I am amazed at how much I learn about recreational vehicles on a regular basis. I'm a car guy and I consider myself to be a pretty good mechanic. I spent years cranking wrenches on aircraft as a licensed airframe and power plant mechanic. RV's are a whole different animal though and require a different skill set to keep them running. Most frustrating to me are the systems that require a trained technician to repair and service them. I could have saved thousands if I just knew something about air conditioning and electronics. On top of that, getting a trained service person to work on a RV is difficult, at best. Recently we had an engine overheat and burn up when a radiator hose blew; most likely due to age. I have owned a ton of vehicles and never replaced a radiator hose. As I have painfully learned and repeatedly stated in this blog; do yourself a favor and have your hoses inspected and/or replaced regularly. That includes you folks with tow vehicles. Now we are again experiencing overheating and I have revisited the whole rear engine motorhome cooling system. Most pushers are diesel and turbocharged. That means they have both a radiator and a charge air cooler-the radiator cools the engine and the charge air cooler cools the turbo. Two main things conspire to destroy the efficiency of both those coolers. Until recently diesels ventilated their crankcase via a tube, called a slobber tube. Gasoline and newer diesel engines use a PCV valve that recirculates this oily mixture. That oily mixture emanating from the slobber tube blows right into the radiator and the fan loves to help embed it. Additionally dust, mud and road grime find their way up there, also with the fan's help. The cure for the first problem is to lengthen the slobber tube by adding a little length with some durable, high temp hose. To help with both problems, Freightliner recommends spraying down the radiator with Simple Green and then washing it down thoroughly. We have also used Dawn mixed with water with a lot of success-we use a small garden sprayer to apply it, You should gain access to the unexposed side of the radiator and do that side also. How often depends on the conditions you are encountering. By the way, every source I looked at says stay away from pressure washers as it can damage the radiator. I also have been told the pros at most Freightliner facilities have a purpose built pit where they can get to the radiator and steam clean it. It's supposed to do wonders. By the way, the industries solution to rear radiator clogging was to put the radiators in the side(s) of the motorhome. Early models had difficulty getting proper airflow and engine overheating was prevalent, so keep that in mind if you're contemplating buying one. Finally, I hope I raised some awareness about keeping your radiator clean so you (and your engine) can keep it cool.