I need some help. I have a 2000 Blazer LT. It has recently started overheating. In the last two weeks I have replaced the water pump, fan clutch, radiator cap and thermostat. While I had it all apart I put the garden hose in the top radiator hose and water flowed out of the two engine ports where the water pump is mounted, I turned the hos around and water flows from the top of the radiator and out the bottom hose, I have flushed out the heater core and water flows through it as well. Is there anything I could be missing that would be makiang it overheat before I put it all back together.

 

There are several more places where water could be leaking. I even heard on this forum of a heater hose that would only leak when hot by spraying single jet of coolant onto an exhaust manifold leaving hardly any evidence.

The definitive way to check your cooling system is to borrow a cooling system pressurization kit from an auto parts store and pressurize the system when it is cool. You can then quantify the leak by how quickly the pressure drops and more easily find where the leak is since the engine and coolant will be cold and you can more easily look around the engine compartment.

One place where you would not see a leak is if the coolant is leaking into the engine. This can happen due to a leaking lower intake manifold (LIM) gasket. This was a common problem on the late 90s Blazers. This might have been a problem as late as 2000 but I'm not sure of that.

Good luck and keep us posted.

 

Thank you for your response I will do that this weekend and continue the pursuit of the mysterious leak.

 

How hot was it getting? How did the coolant look, and gunk in there? Could be the radiator stopping up internally or lots of dirt and debris clogging it from the outside killing air flow. Some AC coil cleaner wouldn't hurt to clean the fins out.