How to replace the thermostat on a 4.3L engine on Chevrolet Silverado 1500?

To replace the Thermostat in a 4.3l engine, first drain the cooling system. Release the air cleaner outlet duct clamp at the mass airflow/intake air temperature (MAF/IAT) sensor and remove the positive crankcase ventilation (PCV) hose along with the air cleaner adapter nut. Pivot the air cleaner outlet duct upward till the hinge clip comes off the Throttle Body lip. Retrain the water outlet hose clamp at the water extent and pull the inlet again, the water outlet studs and the water outlet hose afterward. Remove Thermostat and clean sealing surfaces of water outlet, as well as the sealing surfaces of the Intake Manifold, discarding the o-ring seal. In case of replacement, however, take off the original Thermostat by unbolt the water outlet, leaving the o-ring seal in place. Then, put on a new o-ring seal and replace the Thermostat. Reinstall the water outlet. Attach the water outlet studs, tightening them to 25 nm (18 ft. Lbs.), and then connect the inlet hose to the water outlet and mount inlet hose clamp. Allow the hinge clip to match with the lip running down from the Throttle Body, and move the air cleaner outlet duct down to get the mounting stud into it so that you can then fit the air cleaner adapter nut and the pcv hose. Close the air cleaner outlet duct clamps on the maf/iat sensor to 4 nm (35 inches lbs), add fluid into the cooling system and check for leaks.

OEM Chevrolet Silverado 1500 Thermostat

Engine Coolant Thermostat

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Chevrolet Silverado 1500 Thermostat Housing
Part Number: 12674639
$57.18 MSRP: $120.68
You Save: $63.50 (53%)
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Product Specifications
- Other Name: Outlet Assembly-Water Pump (W/Thermostat); Engine Coolant Thermostat Housing; Thermostat Housing Cover; Water Outlet; Thermostat; Outlet, Engine Coolant Pump
- Replaced by: 19474058
- Replaces: 12666569, 12671393, 12657137
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2014-2019 Chevrolet Silverado 1500 | Custom, Custom Trail Boss, High Country, LS, LT, LT Trail Boss, LTZ, RST, SSV, WT | 6 Cyl 4.3 L FLEX, 6 Cyl 4.3 L GAS, 8 Cyl 5.3 L FLEX, 8 Cyl 5.3 L GAS, 8 Cyl 5.3 L MILD HYBRID EV-GAS (MHEV), 8 Cyl 6.2 L GAS
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Chevrolet Silverado 1500 Thermostat
Part Number: 12632948
$29.24 MSRP: $54.92
You Save: $25.68 (47%)
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Product Specifications
- Other Name: Thermostat, Engine Coolant Temperature
- Replaces: 12257859, 12563335, 12557859, 12597583, 12551472
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 1999-2013 Chevrolet Silverado 1500 | Base, LS, LT, WT | 6 Cyl 4.3 L GAS
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Chevrolet Silverado 1500 Thermostat
Part Number: 89018168
$39.67 MSRP: $78.71
You Save: $39.04 (50%)
Ships in 1-3 Business Days
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Product Specifications
- Other Name: Engine Coolant Thermostat; Thermostat, Engine Coolant Temperature
- Replaces: 89017851
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2019-2023, 2007-2013 Chevrolet Silverado 1500 | Custom, Custom Trail Boss, High Country, Hybrid, LS, LT, LT Trail Boss, LTZ, PPV, RST, SSV, WT, XFE, ZR2 | 6 Cyl 4.3 L GAS, 8 Cyl 4.8 L FLEX, 8 Cyl 4.8 L GAS, 8 Cyl 5.3 L FLEX, 8 Cyl 5.3 L GAS, 8 Cyl 6.0 L FULL HYBRID EV-FLEX (FHEV), 8 Cyl 6.0 L FULL HYBRID EV-GAS (FHEV), 8 Cyl 6.0 L GAS, 8 Cyl 6.2 L FLEX, 8 Cyl 6.2 L GAS
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Chevrolet Silverado 1500 Thermostat Unit
Part Number: 12600171
$22.45 MSRP: $42.18
You Save: $19.73 (47%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Thermostat, Engine Coolant Temperature; Thermostat
- Replaces: 12581595
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2004-2006 Chevrolet Silverado 1500 | Base, Hybrid, LS, LT, SS, WT, Z71 Off-Road | 8 Cyl 4.8 L GAS, 8 Cyl 5.3 L FLEX, 8 Cyl 5.3 L FULL HYBRID EV-GAS (FHEV), 8 Cyl 5.3 L GAS, 8 Cyl 6.0 L GAS
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Chevrolet Silverado 1500 Thermostat
Part Number: 19420815
$39.50 MSRP: $78.40
You Save: $38.90 (50%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Thermostat Kit, Engine Coolant Temperature
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2023 Chevrolet Silverado 1500 | Custom Trail Boss, High Country, LT, LT Trail Boss, LTZ, PPV, RST, WT, ZR2 | 8 Cyl 5.3 L FLEX, 8 Cyl 5.3 L GAS, 8 Cyl 6.2 L GAS

Chevrolet Silverado 1500 Thermostat

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Chevrolet Silverado 1500 Thermostat Parts Questions & Experts Answers

Thermostat Unit
12600171
Q: How to replace the thermostat on a 4.3L engine on Chevrolet Silverado 1500?
A: To replace the Thermostat in a 4.3l engine, first drain the cooling system. Release the air cleaner outlet duct clamp at the mass airflow/intake air temperature (MAF/IAT) sensor and remove the positive crankcase ventilation (PCV) hose along with the air cleaner adapter nut. Pivot the air cleaner outlet duct upward till the hinge clip comes off the Throttle Body lip. Retrain the water outlet hose clamp at the water extent and pull the inlet again, the water outlet studs and the water outlet hose afterward. Remove Thermostat and clean sealing surfaces of water outlet, as well as the sealing surfaces of the Intake Manifold, discarding the o-ring seal. In case of replacement, however, take off the original Thermostat by unbolt the water outlet, leaving the o-ring seal in place. Then, put on a new o-ring seal and replace the Thermostat. Reinstall the water outlet. Attach the water outlet studs, tightening them to 25 nm (18 ft. Lbs.), and then connect the inlet hose to the water outlet and mount inlet hose clamp. Allow the hinge clip to match with the lip running down from the Throttle Body, and move the air cleaner outlet duct down to get the mounting stud into it so that you can then fit the air cleaner adapter nut and the pcv hose. Close the air cleaner outlet duct clamps on the maf/iat sensor to 4 nm (35 inches lbs), add fluid into the cooling system and check for leaks.