Engine Cooling System: Maintenance Chevrolet Silverado 2500

Drain & Fill Procedure

Important: If you do not follow the procedure below, a low or high coolant level condition and/or vehicle damage could result.

1. Park the vehicle on a level surface.
2. Follow the steps below in order to remove the surge tank fill cap: 2.1. Slowly rotate the cap counterclockwise. 2.2. Stop rotating and allow the hissing to stop. 2.3. After all hissing stops, continue turning counterclockwise in order to remove the cap.
3. Open the radiator drain cock.
4. Allow the system to drain completely.
5. Inspect the engine coolant for the following: Discolored - follow the flush procedure below. Normal in appearance - continue with the next step. NOTE: When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner at 50,000 km (30,000 mi) or 24 months. The following notice applies only to the 4.8L, 5.3L and 6.0L engines. NOTE: DO NOT use cooling system seal tabs, or similar compounds, unless otherwise instructed. The use of cooling system seal tabs, or similar compounds, may restrict coolant flow through the passages of the cooling system or the engine components. Restricted coolant flow may cause engine overheating and/or damage to the cooling system or the engine components/assembly.
6. Close the radiator drain cock.
7. Fill the system through the surge tank opening.
8. Pre-mix a 50 to 60 percent solution of DEX-COOL® and clean, drinkable water.
9. Slowly add the pre-mixed solution to the surge tank until the level is slightly above the surge tank split line.
10. Start the engine.
11. Idle the engine for 1 minute.
12. Loosely install the surge tank cap. Do not allow the system to build up pressure.
13. Cycle the engine from idle to 3000 RPM in 30 second intervals until the engine coolant reaches 99°C (210°F) and the thermostat opens.
14. Shut off the engine.
15. Refer to step 3 in order to remove the surge tank cap.
16. Start the engine.
17. Idle the engine for 1 minute. Fill the surge tank to 1/2 inch above the COLD FULL mark on the surge tank.
18. Install the radiator surge tank cap.
19. Cycle the RPM. Idle the engine to 3000 in 30 second intervals until the engine coolant reaches 99°C (210°F).
20. Shut off the engine.
21. Top off the coolant, as necessary, to 1/2 inch above FULL COLD mark on the surge tank.
22. Rinse away any excess coolant from the engine and the compartment.
23. Inspect the concentration of the coolant.

Scheme 160

Scheme 161

Scheme 162

1. Drain the cooling system, refer to the above procedure.
2. If equipped with the 4.3L engine, remove the left and right engine block coolant drain plugs.
3. If equipped with the 4.8L, 5.3L or 6.0L engine, remove the left and right engine block coolant drain plugs.
4. If equipped with the 6.6L diesel engine, remove the left and right engine block coolant drain plugs and washers.
5. If equipped with the 8.1L engine, remove the left and right engine block coolant drain plugs.
6. Remove the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (4.3L Engine)»(ref-176275-S06041356422005050500000) , «Coolant Heater Replacement (4.8L, 5.3L & 6.0L Engines)»(ref-176275-S07891600422005050500000) , «Coolant Heater Replacement (6.6L Engine)»(ref-176275-S08385762082005050500000) or «Coolant Heater Replacement (8.1L Engine)»(ref-176275-S24041460912005050500000) .
7. Allow the engine block to drain completely.
8. Apply sealant to all drain plugs, EXCEPT the 6.6L diesel engine plugs.
9. Re-install the engine block coolant drain plugs. Tighten the 4.3L engine block coolant drain plug to 20 N.m (15 lb ft). Tighten the 4.8L, 5.3L or 6.0L engine block coolant drain plug to 60 N.m (44 lb ft). Tighten the 6.6L diesel engine block coolant drain plug to 18 N.m (13 lb ft). Tighten the 8.1L engine block coolant drain plug to 60 N.m (44 lb ft).
10. Install the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (4.3L Engine)»(ref-176275-S06041356422005050500000) , «Coolant Heater Replacement (4.8L, 5.3L & 6.0L Engines)»(ref-176275-S07891600422005050500000) , «Coolant Heater Replacement (6.6L Engine)»(ref-176275-S08385762082005050500000) or «Coolant Heater Replacement (8.1L Engine)»(ref-176275-S24041460912005050500000) .
11. Fill the cooling system, refer to the above procedure.

Flushing

Important

1. Do not use a chemical flush.
2. Store used coolant in the proper manner, such as in a used engine coolant holding tank. Do not pour used coolant down a drain. Ethylene glycol antifreeze is a very toxic chemical. Do not dispose of coolant into the sewer system or ground water. This is illegal and ecologically unsound.
3. Various methods and equipment can be used to flush the cooling system. If special equipment is used (such as a back flusher) follow the manufacturer's instructions. However, always remove the thermostat before back flushing the system.

1. Block the drive wheels.
2. Place the transmission in park (P) or neutral (N).
3. Engage the park brake.
4. Run the engine until the thermostat opens.
5. Stop the engine.
6. Follow the drain and fill procedure using only clean drinkable water. Repeat the procedure if necessary, until the fluid is nearly colorless. Refer to «Draining & Filling Cooling System»(ref-176275-S33324703732005050500000) .
7. Fill the coolant reservoir to the FULL HOT mark.
8. Fill the cooling system. Refer to «Draining & Filling Cooling System»(ref-176275-S33324703732005050500000) .