2003 CRV 46,000 mi. After noticing my coolant was low, I filled the radiator and the the reservoir to the MAX line. After driving for a half hour I find the reservoir empty. I've done this several times. I see no signs of leakage anywhere. No warning light comes on and the temperature gauge reads normal. Any ideas out there? Thanks in advance.

 

If there are no leakage seen on the ground, none on the engine area, it may be leaking into the crankcase. check oil add cover for cream color under cap, check oil for color change. also may be leaking into combustion chamber via head gasket, check exhaust for steam after normal warm up, or excessive water dripping out of the tail pipe. with the engine cool to clold, fill up rad to top. start engine and view water level for excessive air or bubbling at the top of the radiator. take a compression check to see if you have any low compression in any cylinder. Did you get the water temp ever to the red area, or very hot??

 

leak could be going into the engine block for ......check the oil's color and quantity.. if the oil is a whitish-gray, the coolant may be leaking into it...

You could also have a bad radiator cap that's allowing it to escape..

 

Look at the exhaust,what color if any is it,white would be coolant,if that's the case your coolant is indeed escaping into the combustion chamber. As stated it will show up as a white/yellow foam on the dip stick /oil cap.