The Positive Crankcase Ventilation (PCV) system decreases the amount of hydrocarbon emissions since blow-by gases and crankcase vapors are channeled in the intake manifold and mix with intake air and then drawn into the combustion chamber to burn together with the air/fuel mixture. It is a system through which fresh air from the air filter housing is pumped through hoses into the crankcase :where the fresh air then mixes with blow-by gases before being drawn out by intake vacuum through the PCV valve into the intake manifold. High intake manifold vacuum during idle and part throttle helps draw blow-by gases and crankcase fumes through the PCV valve and the ventilation hose into the intake manifold while the fresh air is drawn from the air intake duct or filter housing into the crank case. Unlike the PCV valve or the system hoses, these may experience decline in efficiency due to sludge buildup, and as a result, crankcase vapors will not be expelled, hence pressure build up and resulting to crankshaft seal leaks, in a case where seals are leaking. One should check the PCV hoses during an oil filter change, air filter change, fuel filter change, or spark plug change; if the hoses are clogged they needs to be cleaned and if cracked, torn, or deteriorated they need to be replaced.