The air supply system for engines with a selective catalytic converter system consists of the following components:

- air filter;

- intake air duct;

- turbocharger;

- charge air pipeline;

- charge air cooler;

- heater of the intake system.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Intake system resistance test

Install a vacuum or water pressure gauge in the intake air duct.

The pressure gauge adapter must be installed perpendicular to the air flow in the straight section of the duct, at a distance of one duct diameter from the turbocharger.

Note: On many automotive engines, intake resistance can be measured by removing the mechanical clogging indicator and replacing it with a vacuum or water gauge.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Run the engine at maximum fuel supply, maximum load and rated speed.

Take the reading on the pressure gauge.

Maximum resistance of inlet systems 635 mm water column

Проверка системы впуска и турбонаддува Cummins ISF3.8

If the resistance is higher than normal:

- Replace or clean the air filter.

- Check the air intake duct for damage.

Turbocharging system

Preliminary checks

Check the pipe connecting the compressor and the charge air aftercooler for breaks.

Note: when using low-quality pipes, they may rupture when the maximum boost pressure is reached (for example, when driving on a highway at a speed close to maximum, when driving uphill or when overtaking).

Drivers of GAZ "Valdai" cars of early years of production especially suffer from this malfunction.

In addition, the branch pipe of these cars has a complex shape and it is not always possible to find it on sale.

As a compromise, dealers suggest lowering boost pressure, but at the same time losing power.

Some owners solved the problem drastically by installing a homemade metal adapter on the pipe, which reduced its diameter, which made it possible to install a more durable hose that has the same dimensions at both ends.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Attention: movement with a torn branch pipe causes dirty air to suck in, which will lead to a quick failure of the turbine and the cylinder-piston group.

Remove the air intake duct and air intake manifold from the turbocharger.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Check compressor blades for damage.

Replace the turbocharger if damaged.

If the compressor impeller is damaged, check the air intake duct and filter element for damage.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Repair all damage before starting the engine.

Remove the outlet from the turbocharger outlet.

Check the turbine wheel for damage.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Check the turbocharger wastegate control mechanism.

Check the lever pin.

Replace the turbocharger if the lever pin is worn beyond the limit.

Проверка системы впуска и турбонаддува Cummins ISF3.8Проверка системы впуска и турбонаддува Cummins ISF3.8

Check the valve and valve seat for cracks or erosion.

Replace the turbocharger if necessary.

Move the lever by hand to check the freedom of rotation of its axis.

Check for excessive play between axle and bushing.

Replace the turbocharger if axle and bushing are damaged or jammed.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Check the turbocharger wastegate actuator.

Check the axial clearance of the turbocharger axle.

Install the dial gauge on the turbocharger axle.

Drown the axle.

Set the indicator to zero.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Move the axle to the indicator tab and determine the axial clearance.

Axial clearance 0.001 - 0076 mm

Проверка системы впуска и турбонаддува Cummins ISF3.8

Check the radial clearance of the turbocharger axle bearing.

Gently press the compressor wheel against the housing and dipstick.

Проверка системы впуска и турбонаддува Cummins ISF3.8Проверка системы впуска и турбонаддува Cummins ISF3.8

Record the amount of clearance.

While holding the dipstick in the same position, move the compressor wheel away from the housing and re-measure the gap between them.

Subtract the smaller amount of the gap from the larger one. The result obtained is the radial clearance of the bearing.

Radial clearance 0.396 - 0.602 mm

Repeat these steps for the turbine impeller.

Replace the turbocharger if the bearing radial clearance is not correct.

Check the turbocharger compressor inlet and outlet for oil.

If oil is found in both passages, check for an oil source upstream of the turbocharger.

Note:

- The presence of traces of oil at the compressor inlet is allowed for engines with a closed crankcase ventilation system, in which the crankcase cavity communicates with the intake air duct.

- After a turbocharger failure or in other cases when oil or foreign particles enter the charge air system, it must be checked and cleaned.

Проверка системы впуска и турбонаддува Cummins ISF3.8

If deposits and / or oil drips are found only in the outlet, install the air inlet and charge air cooler lines to check the resistance of the intake system.

Check the resistance of the intake system.

If there is no resistance in the inlet, replace the turbocharger.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Leak test

Add fluorescent dye (no. ЗЗ76891) to engine oil at the rate of one dose per 38 liters of oil.

Note: The fluorescent dye is supplied in 118 ml plastic bottles.

Let the engine run at low idle speed for 10 minutes.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Turn off the engine.

Let the turbocharger cool down.

Remove the outlet pipe from the turbocharger outlet fitting.

Remove the outlet of the exhaust system.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Using a high intensity heat lamp, check the turbine outlet for oil.

A dark blue light indicates the presence of fuel in the oil, while a yellow light indicates an oil leak.

Проверка системы впуска и турбонаддува Cummins ISF3.8

If oil is found in the turbine housing, remove the oil drain line and check if it is clogged.

If you find a blockage, remove it.

Install the return line with new O-rings to the cylinder block.

Проверка системы впуска и турбонаддува Cummins ISF3.8

If there is no blockage in the drain line, remove the turbocharger.

Using a high intensity heat lamp, check the turbine outlet for oil.

A yellow glow indicates an oil leak from the engine.

In the case of a yellow light, the turbocharger can be reinstalled and continued to operate.

A thin layer of oil on the housing and the turbine impeller need not be removed, as it will burn itself out during engine operation.

All oily deposits in the turbine housing must be removed before installation with a clean cloth.

If no yellow glow is found at the turbine inlet, replace the turbocharger.

Проверка системы впуска и турбонаддува Cummins ISF3.8

Install the outlet manifold outlet.

Install the outlet pipe to the outlet fitting of the turbocharger.

Install the inlet pipe to the turbocharger compressor inlet.