GM GENUINE and QUALCAST.

Part numbers include GM GENUINE 12730002 and QUALCAST 10VKGMD66A5.

This table covers the crankshaft pulleys / harmonic balancers at the front of the engine. Read more

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Part numbers include GM GENUINE 12692644 and GM GENUINE 12723412.

This table covers the Harmonic Balancer bolts. Read more

2 Harmonic Balancer Bolt parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Part numbers include GM GENUINE 11589168 and GM GENUINE 97329601.

This table covers the Intake insulators. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 84262961.

This table covers the Intake manifolds. Typical signs include an exhaust tick, a vacuum leak, or a gasket that has burned through. Replace the gaskets and hardware; a warped flange will leak with a new gasket alone. Read more

3 Intake Manifold parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Listed part numbers: GM GENUINE 12715992, GM GENUINE 12716585 and GM GENUINE 12717925.

This table covers the Intake Manifold bolts. Read more

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Listed part numbers: GM GENUINE 11610472 and GM GENUINE 11588714.

This table covers the Intake Manifold covers. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 84262962.

This table covers the gaskets between the intake manifold and the cylinder head. 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

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12642410.

This table covers the mounts that hold the engine to the chassis. Typical signs include a clunk on takeoff, a vibration at idle, or a separated rubber insert. Support the powertrain before unbolting a mount, and torque the fasteners in the notes. Read more

2 Motor Mount parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Part numbers include GM GENUINE 84070092 and GM GENUINE 85043936.

This table covers the engine oils listed by grade and specification for this engine. Typical signs include a low-oil lamp, knocking after a long interval, or oil that has gone thin and black well before the next service. Match the viscosity and spec in the notes (and on the filler cap). The tables group grades — they are not interchangeable. Read more

13 Oil parts for the 2026 GMC Sierra 2500 come from 4 brands — VALVOLINE, LIQUI MOLY, ACDELCO and 1 other brand. The "Popular" part is VALVOLINE 774038.

The Conventional section lists 2 options from LIQUI MOLY — grouped under the catalog's "Conventional" designation — the notes column spells out what sets them apart. LIQUI MOLY 22038 is listed in this group.

The Full Synthetic section lists 2 options from VALVOLINE — full-synthetic oils. VALVOLINE 774038 is listed in this group.

The Heavy Duty / Diesel section lists 8 options from VALVOLINE, ACDELCO, MOBIL and 1 other brand — grouped under the catalog's "Heavy Duty / Diesel" designation — the notes column spells out what sets them apart. ACDELCO 109214 is listed in this group.

The Synthetic Blend section lists 1 option from VALVOLINE — synthetic-blend oils. VALVOLINE 891005 is listed in this group.

This table covers the heat exchangers that cool engine oil. Typical signs include oil at the cooler fittings, or coolant that looks like a milkshake. Pressure-test both circuits after a cooler swap — a leak here mixes oil and coolant. Read more

2 Oil Cooler parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Part numbers include GM GENUINE 12675428 and GM GENUINE 12738896.

This table covers the seals at the Oil Cooler Adapter. 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

2 Oil Cooler Adapter Seal parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Listed part numbers: GM GENUINE 12676826 and GM GENUINE 12709792.

This table covers the gaskets that seal the Oil Cooler. 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

GM GENUINE supplies the 3 Oil Cooler Gasket parts for the 2026 GMC Sierra 2500.

This group includes GM GENUINE 12675429, GM GENUINE 12640849 and GM GENUINE 12640850.

This table covers the harness connectors at the Oil Cooler Line. Typical signs include an intermittent fault that moves when you wiggle the plug, green corrosion, or a melted housing. Match terminal count and keyway, not just color. Many families look identical and will not lock. Read more

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Part numbers include GM GENUINE 11588694 and GM GENUINE 11515760.

This table covers the seals at the Oil Cooler. 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

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Listed part numbers: GM GENUINE 97216175 and GM GENUINE 12631281.

