Oil pressure sending unit leaks onto a hot engine
Mitsubishi recalled the analogue-gauge trucks of the model year this campaign is recorded against because the oil pressure gauge sending unit, on the right-hand side of the engine, could leak. The recall notice names both consequences: engine damage from the oil that is no longer in the engine, and an engine fire if that oil reaches hot metal. The remedy was a modified sending unit. Two things make this worth writing down four decades later. The first is that an oil leak on the right-hand side of one of these engines has a specific, cheap, known cause worth checking before anything else. The second is that an oil-fed engine-bay fire is exactly the kind of failure this site exists to warn about: if you can smell burning oil, stop and look, and do not keep driving. Have this checked by a qualified mechanic.
Gen 11984–1984USSafety-criticalCommunity consensus
Do not driveNo lo maneje
filteredDoes not fit the vehicle you selected
Provisional matchThis is safety-critical, and the match to your truck is only provisional: it was made on generation, market, year and engine alone. Narrow your selection, and confirm against your own vehicle, before acting on anything here.
Safety notice — Engine.
This affects a safety-critical system. Reference material only: for safety-critical work, consult a qualified mechanic.
Esto afecta un sistema crítico para la seguridad. Material de referencia únicamente: en trabajos críticos para la seguridad, consulte a un mecánico calificado.
Community consensus. This entry is not backed by factory documentation — treat its values and steps as a starting point, not as if they came from the factory manual.
Consenso de la comunidad. Esta entrada no se apoya en documentación de fábrica — tome los valores y los pasos como punto de partida, no como si vinieran del manual de fábrica.
Symptoms
- Wet oil, or an oily crust, on the right-hand side of the engine block
- A hot, sharp burnt-oil smell after a drive, strongest with the hood open
- The dipstick keeps dropping but nothing obvious drips onto the ground overnight
- The oil pressure gauge reads low, high or erratically compared with how it used to read
Likely causes
- The oil pressure gauge sending unit itself is leaking at its body or its threads
- The original sending unit is still fitted because the recall remedy was never carried out on this truck
- Something above the sender is leaking and the oil is simply running down over it
Diagnostic steps
- Degrease the whole area around the sender, run the engine until it is hot, then look at where the first fresh oil appearsPoints toThe oil pressure gauge sending unit itself is leaking at its body or its threadsRules outSomething above the sender is leaking and the oil is simply running down over it
- Follow the oil film upwards from the sender with a light and a mirror, looking for a wet source above itPoints toSomething above the sender is leaking and the oil is simply running down over itRules outThe oil pressure gauge sending unit itself is leaking at its body or its threads
- Ask a dealer whether the campaign named in the source below was completed against this vehicle identification numberPoints toThe original sending unit is still fitted because the recall remedy was never carried out on this truck
Fix paths
Replace the sending unit
$Difficulty 2/5
A sending unit is a small, cheap part and a short job. The recall's own remedy was to fit the modified unit, so a replacement is the answer to both the leak and the original defect at once.
Fix the real leak further up the engine
$–$$Difficulty 3/5
If the oil is arriving from above, replacing the sender changes nothing. Find the actual source first — the sender is often just the lowest wet thing, not the leaking thing.