This one is a real mystery. I replaced the HGs with the good ones and everything is tight. New radiator, cap , t-stat. I thought I had a pinhole leak in the heater core and (I know its not recommended) added some Aluminum stop leak which actually did the job.

 

Now the engine runs pretty cool (about 1/3), no water in the oil, no white smoke, no external leaks, no wet floors from the heater core, but I keep losing water. If I drive 50 miles, I put in a pint of coolant. When I drive, I hear the sound of water sloshing around when I go around turns. The heater never really feels hot. But the radiator loses a substantial amount of water and has even gone almost dry leading to a hot engine indication, but a cold radiator and cap.

 

I realize there are only so many places water can go, but without a single drop on the outside and no indication of an internal leak, I am baffled.

 

 

Possible invisible leaks-

Intake gaskets.

fancy o ring between throttle body and intake.

Crack in head exhaust port.

These can leak and not cause white smoke, when small.

small leak onto top of engine block.

Possible invisible leaks-

Intake gaskets.

fancy o ring between throttle body and intake.

Crack in head exhaust port.

These can leak and not cause white smoke, when small.

small leak onto top of engine block.

Keep an eye on your rear view mirror next time you're climbing a hill. If you see any steam out the back while going up hill (easiest noticed at night with another car lighting up the back of your car) one of the small manifold cooling lines is cracked and leaking a little on to the top of the motor. It doesn't drop off until you go up hill.

So this summer after my first head gasket job, I was loosing coolant and couldn't see where. No puddles, no dripping but  the coolant was definitely going somewhere. It turned out to be a tiny coolant line running from the intake to the block, possible the same one 175eya is referencing. It  would leak out onto the top of the block and cook off so thats why I never saw any dripping. Cross your fingers for this being the problem, as it was a 2-3 dollar 5 minute fix. 

Yep that hose is a pain in the ***. Thing is they don't seem to leak at idle so if you look while it idles, no leak. Rev the engine and it leaks.

Edited January 15, 201511 yr by MR_Loyale

It turned out to be a tiny coolant line running from the intake to the block, possible the same one 175eya is referencing. It would leak out onto the top of the block and cook off so thats why I never saw any dripping.

That would be the one!

10 years ago, mine had a pin hole in it and had steam coming out of it... but only when up to operating temp (maybe slightly over, as I was low on coolant again)    I too, looked for a water leak for 2 weeks.

My conclusion is ....   Steam dissipates - Water puddles.     

I'll check the top of the manifold. I wouldn't be surprised if it wasn't leaking water under the carb and the car was running with water injection (minus the power increase I would expect).

Sometimes on radiators with plastic tanks, the seem will open up a bit when hot and you would loose coolant (under heat and pressure). When you just sat and idled the car or did a leak down test, you will never find the leak. What can do is a dye test, as that would leave a trail of the coolant even after things cooled down.