Where would coolant be leaking from if hoses are ok?

Answer 1

Aside from broken hoses, coolant leaks may occur in the radiator, water pump, thermostat housing, overflow tank, freeze plugs (in block), the head gasket (into combustion chamber(s) and/or crankcase) or simply a cracked block. An old radiator or blown water pump seal are the most common or frequent source(s) of coolant leaks after hoses. Placing a white sheet of paper (or even newsprint) under your engine overnight may help locate the source of a leak. Coolant is green. Otherwise, be certain that you have inspected ALL hoses. Coolant hoses on some automobiles or light trucks may be located under or behind other components and not visually obvious at first glance, especially toward the rear of the motor. Also, be sure that all hose fittings are tight. Check the thermostat housing gasket, too. This is a domed fitting on top of the motor where a radiator hose attaches. Don't forget the overflow tank, clear plastic typically mounted to fender wall. The water pump is belt driven, typically located at the "front" of the engine and may have a radiator fan mounted to it (as opposed to an electric radiator fan which will be mounted to the radiator itself). Inspect the water pump shaft and housing behind the pulley for signs of leakage. Typically there will be a tiny (3mm) "weep" hole to indicate a failed seal. If the bearing goes, fluid may leak out around the shaft. It will also sound like marbles in a can. Visually inspect the radiator for corrosion which may form around cracks, especially on the radiator passages between the rows of cooling fins and where those passages join the side tanks, as well as where the intake/outflow pipe fittings join the side tanks. There is also a drain plug that is typically threaded. Make sure it is tight and not leaking. If nothing is apparent, run the engine to operating temperature (HOT) and look for small wisps of steam, bubbles or dribbles around the radiator. If the radiator appears clean and dry... Locate the freeze plugs in your engine block which may have been dislodged. There are typically (3) located along the lower sides and one in the front and rear each. Finally, check the engine oil dipstick for a frothy milkshake appearance from coolant mixing with engine oil which would indicate a leaking head gasket. This will be most obvious when the engine has been sitting overnight. If the engine has been running, the oil may appear "smeared" with bright colored streaks on the dipstick. If this is the case, have your engine serviced ASAP as coolant in the engine oil is very dangerous for the engine. Good luck.