adding oil cooler to D2 stationary engine

I would put supply to the bottom and add a bleeder valve above the top. I would also install a good quality ball valve on the return line at the top top to choke it down a wee bit as necessary to insure it fills completely with oil and pushes all the air out the bleeder. Once full open the valve completely.

That was my first thought, Old Iron. Could there be some problem with pushing the flow up from the bottom with an air bleeder at the top of the system? Is there some reason why Cat ran the flow downward? Am I giving this a lot more thought than necessary?

At this point I'm going with Old Iron Habit's idea, except for the valve in the return line. I guess the relief valve built into the system would prevent a catastrophy if the valve wasn't opened, but the D2 oil pump is bigger than some tractor hydraulic pumps. Could it possibly fail to push an air bubble through? Isn't there some of this air bubble effect every time you change oil anyway? On some engines it's impossible to prefill the filter.

No big mystery. Just duplicate Cat's oil cooler arrangement.

Let me know how that works out!
If you had said finned tubes, I would have thought 3 as plenty but not so sure you'll get the temperature drop you are looking for? Any chance you can get a Thermocouple down in the crankcase oil? Before and after would have been nice but any data is better than no data!

Here's a couple pics of the cooler. I made a mistake. I settled on four tubes, not three. They are about 16 in long and are soldered into all of the fins. The little tin doghouse behind it holds a refridgeration condenser fan, about 1/10 HP. There's a bunch of heat radiation area in this thing, but no upper or lower tanks. I'm now trying to make up my mind before I buy the other hose. Check out the ag hydraulic/NPT line adaptors of my own design. I couldn't find any of them either, had to make them.

It takes the same pressue to push all the tubes full from the bottom as it takes to push the oil to the top and let it run down. (learned this in concreting pumping 101 when we switched to pumping bridge and building columns from the bottom via a port.) My thought on pushing from the bottom fills the entire cooler insuring you are getting the max out of your cooler.

OH! If there are fins and 4 tubes, it ought to dissipate a lot of heat! Still like to see T/C measurements.

I'll know a lot about temp drop after a day of running just by the red-hand test! Quickest way to get oil temp is to put a was of insulation on an oil pipe and stick Momma Bear's cooking thermometer under it, against the tube. Trouble is, I didn't bother to go past the red-hand test before I installed the cooler.

Old-iron-habit, I wasn't so concerned about pressure so much as trapped air in the top of the system. Maybe that's not a problem;maybe the top air bleeder on D2 is more for draining the cooler than for bleeding the air out???

Hi Jack,
according to the U D4 & D6 OMI's the oil cooler (Vent Valve in Cat speak) bleed screw is indeed for more rapidly draining the oil from the cooler when changing the engine oil.
Your rig has come a long way since Day 1 on here. Especially after getting some true reading gauges on the sparking department output wires.
Keep at it.
Eddie B.