My Jeep has been losing coolant before and after replacing a leaky radiator. block test proved positive for combustion gases but the dealer doesn't find an issue with leak down test. there is not coolant in the oil and vice versa. Does anyone know what this might mean? service manager said he's getting his 'engine guy' to look into it. he thinks they will find a warped piston head. If that were the case, wouldn't that show up with a leak down test? I'm still under the 100,000 warranty so that's good. Thanks in advance.