Chevrolet put the 5.7-liter engine in the 1999 Suburban 1500 as standard equipment, and offered a 6.5-liter turbodiesel as an option. In anticipation of a redesign for 2000, the 1999 model saw no changes over the previous model year. Use an ample-sized drain pan to catch the coolant when you change the radiator in your Suburban. This large sport utility vehicle has a large-capacity cooling system.
After the engine cools, place a large-capacity catch pan beneath the radiator petcock at the lower driver-side corner of the radiator. Hold a rag over the radiator pressure cap, and unscrew it to the first detent. Allow any residual pressure to escape the system before fully removing the cap. Open the radiator petcock and allow the coolant to drain.
Using a ratchet and socket, remove the upper fan shroud bolts and the upper shroud. Remove the upper radiator bracket bolts, and remove the brackets and rubber isolators. Inspect the rubber for deterioration or damage, and replace as necessary.
Loosen the upper and lower radiator hose clamps, using a nut driver, and remove the hoses from their barbs on the radiator. Inspect the inside of the hoses for damage or delamination and replace them if necessary. Lead the lower hose down to the catch pan to catch the remaining coolant.
Using a flare-nut crow's-foot wrench and ratchet, loosen the flare nuts and remove the engine oil and transmission oil cooler lines from the radiator. Move the lines aside slightly to gain clearance to remove the radiator, but don't kink them.
Remove the lower fan shroud bolts, using a ratchet and socket, and lower the shroud away from the radiator. Remove the coolant overflow tube from the radiator pressure cap tower. Lift the radiator straight up and out of the engine compartment.
To install it, lower the radiator into position, and guide it onto the lower brackets and rubber isolation mounts. Install the lower fan shroud and bolts, then torque them to 71 inch-pounds, using an inch-pound torque wrench and socket.
Hand-thread the engine oil cooler lines and the transmission oil cooler lines into their fittings on the radiator. Torque the oil fittings to 18 foot-pounds, and the transmission lines to 19 foot-pounds, using a foot-pound torque wrench and flare-nut crow's-foot.
Push the radiator hoses onto their hose barbs on the radiator. Position and tighten the hose clamps.
Install the upper radiator bracket and rubber isolators, then tighten the bolts securely. Install the upper radiator shroud and bolts, then torque the bolts to 71 inch-pounds.
Push the coolant overflow tube onto its barb on the radiator pressure cap tower. Add approximately 4.5 gallons of a 50-50 solution of water and coolant. Install the radiator cap. Fill the coolant reservoir up to the "Full" mark.
Set the heater controls to "Full Hot." Start the engine and check for leaks. Set the heater blower speed to "High." Allow the engine to warm up to operating temperature. Turn the engine off and allow it to cool completely. Check the level in the coolant reservoir, and add coolant as necessary.
Repeat Step 12 until the level in the coolant reservoir stabilizes and you no longer have to add coolant after cooling down.
