Over time, resinous deposits from crankcase gases accumulate in the crankcase ventilation system of the engine, making it difficult to remove these gases into the engine cylinders for combustion

As a result, the gas pressure inside the engine rises and oil leaks through the seals

To avoid this, periodically clean and flush the system

You will need a flat-blade screwdriver.

Cleaning the ZMZ-406 crankcase ventilation systemCleaning the ZMZ-406 crankcase ventilation system

Loosen the clamps and remove the crankcase ventilation and oil separator purge hoses from the pipes of the cylinder head cover.

Cleaning the ZMZ-406 crankcase ventilation system

Loosen the clamps and remove the crankcase breather hose from the throttle body.

Rinse the hoses with gasoline or kerosene, blow with compressed air and dry.

Crankcase ventilation system ZMZ-406 GAZ-2705Crankcase ventilation system ZMZ-406 GAZ-2705

Using a screwdriver, unscrew the six screws securing the oil slinger

Remove the oil deflector

We wash the oil slinger and the cylinder head cover in kerosene. Degrease the mating surfaces and screws securing the oil deflector and valve covers

Apply adhesive sealant to oil deflector

Apply adhesive sealant to the oil deflector

Install the oil deflector in place and press it tightly

We tighten the oil deflector mounting screws, applying anaerobic sealant to their threads.

Clean the hose fittings.

Install all parts in reverse order

The operation of the crankcase ventilation system can be checked as follows: when the engine is running at the minimum crankshaft speed at idle, there should be a vacuum in the crankcase.

This is determined using a water piezometer connected to the engine crankcase through the oil dipstick pipe.

If the system is abnormal, there will be pressure in the crankcase. This is possible in case of coking of ventilation channels or excessive breakthrough of gases into the engine crankcase.