We have a 2004 Dodge Sprinter 2500 Van 5 Cylinder Mercedes Turbo Diesel. Recently, at around 70,000 miles, when we start the engine block heater, the sounds are not normal. The heater appears to start working, since we can hear and smell the burner, but the heating ceases within a few minutes. The unusual sounds continue until the heater is turned off.
So… What does it sound like?
It has a diesel fired coolant heater, sounds like a miniature jet engine. Perhaps the electric pump has failed. Feel the hoses, check if they are all getting hot. If the hoses are only hot near the heater there is no circulation.