Category Archives: Cummins 4BT

Preparatory Step: • Remove the drive belt. NOTE: Removal is easier if the crankshaft pulley is loosened before removing the belt. 15 mm Remove the crankshaft pulley. 10 mm Remove the front cover.  

17 mm Drain the lubricating oil. NOTE: Use a container that can hold at least 20 litres [15 U.S. qts.] of lubricating oil. 10 mm Remove the lubricating oil pan. 10 mm Remove the lubricating oil suction tube. Inspect the suction tube for cracks. Clean the gasket surfaces. 10 mm Install the lubricating oil suction… Read More »

Preparatory Step: • Drain the coolant. 90-95 mm Remove the lubricating oil filter. Clean around the lubricating oil cooler cover. 16 mm, 19 mm Disconnect the turbocharger supply line. 10 mm Remove the lubricating oil cooler cover, gaskets and cooler element. Clean the sealing surfaces. Pressure test the element to check for leaks. If leaks… Read More »

Disassembly Thoroughly clean the area around the pressure regulator plug to prevent debris from falling into the plunger bore when the plug is removed. 19 mm Remove the threaded plug, spring and plunger. Service Tip: The plunger normally can be removed by inserting one finger into the plunger bore until snug and pulling up. If… Read More »

Various gaskets, seals and plugs are used to contain the lubricating oil. Most leaks can be identified during routine inspection of the engine and vehicle. A blown expansion plug can allow a relatively large quantity of lubricating oil to escape resulting in a sudden drop in the lubricating oil pressure. When checking for such a… Read More »

Fuel dilution is limited to five sources: 1. Injection pump shaft seal 2. Fuel leaking by the rings 3. Fuel Transfer pump 4. A crack in the cylinder head from the fuel filter location to the air intake 5. Injector leakage Use the following logic to determine the source of the oil dilution with fuel:… Read More »

Since the lubricating oil cooler design does not require gaskets or seals to maintain the separation of oil and coolant, the element itself must leak to allow mixing of the fluids (refer to page 2-18 for the replacement and oil cooler testing procedures). During operation, the lubricating oil pressure will be higher than coolant pressure.… Read More »

Caution: Diluted oil can cause severe engine damage. Check the condition of the lubricating oil. • Thin, black lubricating oil is an indication of fuel in the oil. • Milky discoloration is an indication of coolant in the lubricating oil. Coolant in the oil can be caused by: • Expansion plugs leaking. • Lubricating oil… Read More »

Low lubricating oil pressure (or no oil pressure) can be caused by several lubrication system related malfunc­tions. To begin the investigation, determine the engine operating conditions when the low pressure was first ob­served; i.e. following a service interval, at idle only, while operating on a steep grade, etc. Lubricating Oil Level High oil level can… Read More »

High oil pressure usually occurs after the engine is first started in cold weather. Cold start oil pressure typically will be approximately 552-689 kPa [80-100 psi]. If the pressure regulator plunger is operating properly the oil pressure should drop back to approximately of 449 kPa [65 psi] when normal operating temperature is reached. Lubricating Oil… Read More »