Where is my coolant going?

I took out my thermostat awhile back cause my truck was getting hot. A few weeks later I noticed it was getting hot again... I was low on coolant. Then again a few weeks after that I was low again. I can't see it physically leaking out anywhere and the reservoir is also always empty... Any ideas?

could have a pin hole in the rad

I don't think so... Because it would be spraying out when the truck got hot, right?

more than likely. i had a leak once due to a clamp being slightly loose and couldnt even see the coolant dripping out

Hmm... This seems like a lot of coolant lose for something like that. That's why I'm dumbfounded.

ok put a new thermostat in and replace the radiator cap ...it sounds like the cap is bad and your slowly losing wather through that you wont notice it cause your driveing and its evaporiting past the cap...and never run these things without a thermostat..they are cheap

it does sound like the cap is bad, because it willl cause the coolant to boil and evaporate a lot. the system has to stay pressurized for it to work properly.

any white smoke on startup? could be a blown head gasket if you do. the water is going out your exhaust as steam (white smoke). if not, then its your cap like the others said.

Hmm... It might be the cap then. No smoke at all.

Exhaust smell sweet? Check your heater core, it could all be leaking inside the cab.