The feature than can determine the way the pump turns would be whether they were driven by the smooth side of a serpentine belt on the one had, vs. the grooved side of a serpentine belt or a V belt on the other hand.
It would really be a good idea to get a numeric reading on the engine temperature...
Of course, the number one issue is the thermostat. If it is too high of a range, or is not opening properly, the 4-core radiator will never be called on.
Next is the possibility that steam/vapor is collecting around the t-stat. I had a big problem with that in an Aries K. Once it got hot enough to open the t-stat a few times the temperature settled down.
If the fan is not doing its job sufficiently you will get overheating at stop lights and in crawling traffic, but cooling that is fine above maybe 15 or 20 MPH.
If the bottom radiator hose has failed, it can collapse due to the suction of the water pump. For the whole length of that hose you should not be able to flatten the hose by hand. It should have a spiral of wire, a "spring," inside it that prevents that. If that wire has corroded, and isn't doing its job you can get compromised flow.
When the engine is cold, start it up. Before long, the heater hose that comes out neat the t-stat should start to warm up, while the upper radiator hose stays cold. The closed t-stat forces circulation through the heater system. This causes flow over the hot surfaces, and carries the heat from the area of the cylinders to the area of the t-stat. without that, the water's heat would take 10's of minuted to get to the t-stat.
Next, when the heater hoses get too hot to touch comfortably, but before the engine overheats, the upper radiator hose should start to warm up. The t-stat will start to open, and a little hot water will sneak out of the engine, heating the hose a little. That will introduce a little cold water from the radiator into the water pump, where it will get quickly mixed with the water circulating through the heater system, closing the t-stat pretty quickly. So the initial warming of the upper radiator hose will be pretty slow.
If it overheats before the upper hose gets too hot to touch, you have a t-stat problem. Either the t-stat is failing to do its job, or it is not getting the heat signal it needs to operate properly.
If the heater system is clogged or plumbed wrong, it will not allow the requisite circulation.
I hope this gets you on the road to fixing your overheating problem. A 302 with a mondo radiator as you describe should have no overheating troubles, even in the desert!
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Brian, The reason why I asked this question is because I put this engine in a 1988 Ranger pickup and I have always run on the very warm side. I heard that some of the 302's water pumps turn in the opposite direction. I put a 4 core radiator that I purchased from James Duff Ent. in the truck and it still runs warm. I have a gauge that reads temp but not in number format, (standard ranger). I just have not been able to figure it out??????????????
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