I had a problem the other day and my engine got very hot (the needle was at the H) Due to low coolant. That problem is a leak I cannot find, the engine oil is clear and the exhaust isnt white so I do not know where this coolant is going. I had a bit of red sludge near the radiator cap, but, it hasnt reappeared. The coil pack is now ticking VERY loudly and my engine is sputtering and missing. This only happens when the engine gets to operating temperature. Is this normal? No spark plug wires are loose and the spark plugs are tight.