This table covers the Oil Dipstick tubes. Read more

This group shows a single part: GM GENUINE 12736677.

This table covers the seals at the Oil Dipstick / Tube. 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

GM GENUINE supplies the 3 Oil Dipstick / Tube Seal parts for the 2026 GMC Sierra 2500.

This group includes GM GENUINE 24504031, GM GENUINE 12676951 and GM GENUINE 12736679.

This table covers the drain plugs in the oil pan. Read more

This group shows a single part: GM GENUINE 55577568.

This table covers the crush washers and gaskets under the oil drain plug. 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

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12616850.

This table covers the caps on the oil filler neck. Read more

This group shows a single part: ACDELCO FC261.

This table covers the gaskets that seal the Oil Filler Cap. 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

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 24100002.

This table covers the Oil Filler tubes. Read more

This group shows a single part: GM GENUINE 12695942.

This table covers the oil filters that screw onto this engine's filter mount. Typical signs include low oil pressure after a service, or a filter that will not spin off because the old gasket stayed on the block. Lube the new gasket and tighten to the spec on the box; a double-gasket install dumps the sump on the first drive. Read more

9 Oil Filter parts for the 2026 GMC Sierra 2500 come from 7 brands — VARIOUS MFR, WIX, FVP and 4 other brands. The "Popular" part is ACDELCO PF63.

The Economy section lists 3 options from FVP, PRO-TEC and VARIOUS MFR — the catalog's value-priced group. FVP R0255 is listed in this group.

The High Performance / Heavy Duty section lists 2 options from MOBIL and WIX — grouped under the catalog's "High Performance / Heavy Duty" designation — the notes column spells out what sets them apart. MOBIL M1212A is listed in this group.

In the Standard Replacement grade, ACDELCO, WIX, HASTINGS / BALDWIN and 1 other brand supply 4 parts: built to original-equipment specification. A representative part number is ACDELCO PF63.

Listed part numbers: ACDELCO PF63, FVP R0255 and PRO-TEC PXL10255, plus the other parts above.

This table covers the Oil Galley plugs. Typical signs include a leak at the drain or glow-plug hole, or a plug that has rounded off. Replace the crush washer and torque to the spec in the notes. Read more

3 Oil Galley Plug parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Part numbers include GM GENUINE 12651561, GM GENUINE 09427693 and GM GENUINE 11569584.

This table covers the Oil Level sensors. Typical signs include a warning lamp, a stored code, or a reading that drops out when the harness is wiggled. Inspect the connector and ground before replacing the sensor — wiring faults are often condemned as bad sensors. Read more

This group shows a single part: GM GENUINE 12696433.

This table covers the Oil Level Sensor Gasket 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

This group shows a single part: GM GENUINE 12638820.

This table covers the Oil Pan bolts. Read more

This group shows a single part: GM GENUINE 11588713.

This table covers the gaskets between the oil pan and the block. 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

2 Oil Pan Gasket parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Listed part numbers: GM GENUINE 12642251 and GM GENUINE 12621086.

This table covers the Oil pumps. Typical signs include noise from the pump, no pressure, or fluid that never arrives at the outlet. Prime or fill the pump as the notes require. A dry start is a common way to kill a new unit. Read more

This group shows a single part: GM GENUINE 12731119.

This table covers the Oil Pump bolts. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 11610074.

This table covers the pickup tubes and screens that feed the oil pump. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12706083.

This table covers the Piston Pin retainers. Read more

This group shows a single part: GM GENUINE 12656762.

This table covers the pushrods that transfer lifter motion to the rocker arms. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12633924.

This table covers the rocker arms that transfer cam motion to the valves. Read more

2 Rocker Arm parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Part numbers include GM GENUINE 12636189 and GM GENUINE 12636190.

This table covers the Rocker Arm nuts. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 11546449.

This table covers the Rocker Arm shafts. Read more

This group shows a single part: GM GENUINE 12648424.

