How much cooling?
I recently posted that I thought the diesels were overcooled in this winter weather and that I thought most of the cooling could be blanked off. This seemed to be rather contentious, so I decided to try it. This morning I blanked off the whole of the lower grill, both of the small grills either side of the AR grill and the oil cooler port. This left just the intercooler air, the AR grill air and the port at the front of the undertray to cool the engine.
Conditions: moderate frost overnight. Air temperature 5 degrees during drive. Sunny.
Initial results: Warm up, on slow roads, was quicker, but not dramatically so, about 10 minutes to reach 50 degrees instead of perhaps 15. The engine then ran in the middle to top end of the thermostat range, instead of right at the bottom end, reaching but not exceeding 90 degrees. After half an hour at 70 mph the oil was at about 60 degrees (measured on the filter), what I could reach of the metalwork behind the engine was touchable so the alternator and power steering should be ok. The gearbox is hard to get to, but at 2000 rpm cruise it should be ok. The turbocharger has the AR grill air so it should be ok.
Worth bothering with? Too early to tell, a faster warm up and hotter running may benifit economy, I'll have to try it on a long run to test that and the final oil temperature. It doesn't make much difference to how fast I get warm, but combined with a 'hedghog' coolant heater it might.
In the mean time the front of my car is covered in gaffa tape - so it's coming off!
Two notes of caution: Flat and crowded Essex roads mean I get 51 mpg on the trip computer. If you get less you will need more cooling. I haven't tried it in slow, stop start traffic yet, but would not expect trouble there.