Detroit Diesel Troubleshooting Diagrams

To determine if an obstructed or damaged breather is causing excessive crankcase pressure, perform the following: ‪

Perform a crankcase pressure test.

If the engine crankcase pressure is less than 3 in. H 2 O (0.75 kPa), check the air compressor.
If the engine crankcase pressure is greater than 3 in. H 2 O (0.75 kPa), replace wire mesh element.

Rocker Cover Breather Resolution

Perform the following steps to replace wire mesh element replacement: ‪

1. Remove the valve rocker cover(s);
2. Remove the wire mesh form the rocker cover;
3. Install a new wire mesh element to the rocker cover;
4. Install the rocker cover to the engine;
5. Verify replacement of wire mesh element;

To determine if a defective air compressor is causing excessive crankcase pressure, perform the following: ‪

1. Perform a crankcase pressure test and record the test results.
2. Disconnect the air outlet line from the air compressor;

3. Repeat step and record the test results.
4. Compare the results of test one with test two.

If the engine crankcase pressure remained the same, check the turbocharger;
If the engine crankcase pressure decreased, repair the air compressor;

The oil pressure regulator valve consists of a valve body, a hollow, piston-type valve, a spring, a spring seat and a pin to retain the valve assembly within the valve body.

The valve is held on its seat by the spring, which is compressed by the pin in back of the spring seat. The entire assembly is bolted to the lower flange of the cylinder block and sealed against leaks by a gasket between the block and valve body. When conditions are such that the oil pressure at the valve exceeds 310 kPa (45 lb/in. ² ), the valve begins to be forced from its seat and oil from the engine gallery is bypassed to the engine oil pan. Thus, stable lubricating oil pressure is maintained at all times. ‪