a compound pressure gauge 131 a moisture indicator 132 a safety pressure relief valve 133 which may for example be set at 1 3 psi and a safety vacuum relief valve 134 which may for example be set at 1 3 psi also connected to the air filter 101 is the inlet duct 102 having a valve 115 which may be solenoid or diaphragm operated in operation when the engine is off the valve 115 closes other engine openings such as the oil dip stick hole are also sealed in the manner which is now generally utilized the three way valve 114 moves to allow fluid communication between the desiccant in the container 116 and the intake manifold so that the region above the pistons is kept dry when the engine is turned on the three way valve 114 connects the desicant filled container 116 to ambient and the heat from the adjoining exhaust manifold causes water to be driven from the desiccant and out to the ambient concurrently with the movement of the three way valve 114 the valve 115 opens to allow passage of air in through the duct 102 to the air cleaner 101 and down to the intake manifold through the carburetor 103 thus normal engine operation is attained as in the embodiments of fig2 4 the variable volume device 120 functions to avoid the addition of contaminated and moisture laden air into the inside of the engine the advantages of the contamination control apparatus in accordance with the invention are numerous the invention virtually eliminates contamination from dust and moisture via air breathing along with the resultant problems whenever the engine is off equipment life is greatly extended and the frequency of oil filter and oil changes will be dramatically reduced once the engine.