My car has been eating up coolant recently. I would notice my overflow tank slowly emptying but now it seems to be getting worse. I noticed it was empty on monday night so I filled it up a bit past the "max" mark. I daily drive the car about 20ish miles M-F and just now on the way home my checklight came on and I noticed the tank was empty. I set the check light to come on at 202 degrees in s300. I boost on it sometimes when changing lanes to pass and when I can a third gear pull to around 7500rpm. From what I can see there are no leaks. I am thinking that maybe the head gasket is toast but I would think coolant would get pushed out into the overflow tank instead. What should I check for? I did not have any bad overheating issues before this...cruising around 190* and it gets up to 197* idling in traffic.

 

the water is loosing somewhere
find it

 

check your exhaust smoke, put UV dye in your coolant, run it a little bit, turn off the lights, shine a uv light so you can EASILY see where the leak is,

if your thoroughly checked the lines and didnt see a leak,

the leak is inside your block:

you need to remove your head and check the headgasket cause it might be going out, or blown already

 

head gasket ?

 

... yes

if your headgasket is going out/blown, your cylinders are surrounded by coolant and when your headgasket goes, the coolant can leak into the cylinders through the cracks of a blown headgasket

 

The car does not smoke at all. Where would I find that UV dye? If it were the head gasket wouldn't it push coolant out under boost? If water can seep into the cylinders then boost pressure would also leak out into the cooling system but it does not push any out.

 

Any auto parts store carries it. Autozone etc.

If you go to autozone it is sometimes mixed in with their AC stuff.

You could just be emptying the coolant reservoir when the engine gets really warm. Drive it hard, and the hot coolant will expand enough to come out the reservoir, then as the engine cools off the coolant will be drawn back into the radiator and the res will be empty.

My reservoir is empty, but I don't have a blow HG.

 

do a leak down test. fill your radiator up to the top and see if you get any bubbles while you're pressurizing the cylinder