these radiators are made of plastic and aluminum.the aluminum tubes will shrink over time and temperature cycles and the tubes will not flow enough coolant.[6-9yrs]diesels also run cooler than gas engines [the higher the compression the less waste heat] so if you are getting hot you have a big problem not a small one.water pumps can only leak to cause a problem with the exception of a couple of bmw's that had a plastic impeller. david poole european performance dallas tx.