The cam gear removal tool we use requires that you slide the cam forward enough to install the puller, so it's damn near like doing all the work to remove the cam, minus pulling the radiator. Installing the cam gear with the cam in the engine is a pain in the ass to boot. So, if it's a major undertaking to remove the radiator from the excavator, it might be worth looking into. Otherwise, I'd recommend just getting the radiator out of the way.
If you can find the crack, and get it really clean, there's always epoxy. I don't adivse that as you'll eventually need to fix it right. The housing could be cracked due to several reasons. Among those, the most likely are
-Loose bolts in gear housing
-Dowell pin came out
-Air compressor/hyd. pump came loose and stressed the housing.
I'd just bite the bullet and tear it apart.