Does the fitting of a diff guard to the front axle make it run hotter?
reason I ask is that when my motor is cold there are no clonks from the front.  when it gets hot - hey presto a bit of a light clonk/backlash appears, nothing too heavy.  so i put it down to the oil thining.
my front diff guard is the clamp-around-the-pan type - and I have noticed that it is full of mud - therefore prevent the cooling of the bottom half of the diff pan where the oil sits. 
I havent cleaned it out yet, but plan to do so today. 
what do you think - could i be right?