Alright....I've got 53k on the ticker of my '03 Silverado. I don't know exactly what's going on, but for the past few months I've had disappearing coolant. I'll top the reservoir off, and after a few weeks, my "low coolant level" display comes on..the truck doesn't run hot..nor does it smoke from the exhaust..no drops on the ground..I thought it was the sensor was screwed up. I open up the reservoir, and it's BONE DRY.. From time to time I can smell the odor of coolant, mainly when the display light is on..since there's no visible leaking..and, I don't see anything on the motor itself, I am completely stumped. My roommate said his dad's truck does the same thing...is this a common occurance, or what??

 

This happened on my jeep a while back, found out it was a pinhole leak in the upper radiator hose and the coolant was somehow vaporizing and leaking out. Got me..

 

cheak the water pump

 

seems like you could be burning the coolant in your cylinders from a leak. It's just small enough not to cause a reduction in performance.

 

I had 2 LT1 f-bodys that did the same thing. Turned out to be tiny leaks from the water pump.

 

The Most common on these engine seems to be the water pump, and you wont usualy see any drip on the ground either.
Next would be a head gasket leaking. I would lean more towards water pump though. It's usualy the gaskets and not the pump itself. Depending on how much you want to spend, you can change just the gaskets or do the pump.

 

water pump gasket

 

+1...the gaskets where the water pump mounts to the block are a common failure...

 

Thanks guys. After I posted this, I did a search on the site, but there was a couple of different scenario's, with different results. How hard is it to replace the water pump gasket? And, is there a sure fire way to check and see if this is indeed where it's leaking from?

 

Water pump gaskets aren't very hard to replace. Stick you head under there with a light and try to look up from below to the water pump. If it is leaking you most likely will see signs of where the coolant has run down along the block, pan and other parts. It usually doesn't leak enough to make it to the ground.