Car sucking up antifreeze like its cool.

so the coolent in the overflow is what is leaking? have you checked for a leak in the overflow can? check the water pump around the weep hole? passenger floor still dry?

Sorry to say but i think its a head gasket, my car did the same thing and thats what it was. It sarted out just like yours no smoke nothing on the ground and nothing i could see in the oil. One way to tell is make sure its full start the car take off the cap and get the car up to temp and look for bubbles in the coolent. It doesnt always work but it could help track things down.

I dont think its the head gasket if she aint smoking at all. I had the same problem as this guy after i did my H/C/I install. Turned out that I didnt do my lower intake gaskets right and thats where all my coolant was going. You might have a lower intake gasket leak around the coolant passages. That would be my guess.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a
jumper wire or paper clip to put the computer into test mode. Start
the engine and let it go through the normal diagnostic tests, then
quickly press the throttle to the floor. The engine RPM should exceed
2500 RPM's for a brief second. The engine RPM's will increase to about
1450-1600 RPM and hold steady. The engine will shut off power to each
injector, one at a time. When it has sequenced through all 8 injectors,
it will flash 9 for everything OK, or the number of the failing cylinder
such as 2 for cylinder #2. Quickly pressing the throttle again up to
2500 RPM’s will cause the test to re-run with smaller qualifying figures.
Do it a third time, and if the same cylinder shows up, the cylinder is
weak and isn’t putting out power like it should. See the Chilton’s Shop
manual for the complete test procedure

Here's the link to dump the computer codes with only a jumper wire
or paper clip and the check engine light, or test light or voltmeter.
I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.



89 through 95 cars have a working Check Engine light. Watch it instead of a test lamp.




Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder
balance test. Low compression on one of these cylinders rules out the
injectors as being the most likely cause of the problem. Look at cylinders
that fail the cylinder balance test but have good compression. These
cylinders either have a bad injector, bad spark plug or spark plug wire.
Move the wire and then the spark plug to another cylinder and run the
cylinder balance test again. If it follows the moved wire or spark plug,
you have found the problem. If the same cylinder fails the test again,
the injector is bad. If different cylinders fail the cylinder balance test,
you have ignition problems or wiring problems in the 10 pin black &
white electrical connectors located by the EGR.

How to do a compression test:
Only use a compression tester with a screw in adapter for the spark
plug hole. The other type leaks too much to get an accurate reading.
Your local auto parts store may have a compression tester to rent.
If you do mechanic work on your own car on a regular basis, it would
be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the
throttle wide open, crank the engine until it the gage reading stops
increasing. On a cold engine, it will be hard to tell what's good &
what's not. Some of the recent posts have numbers ranging from
140-170 psi. If the compression is low, squirt some oil in the cylinder
and do it again – if it comes up, the rings are worn. There should be
no more than 10% difference between cylinders. Use a blow down
leak test (puts compressed air inside cylinders) on cylinders that
have more than 10% difference.

See the link to my site for details on how to build your own blow
down type compression tester.

I lost a lot of water due to my water pump leaking at the seal...it just went 'kapoowie..." one day, but got gradually worse.

But it would leak below the water pump, mine would almost literally pour out...

Yours may be just starting to leak...check for drips after you stop the car. Lay on the ground and take a peak with a flashlight...

I hope it's not a headgasket...

To save a few bucks until you figure out the problem, run some distilled water or tap water instead having to pay for antifreeze so much...

I had a leak that was hard to find, turned out to be the coolant hose for the egr spacer that goes on the back bottom of the intake. It started out slow, then got pretty bad, and dad found it during a oil change while it was on the lift.