Well I have cancelled the appointment with the bank for the loan to buy a new core (I got two prices from a local supplier, one very reasonable at $3600 for a locally made custom one and the other @ nearly $8600 for them to import and supply a genuine Cat core which surprisingly is $2000 more then one from the local Cat dealer.
I pressure washed the core with a little dinky Karcher K2 pressure washer. It is a freaking awesome little bit of gear and stupidly cheap and if it is worth anything I can recommend it. I also tightened the belts, and just installed the air deflector with no radiator guard as I am not doing anything that should damage the radiator unless I go full retard.
Dramatic difference in temps and I did not get the radiator spotless as I ran out of water as I only had 40 litres. Engine was running half to three quarters into the green, and converter was slightly cooler as well about half into the green. It was not hot hot this afternoon. The dozer itself ran like a champion. Quick and snappy gear changes. Not sure if I had positive bias going on as I could see it was not getting hot or it was running better
My only issue now is grass trash getting sucked on and plastered over the radiator. I do have engine guards for the machine that I took off for better airflow. I remember an old contractor we got at times that ran a late model 10K D6C and his machine had covers over the engine that extended up so there was probably only about a 10" gap between bonnet and this guard he had. I have seen D8H's that had full length fenders as well, not that I am doing that.
Other question is are Cat belts worth it? $281 for a set of three (not sure why three as it only uses two) They are only CX section belts. I can get them elsewhere.
One thing that could be done is for improved cooling capacity, install a full width core) the tanks are built for a full width core but 4" on one end is not blanked off for the air portion of the converter cooler. Then you could get a generic oil cooler from somewhere else and mount it somewhere, cooled by electric fans. Not going to be doing that, but it would be possible to improve the cooling capacity.
I know the air deflector looks rough as guts. I did a quick hash job just for proof of concept. It certainly works.