Slow Coolant Leak on 2.7L 4x4 Getting Worse

Hey Guys, I have a 1997 4x4 5-speed manual with 250,000 miles. It has the 2.7 engine. I have been having a slow coolant leak for a year or more that just seems to get worse. There is no puddle or spray on the engine or anything obvious. The oil is fine. Truck runs smooth. Gas mileage is close to 25 mpg. I can't seem to figure where my anti-freeze is going. Original water pump also. No over heating problems. I did replace the radiator about 15,000 miles ago but I had the problem even before. Again, no wet spots from anti-freeze anywhere I can find.
Thanks in advance for any advice!

 

I bet its weeping from your waterpump, drying before it drips. take a look at the weep hole and your should see a stain.

 

theres a pipe plug on the passenger side of the block that ive had rattle loose on me before. itll dribble and never leave a puddle too.

if its an original water pump my money is on that though.

 

Itll also drip and not puddle if leaking from the thermostat housing

 

If your radiator cap is bad it won't seal and you will lose coolant/water as steam

 

Borrow a pressure tester from a parts house that has a tool loaner program. Simple and accurate.

 

How is your truck when you start it when it's cold. My Tacoma (2.7) would hesitate ever so slightly then smooth out on cold starts. My coolant overflow tank was also low. No other indications of head gasket. No milky oil or white smoke etc...turns out. Head gasket! Had about 200k when it went out. Also these radiators have plastic end caps. Check to see if there's a leak anywhere. If you don't see any leaks then I would do a pressure test like Clearwater Bill said.

 

I bought a water pump and tore it down to replace it but after taking the belts off I got a mirror and looked for stains from the weep hole. No stains at all. It will occasionally steam when I turn it off but the last time it did I wasn't in a position to look at it very well. Runs great and no oil in the water. I don't think the exhaust is an whiter than normal. Can't find any leaks in hoses. Replaced radiator last year so it's good.