I am having considerable trouble with my cooling system. My coolant is overheating and boiling out of the overflow/reserve tank. And my temp gauge shoots straight into the red pretty much all of the time.
I have flushed the coolant and also flushed it with the Prestone radiator cleaner, I also replaced the thermostat.
I am certain that the problem is the water pump. Is there any way you can do a quick check to see if it is actually the water pump that is messed up?Without removing it.

And also, I have the Lt1, which comes with GM part #12527739 which is the stock water pump on the 95 Z28. Can I buy a GM part #12527741 a high flow water pump (summit racing) and install it without having to modify anything else?
I can buy the parts on line soon... But, do not know exactly if the two parts are easily interchangable. I called the dealership and they were asking over $100 what of the others were asking.Any info would be helpful.
Thank you.

 

While the engine and coolant is cold, take the radiator cap off, fill it to the top, and start the engine. If it starts bubbling right away and starts coming out of the radiator, then more than likely you have a blown head gasket. Try this first to rule it out before going any further.