Coolant dissapearing coolant keeps running low and is not leaking out anywhere visable so where is it going. my mechanic ran test and has no answeres either.

add coolant let it run til the thermostat opens to see where the level is at if you need to add more or not

do not ever run the vehicle and check the coolant, coolant will go everywhere. leave the vehicle off and make sure its cold and then open radiator cap if radiator and overflow are empty then fill the radiator full and fill overflow to the fill line. put the cap back on then start vehicle. if no leakes then you where just low on coolant.

Doesn't sound like it ran hot enough or long enough to crack or warp the head. If there is a crack, the engine will continue to overheat. If a warped head, car would probably run rough, the affected cylinders would likely have little or no compression, there would be a noticeable miss, and overheating would continue.
Why the low coolant? It's a sealed system, so should never have to add coolant, other than a small loss from evaporation in the overflow tank. Monitor the level closely for the next few days. Note the level in the overflow tank to see if it drops over time. Leaks can be external anywhere in the coolant system-engine, radiator, hoses, heater core- or internal in the engine-head gasket failures can cause coolant in the cylinders (white smoke out the exhaust), or coolant in the oil (oil will have a milky brown look to it), or oil in the coolant (will see traces of oil in the radiator).
A couple of tests may be called for. A pressure test of the coolant system will check if the system holds pressure as it should-about 15 psi. If pressure does not hold, there is a leak somewhere. Water pumps usually leak through the weep hole when they fail. A radiator leak would show up when pressure is applied. If pressure does hold, check if you have a good radiator cap-the cap is what seals the system so pressure will maintain. Coolant under pressure raises it's boiling point by about 10 degrees, so is critical to keep the system under pressure.
If you suspect further problems-losing coolant or continued overheating-then have the chemical test done to check for exhaust gasses in the coolant. Basically a check if the head gasket is good, a simple test done at the radiator cap opening with a special fluid that changes color if hydrocarbons are present in the cooling system.
Or you could have a compression test of the cylinders to check the internal mechanical condition-not only tells you if head gasket is good, also tells you a lot about engine condition-even,. balanced, good compression in all cylinders translates into good power output-rings are good, valves are sealing good, all systems go.
The cooling system: water pump, thermostat, radiator, hoses, heater core and hoses, radiator cap, overflow tank, and the cooling fans and associated wiring. Make sure everything is working right and you'll be good to go.

coolant under the manifold is a hole ( corrosion)and if water is coming out then uncontrolled air can get in giving you the running problems. Have a compression test done to check for blown head gasket. Have a coolant pressure test done to find the leaks

Have a cooling system pressure test done Check for leaks at the welsh plugs in the side of the block and at the back of the head/s.

if you haven't had any coolant in your car for a week and you have been driving it you may have blown your head gasket, even though you haven't got 'milkey goo' on your oil dip stick. check for goo under your oil cap to see and have it tested at a garage. but from what ive read im almost certain its your head gasket. hope this helps you and beware of the dangers of a running engine so keep hands and loose clothing out of the way of moving parts and engines get very hot so be careful what you touch.

if you see no visable leaks, or puddles on ground under vehicle to pinpoint leak, but keep having to add coolant I would suspect intake gasket leak. coolant burning through exhaust system, when really bad excessive white smoke from exhaust will be noticable

DW Mylin

There could be a leak, to find out you must pressure test the cooling system. Also test the cap.

If you have no leaks you can see, you have a internal problem.
1) Head gasket not sealing off properly
2) Cracked head and/or block
Test
Purchase Block leak tester, for your coolant system and follow instruction. If it test reveals combusting gas in coolant. You will need to pull Cly. head for further testing.

Could be buring coolant from headgasket leak. thats the only other way coolant can leave your engine besides a leak.

Side note:
I strongly reccomend in the future not to use ne kind of coolant stop-leak stuff. you have small passages coolant needs to go through and that stuff also cloggs up those areas. alot of people dont think that far ahead. so alittle info for the future for you. it also cloggs up your heatercore and radiator. and will cause faster corrosion in those areas.