Spending a galon of Antifreez in a week

[locopr31]

Hello Everyone:

I need an advice, I have a 1999 c280 sport. On a weekly basis I am putting about a gallon of anti-freeze. I Mechanic that I know did a test to see if the head gasket was bad and the test came negative. What else could I check to find out why the antifreeze is running out.

[manny]

Has your mechanic done a complete pressure test on the cooling system ?
If the headgasket is indeed okay, the coolant has to be going somewhere.
It may help to remove the plastictray under the engine compartment & look for visible traces of coolant. ;)

[Ashkan's C280]

little off topic, but I use to run a 50/50 and i checked my amount left yesterday, not too much gone but I added a thing of water wetter, it did not seem to really have an effect, I let the engine run with the cap off as said before, not sure if I needed to though

[Renn 208]

If you're losing water, do not add more anti-freeze. Instead add water until you can find and repair the cause of consumption. It's the water that keeps your engine cool, and if you keep dumping in anti-freeze your mixture will not do you any good.