This table covers the Timing Camshaft Gear bolts. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 11610686.

This table covers the tensioners that keep the timing chain taut. Typical signs include belt flutter, a chirp that returns after a new belt, or an arm that no longer damps. Replace the tensioner with the belt at higher mileage. Read more

This group shows a single part: GM GENUINE 11515758.

This table covers the Timing covers. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12739836.

This table covers the Timing Cover bolts. Read more

2 Timing Cover Bolt parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

This group includes GM GENUINE 11588730 and GM GENUINE 11515759.

This table covers the Timing gears. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12698076.

This table covers the Turbocharger Coolant lines. Typical signs include a wet fitting, a rusted pipe, or a pressure loss in this circuit. Flare or thread the new line the way the notes specify; a kinked replacement will fail early. Read more

2 Turbocharger Coolant Line parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Part numbers include GM GENUINE 12728157 and GM GENUINE 12728158.

This table covers the gaskets that seal the Turbocharger. 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

GM GENUINE supplies the 3 Turbocharger Gasket parts for the 2026 GMC Sierra 2500.

Listed part numbers: GM GENUINE 12651147, GM GENUINE 12688018 and GM GENUINE 12688019.

This table covers the Turbocharger Heat shields. Typical signs include a bent shield rubbing a rotor, or rust-through that leaves the backing open. A rubbing shield will eat a new rotor. Straighten or replace it before the wheel goes back on. Read more

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Part numbers include GM GENUINE 12705659 and GM GENUINE 12723833.

This table covers the fasteners that mount the turbocharger. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 11547786.

This table covers the Turbocharger Oil lines. Typical signs include a wet fitting, a rusted pipe, or a pressure loss in this circuit. Flare or thread the new line the way the notes specify; a kinked replacement will fail early. Read more

3 Turbocharger Oil Line parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Listed part numbers: GM GENUINE 12705525, GM GENUINE 12737232 and GM GENUINE 12741013.

This table covers the Turbocharger Oil Line Gasket 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

4 Turbocharger Oil Line Gasket / O-Ring parts for the 2026 GMC Sierra 2500 come from GM GENUINE.

Part numbers include GM GENUINE 12662187, GM GENUINE 12691866 and GM GENUINE 12737100, among others listed above.

This table covers the Turbocharger Up pipes. Read more

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Listed part numbers: GM GENUINE 12688021 and GM GENUINE 12688020.

This table covers the Valve Cover Bolt screws. Typical signs include a rounded head, a seeping bleeder, or a fastener that will not hold torque. Do not force a new screw into a stripped hole — repair the thread first. Read more

GM GENUINE supplies both parts for the 2026 GMC Sierra 2500.

Listed part numbers: GM GENUINE 11548174 and GM GENUINE 11547739.

This table covers the gaskets that seal the valve cover to the cylinder head. 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 12691860.

This table covers the Valve Cover washers. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12654651.

This table covers the lifters / tappets that transfer cam motion to the valves. Read more

This group shows a single part: GM GENUINE 12670435.

This table covers the guides that keep each lifter aligned. Read more

This group shows a single part: GM GENUINE 12729382.

This table covers the springs that close each intake and exhaust valve. Typical signs include a sagging corner, a broken coil, or a clunk from the spring pocket. Replace springs in axle pairs and inspect the seats. Read more

2 Valve Spring parts are listed for the 2026 GMC Sierra 2500, from GM GENUINE and QUALCAST.

Listed part numbers: GM GENUINE 12729741 and QUALCAST 326711.

This table covers the Valve Spring retainers. Read more

One part is listed for the 2026 GMC Sierra 2500 — QUALCAST 555087.

This table covers the keepers that lock each valve-spring retainer to the stem. Read more

One part is listed for the 2026 GMC Sierra 2500 — GM GENUINE 12636193.

This table covers the seals on each valve stem that control oil into the guides. 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

This group shows a single part: GM GENUINE 12633926.