solomed

I have a 2004 SL 55 AMG with a mysterious coolant leak. I got a "coolant low" warning light last Tuesday and got home and poured in 2 quarts of coolant. Few days later was low again. No coolant under the car, inside floor mats. Looked at dipstick and no coolant looked like it was there and the oil level dipstick was the same at 150. No coolant in any part of the engine compartment. Car has been running great with no white smoke out of exhaust and oil looking clean as can be from dipstick. After filling it up again I didn't drive the car for 3 days and was 1/4 inch low again just standing still! Again oil level was rock steady. So total coolant in over 1.5 weeks is 3/4 gallon and I can't find any anywjere. Anyone have any ideas?

busaboy

In general that would be a pretty big leak unless the outside temperature was hot and you drove a large number of miles. A pinhole leak in a hose or a deteriorating hose interface at the clamp can vent steam at a fairly large rate. Unfortunately you need to start tearing things apart top and bottom and try to find the telltale clues of a leak in a hose, overflow tank, heater core, multitude of heat exchangers or radiator. Look for scale and drips.

If you have a head gasket problem you need to stop driving ASAP. You may want to pop a valve cover to see if there is foam.

If you lost your inter-cooler under the supercharger you also need to stop driving ASAP.