3116 and 3126 Truck Engines Problem Engine Has Low Oil Pressure

Probable Cause(s):

* Insufficient Oil
* Defect In Oil Pressure Gauge Or Sending Unit
* Dirty Oil Filter Or Oil Cooler
* Diesel Fuel In Lubrication Oil
* Oil Pump Has A Defect
* Oil Pump Suction Pipe Has A Defect
* Oil Pressure Relief Valves Do Not Close
* O-ring Defective
* Too Much Clearance Between Rocker Arm Shaft And Rocker Arms
* Too Much Clearance Between Camshaft And Camshaft Bearings
* Too Much Clearance Between Crankshaft And Crankshaft Bearings

1. Insufficient oil:

Check oil dipstick for correct level.
2. Defect in oil pressure gauge or sending unit:

Install new gauge or sending unit.
3. Dirty oil filter or oil cooler:

Change oil and oil filter. If problem persists, check the operation of bypass valve for the filter. Clean or install new oil cooler core. Verify that maintenance is done at correct intervals.
4. Diesel fuel in lubrication oil:

Find the place where diesel fuel gets into the lubrication oil. Pressure check the fuel system to check for porosity in the cylinder head or a leaking O-ring seal on an unit injector. Make repairs as needed. Remove the lubrication oil that has diesel fuel in it. Install new oil filter. Fill the engine with clean oil. Refer to Problem 29: Fuel In Lubrication Oil.
5. Oil pump has a defect:

Repair or replace oil pump.
6. Oil pump suction pipe has a defect:

Replacement of pipe is needed.
7. Oil pressure relief valve does not close:

Clean valve and housing. Install new parts as necessary. Check bypass valves in oil cooler and oil filter base.
8. O-ring defective.

Check O-ring in the oil line from the oil pump to the engine.
9. Too much clearance between rocker arm shaft and rocker arms:

Check lubrication in valve compartments. Install new parts as necessary.
10. Too much clearance between camshaft and camshaft bearings:

Install new camshaft and camshaft bearings if necessary.
11. Too much clearance between crankshaft and crankshaft bearings:

Inspect the bearings and make replacement as necessary.

One Reply to “3116 and 3126 Truck Engines Problem Engine Has Low Oil Pressure”

  1. Thanks for the above tips for my 3126 marine engines.
    Want to try cleaning oil sending unit 7E4275, haven’t cleaned it in 8000 hours. Should I attempt cleaning or just replace? What is the cleaning procedure?

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