Fuel addition to warm engine??

[akghound]

We are using coolant heat exchangers to pre-heat wash water for pressure washers on trucks. During cold weather these cool the engine to the point that the thermostate never opens. The mechanic tells me that when the coolant drops to somewhere below 130* the on board computer adds fuel to warm up the engine. The engine is set to run at 1000 RPM while washing, to power the pump via PTO. My question is how does the computer add fuel without increasing RPM. These are International 366 engines. I claim he is mistaken. It does add fuel at an idle at lower temps, thus increasing RPM but at 1000 RPM I doubt that any additional fuel is added to warm the engine. Can anyone please weigh in on this discussion? Thanks .... Ken Gardner

[Lead Head]

With a diesel, you cannot add more fuel without increasing power/speed. 130*F is far too cold to have the engines working (either driving, or sitting there running a PTO). I'd invest in some kind of insulation wrap to go around the water tanks.