16. Crankcase Pressure Test

16. CRANKCASE PRESSURE TEST

Purpose:
The purpose of this test is to measure the crankcase pressure. Crankcase pressure is a measure of how well the cylinders are sealing.

Crankcase Pressure Test
- Measure the pressure at the oil fill tube with Adapter, Crankcase Pressure Test 303-758, with the engine at 70°C (158°F) minimum.
- Block the breather tube.
- Measure with no load at 3,000 RPM.







If greater than 10 in-H20, refer to the Engine, Engine - 6.4L Diesel, General Procedures, Compression Test to continue diagnosis.







Recommended Procedure:

NOTE: Do not plug hole on Adapter, Crankcase Pressure Test 303-758.

Make sure the engine is at operating temperature. A cold engine gives higher readings. Remove the breather tube from the air cleaner tube. Block both ends of the breather tube with the caps provided in DSL ENG Pressure Test kit 014-00761 or equivalent.

Install the Adapter, Crankcase Pressure Test 303-758 in the oil fill cap hole. Plumb to the Magnehelic Gauge(R) in the gauge block. Make sure the Magnehelic Gauge� has been zeroed.

Start the engine and operate at 3,000 RPM. Hold for 30 seconds minimum and take a stabilized reading. Do not block the hole at the top of the restriction tool.

Possible Causes:
- Broken or worn compression rings
- Polished cylinder bores
- Leaking or bent valves

Inspect the intake air system. If the intake air system allows dirt to enter the cylinders, it will quickly dust the engine causing high crankcase pressure.

Tools Required:
- Adapter, Crankcase Pressure Test 303-758 or equivalent
- Magnehelic Gauge(R) (part of DSL ENG Pressure Test Kit 014-00761)
- Protective screen
- Hose
- Screw clamps