Fuel system
Why is diesel entering the engine oil?
Diesel odor, thin oil and a rising level require finding the fuel's path into the crankcase. Directions: injector fault, frequent/failed DPF regeneration, injector seals/copper sleeves, head fuel galleries or cracks, driven fuel pump or its seal.
Injector overdelivery or poor atomization
Unburned fuel can wash the oil film from the cylinder and reach the crankcase. Clues: increased consumption, smoke, rough running, rising level, diesel smell and one injector differing in correction or cutout response.
DPF regeneration
Where late additional in-cylinder injection raises exhaust temperature, some fuel may enter oil. Risk increases with frequent/interrupted regeneration, a heavily loaded DPF, prolonged low-load work and sensor/temperature faults. Investigate rising level and DPF trouble together.
Copper injector sleeves
On engines with separate sleeves in the head, damage, corrosion or seal faults may admit fuel into oil. This particularly matters where the fuel system passes through the head.
Fuel galleries in the head
On some engines, including unit-injector systems, head cracks, gallery defects or injector seals can allow contamination. Replacing the injector alone may not change anything.
Fuel pump and drive
On certain engines, failure of an internal mechanical/driven pump seal lets diesel enter the crankcase. Checks depend on the specific construction.
What to observe
Rate of level increase, diesel smell, thinning, DPF problems/frequent regeneration, smoke, rough running and injector faults.
Related problems
Further service support
Have a fault code?
Problem still there?
If these checks have not identified the cause or the fault returns, contact TSV Servis. The more initial information you provide, the sooner we can identify the next diagnostic direction.
What to send us
Engine model, S/N, level increase per operating hours, DPF condition, injector corrections/tests, cylinder-head design and fuel-system test results.
Include the make and model, S/N or a nameplate photo, engine model if known, operating hours, exact code or display photo and when the fault occurs.
Also tell us what you have already checked or replaced and the results. Include a photo or short video of the symptom where useful.
+420 722 307 850 · tsvcz@seznam.cz