The investigation is complete and there are some troublesome facts that everyone that owns this type of RV should be aware of.   I will attempt to summarize the findings here.  Our fire was caused by a side mounted radiator that failed and leaked common engine coolant called antifreeze.   You see, antifreeze in most engines is mixed 50/50 with water and is pretty safe in that form.  When a side-radiator diesel pusher RV has a leak the antifreeze is pulled from the radiator by the cooling fan and misted over the hot engine.  The majority of the engine bay configurations have the exhaust and turbocharger on that same side as the radiator and fan assembly so the antifreeze mixture is sprayed directly onto those extremely hot components.  Because of this the water that is contained in antifreeze quickly is flashed off leaving a mixture of alcohol based materials that will easily combust into sustainable flame at 242 degrees.  That kind of heat is apparent in an engine bay of every RV at the exhaust manifold.  Once the Antifreeze ignites it is merely seconds before other hoses are evacuated and flammables such as hydraulic oil, fuel oil and transmission fluid are release to add to the flames.

 

The investigation goes deeply into why the radiator failed but to again summarize allow me explain what happened.  The radiator assembly consists of a transmission cooler, charged air cooler, engine coolant unit and fan assembly.  In side radiator Monaco built Coaches built during 2002 to 2006 had these components are all bolted together.   To make matters worse the fan assembly has a large hydraulically driven fan motor that creates excessive vibration due to a poorly designed fan motor bracket.  We found that our fan bracket as well as many of our friends that have similar coaches was broken from all the vibration.  Others have reported that their fan hydraulic hoses have either failed or have caused dangerous damage to the hoses because of the fan movement due to the fan bracket inadequacies.   All of this stress causes the radiator assembly to fail.   If the radiator leaks and the fan is still able to rotate then antifreeze is sprayed directly onto the turbocharger and exhaust manifold.   A safety point here is don't drive your die radiator RV if the radiator is leaking.