Reader Question: I have a 1997 Jeep wrangler 2.4L engine. Engine is rebuilt new thermostat, new radiator new hoses. There is no water in oil, no white smoke, no apparent leaking of coolant or water out the tail pipe.
I have not found any leaks of any sort anywhere on the ground, but I must regularly top of the radiator with coolant, and just returning from a 600-mile trip I had to put a gallon of coolant in the radiator. The engine keeps a constant temperature of 180 and it has not yet over heated.
Do you have any idea of what this could be?
I would HIGHLY recommend you get a cooling system pressure test done at your local mechanic. Just about any mechanic can do this simple and inexpensive pressure test to determine where the leak is. If you added a gallon of coolant within 600 miles, I would assume you have a small external seep somewhere in a gasket, hose or water pump.
There is a possibility of a very small head gasket leak. But since you do not have any of the signs of an internal leak, I have got my fingers crossed that it is a simple external leak. Make sure they also test the radiator cap for leaks!
If the pressure test does confirm an internal leak though, I would recommend you try a can of K&W Engine Block Sealer additive you can buy at most auto parts stores and follow my instructions on this page and not what is written on the can.