Ian, either oil pump is covered under the diesel engine warranty for 5 years or 100,00 miles. I do not believe that the Ford ambulance prep package has any affect on the warranty what so ever - unless you make an ambulance out of a vehicle without the ambulance prep package. /ubbthreads/images/graemlins/eek.gif Personally, I would be more concerned with the repeat failure of the pump and what is causing the pumps to fail. Do you know if this is the engine oil supply pump or the high pressure oil pump (HPOP)?
