Do not start or run an engine without coolant, as the water pump seal could be damaged.
Water pumps fail for a variety of reasons. The water pump seal is cooled and lubricated by the engine coolant. If the engine is operated with a low coolant level and/or a leaking radiator cap not only could premature water pump failure occur, if overheated there is a risk of damaging the cylinder head gasket and warping the cylinder head and engine block deck surfaces. Because the camshaft is installed in the cylinder head, a warped cylinder head may be rendered useless if the warpage effects the alignment of the camshaft journals.
Never open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.
When performing repairs to the cooling system, apply a light coating of an anti-seizing compound to the following items:
All cooling system O-rings
All cooling system rubber seals
Any threaded fastener installed into the engine block or cylinder head