The most common cause is the intake manifold gasket. You need to look at the front corners of the intake were it meets the heads and see if there is coolant leaking at those points if so then replace the intake gaskets. You also need to check the heater hose fitting that screews into the left top front of the intake for a leak. It will have a black rubber hose hooked to it. It is common for them to leak too. The water pump may also be your problem, check it too. If it's leaking then coolant will be running down the lower radiator hose.
Low coolant
The 1995 Chevy Silverado coolant sensor is located on the front of the engine. The coolant sensor will be a few inches above the thermostat housing.
A 2000 Chevrolet Silverado with a 5.3 liter engine takes 13.4 quarts of coolant. It is suggest that the coolant be mixed 50/50 with water.
50/50 mixture of DEXCOOL and water
on a 2002 Chevy silverado with a 4.6 liter v6 where is the coolant sensor for low coolant. I have a light on and check the overflow and their is coolant but don't know if their is another one or not.
On driver side of block by the bolt in exhaust manifold closest to front of vehicle
Dexcool, Orange color.
It's on the coolant reservoir.
The coolant temp sensor on a 2002 Silverado with the 6.0 engine is located on the drivers side cylinder head close to the front of the cylinder head.
If coolant level gets too low the engine can overheat.
If you are sure that it did not freeze and crack the block, Then the intake manifold gasket is leaking. That is a common problem with the vortec Chevy engines. You need to replace the gasket with a factory Chevy gasket from the dealer.
Regular coolant or a global coolant will work also. Thanks for your answer. I failed to mention that I have yellow in radiator now, should I stay with yellow? Is there harm in mixing colors?