Where is the coolant going?

2001 XK8, 52K miles. Had the system flushed in April. Don't drive with a heavy foot. Don't drive long trips. Don't drive much in extreme heat. Engine doesn't run hot. Even drive with A/C off when top is down. Yet, every month to six weeks, I get a "coolant level low" indicator and, yep, the reservoir is low.

I see no signs of leaks. That is to say, no stains or puddles on the garage floor.

The coolant I've been topping off with is probably at the end of its shelf life.

Could I have a pin hole leak somewhere?

Any other possibilities?

 

COMMON LEAK SIGHTS ON THE CAR ARE AROUND WATER PUMP AREA FROM THERMOSTAT HOUSING AND CROSSOVER PIPE ORINGS, ALSO HEAR HOSES UNDER INTAKE AND THE BIG MATRIX BEHIND THE ENGINE ABOVE THE TRANS BELLHOUSING FOR THE HEATER ALSO, BEST BET IS TO PRESSURE SYSTEM TO FIND THE LEAK, CAUSE IT IS LEAKING IF IT KEEPS GOING DOWN THAT MUCH, OTHERWISE WITH TIME THE RESERVOIR FLOATS SINK AND STICK DOWN

 

Mine shows low level about every 4 months. I just keep topping it off, i can't see any indication of a leak yet. Until it gets more annoying, i'm not going to go fishing for that tiny leak.

 

The plastic thermostat housing is famous for cracks that leak very slowly and never drops a drop on the floor. Look for dried orange (green or some other color) around the base of the housing. Solution is to replace the housing with the aluminum version available from several suppliers on the internet. The aluminum version is less expensive that the OEM plastic one. Consider painting the aluminum unit with a black paint that matches the paint on the plastic one. Replaced mine and wished I had painted it to match. The bright finish jumps out when you open the hood.

 

I'd love to see test point. got a pic of the offending stat housing?

 

Unfortunately, the shiny aluminum housing went to the great wreaking yard in the sky with Black Beauty. Just had the same housing replaced under warranty on the new car and they used the painted black plastic OEM.