G3304 and G3306 Engines Caterpillar

The efficiency of the engine and the engine power are reduced if there is restriction in the air inlet and/or the exhaust system.

Inspect the air inlet and exhaust system. Make sure that there are no obstructions or leaks in the system.

Table 1

Tools Needed		Quantity
1U-5470	Engine Pressure Group	1

Illustration 1	g00295554
1U-5470 Engine Pressure Group

The 1U-5470 Engine Pressure Group is used to measure the inlet air restriction and the exhaust back pressure.

Air Inlet Restriction

Air inlet restriction is the difference in pressure between the air lines after the air cleaner and the atmospheric air pressure.

Use the differential pressure gauge of the 1U-5470 Engine Pressure Group in order to measure the air inlet restriction. Connect the pressure port of the differential pressure gauge to the opening for the air filter service indicator on the air cleaner.

For optimum operation, replace the air filter when the air restriction reaches 3 kPa (12 inches of H₂O). The maximum air restriction of the air cleaner is 3.7 kPa (15 inches of H₂O).

Exhaust Restriction

Exhaust restriction (back pressure) is the difference in the pressure between the exhaust at the outlet elbow and the atmospheric air pressure.

In addition to the loss of efficiency and power, excessive exhaust restriction will lead to these results: high engine temperatures, reduced service life of the turbocharger and early problems with inlet and exhaust valves.

Use the differential pressure gauge of the 1U-5470 Engine Pressure Group in order to measure the exhaust back pressure.

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Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.

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Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts. When working on an engine that is running, avoid contact with hot parts and rotating parts.

Connect the pressure port of the differential pressure gauge to the test location on the exhaust manifold. The test location may be located anywhere along the exhaust piping after the turbocharger but before the muffler. Choose a location that is as close to the engine as possible. Install the probe into a straight pipe that is three to five diameters of the pipe away from the last transition.

For naturally aspirated engines, the maximum exhaust back pressure is 3 kPa (12 inches of H₂O).

For turbocharged engines, the maximum exhaust back pressure is 6.7 kPa (27 inches of H₂O).

If the exhaust restriction reaches this limit, determine the cause of the restriction and correct the condition.