It seems my cooling system is working okay, the needle on the gauge never moves hotter than the middle. But the overflow tank (expansion tank) doesn't hold more than a puddle of fluid at any one time. If I add to it, then a few miles down the road it's gone. But my radiator never has less coolant, and there are no leaks in the hoses, my thermostat works fine. I thought maybe my gauge was faulty but if that were the case my engine would be toast by now, right? Also, the PO replaced the radiator with one by GM many miles ago. Does anyone know what's up with this??? Thanks, and enjoy your weekend. Or else. LOL

 

Pull off the overflow reservoir, fill it with water, and prop it upright someplace where you can see if it leaks. If it does, either try to patch it or get one from a junkyard. If it doesn't leak, then there must be a leak in your coolant loop - a coolant pressure test may help you to find it.

 

Wait! On second thought I really don't know that the system is working fine....

the hose coming off the radiator (bottom) gets warm but not hot. Don't both upper and lower hoses get too hot to touch when engine is warmed up?? So I'm suspecting the flow of coolant/antifreeze is not right.

But doesn't the pump push/pull the fluid through the system? Then either the pump isn't doing its job (though it isn't leaking or making noise) or my radiator is plugged up. Probably one or the other... If not, what do you think?

By the way, should the electric fan pull air through the radiator, or blow on the radiator?? And also, where is the coolant temp sensor located on the engine?? THANKS!

 

In addition to the water pump & clogging, a stuck thermostat also could prevent coolant flow through the radiator. Hard to explain no overheating if theres no radiator flow, though.

 

The bottom hose should be significantly cooler than the upper hose since heat from the coolant has been removed by the radiator and the cooler water leaves through the lower hose, being pulled out by the pump.

Can't say about the electric fan... assuming you mean the auxillary fan for the air conditioning, I believe it pushes through the a/c condenser. The stock belt-driven fan pulls air through the radiator.

The coolant temp sensors are located: for the ECU, it's on the front edge of the intake manifold, below the upper radiator hose, pointing towards the radiator; and for the dash gauge is located between #2 and #3 cylinders, close to the head, pointing up.