oil leaks around timing chain cover and the valves rattle at 1500-2300 rpm. can also smell just a hint of anti-freeze.
oil leak around timing cover on 2002 Nissan Maxima
If you are loosing coolant have the cooling system pressurized to look for leaks and repair as necessary. Check the condition of the radiator, cap and hoses. Clean the engine and run the engine to determine where the oil leak is coming from if it low down near the crankshaft pulley it may be the crank pulley seal. The valves are hydraulically self adjusting so good oil and frequent oil changes are necessary.