Diagnose This! – September 2009

Each month in Diagnose This! we present a real-life service scenario with clues as to what the ultimate diagnosis was. If you think you know the answer, be the first to e-mail Dsmith@rrpub.com with the correct response for free Truck Parts & Service merchandise. The answer will be revealed in a future issue of the magazine.

Vehicle: 2005 Sterling
Key components: Mercedes OM926LA engine with exhaust gas recirculation (EGR), Allison automatic transmission
Scenario: The driver complained of oil pouring out of the exhaust manifold on cold startup. The photo shows what the driver saw, and there was a 6-inch diameter puddle of oil on the floor upon startup.
Clues: Power appears OK, smoke emissions were greater than normal, but not severe, and cleared as the engine warmed. Fluid levels are OK and there are no fault codes in memory.