Just walked out to my truck, (2000 GMC Sierra 1500 Z71, Reg Cab), and have a big puddle of orange, Dex-cool coolant all the way out past my passenger door. I had drove it approx 2hrs earlier. There was no rising temp and nothing of note. The only thing that has caught my attention recently is a whine that started 4 days ago when truck is started, then after a few it goes away but earlier today it actually continued as I drove and the more my speed increased the whine would going higher in pitch with my increase in mph. Until today it sounded like a fan or belt type whine but I've never heard it get higher with mph and continue while driving.....so I've had someone tell me they think the noise is my water pump and that could also account for the coolant leak tonight. Any input, ideas, thoughts, etc would be greatly appreciated, I can't be without my truck so I've got to get a quick jump on this...thank ya much in advance.

 

Try to find out the location of the leak and it will narrow down the problem.