I have a 1939 Ford Pickup with a fresh built 302 (same issue prior to rebuild) and a C4 tranny. Engine issue: The truck runs fantastic BUT when I'm on the fwy for long distances the heat slowly starts climbing and can get to about 230. If I hit traffic or side streets its pretty much always at 190. I am running a 180 thermostat and have a brand new aluminum radiator with electric fan and a shroud. Normally cars overheat when in traffic and my situation is the exact opposite. The faster and more air flow the hotter my engine gets. My thoughts were the water is flowing too fast and not allowing enough time to cool in the radiator? I switched the thermostat to a 190 thinking it would stay shut longer to allow the fluid to sit in the radiator longer but that had the truck getting to 220 on the surface streets which I found weird. Any ideas? Tranny issue: I recently dropped valve body nice and carefully so I could replace the shift linkage seal which had a leak. I don't know what I did wrong but after reinstalling the trans will not shift from 2nd to 3rd. I also changed the vacuum line for the trans to be off of the manifold (originally was connected to the carb.
how about some pictures of the radiator, fan, shroud, etc? usually when you have a problem with cooling at highway speeds, it's because airflow is restricted, or the radiator is just too small. Sometimes there's a problem with the engine itself.
Maybe remove the shroud, but leave the fan? so the shroud does not restrict airflow at highway speeds, but the fan still moves air at lower speeds. also, what is the ignition timing under cruise conditions? it looks like you have vacuum advance, is it working?
On the transmission, which port was the trans originally connected to? Spark, Ported, or Main vacuum? What kind of vacuum does the engine pull at cruise? Did you reconnect it to the original vacuum source and see if it returned to normal function? Did you verify that the vacuum signal(inHg) was the same between the old and new ports? Enough ATF in the pan? On Overheating. Is all the cowling and hood attached when this overheating occurs? If the radiator is just exposed and no hood/side cowls the air may not be properly traveling through the radiator. It needs some kind of ducting and a pressure differential across the fins. You want the cool air to naturally pull through the fins and pull heat. If the ducting is poor, or worse it's causing reversion of hot engine bay air to be sucked out the front, the radiator will not properly transfer heat out of the coolant and can cause the radiator to heat up even more. This can become worse at higher speeds as the air just goes around the radiator rather than through it. With an electric fan this problem may be compounded if the temp sensor is located in a position that may see cool air. Sensor may be kept at a cooler temp than actual coolant temp and it never kicks the fan on. But at a lower speed the sensor is not over cooled by air and operates normally. Does the fan work normally? Or is it constantly on, or turning on/off even when it doesn't seem to be that hot? Is the Fan correctly sized for the application? If so is it correctly ducted for the radiator? The fan should not be a restriction in the airflow for the radiator. Are your positive your heads/block did not have any cracks before reassembly? Are you positive both head gaskets were installed correctly, Windsors have a 'front' to the gaskets, if one was accidentally flipped you may be encountering weird cooling issues. Test the coolant for combustion chamber gasses and over pressurization of the cooling system. This would confirm an engine issue and not an air cooling issue. With the engine held at cruise RPM(in park) look at the radiator hoses, make sure they are not collapsing. Condition of the water pump? If the impeller is faulty, or somehow grossly underdriven, there will be a lack of heat transfer due to the lack of coolant movement.
The overheating sounds like a too-small radiator. What happens is at low speeds the motor produces X amount of heat, which the radiator can handle. Get out on the highway and the amount of power needed goes up due to wind resistance, and so does the produced heat. This exceeds the radiator capacity by a marginal amount, so the temp slowly goes up. I've ran into this on a car I once owned, the car would slowly overheat while highway driving. I discovered it with a gizmo (the only one I've ever seen) that you temporarily plumb in series with the upper radiator hose and actually measured coolant flow and temperature through the radiator while running with the car stationary. The reading you got was then applied to a chart with engine and radiator size, as well as radiator material/design. The chart would then tell you the minimum size radiator needed. In my case, the radiator read 'small' (smaller than actual size), which indicated the radiator was partially clogged. That proved to be true; I had the radiator boiled/cleaned out and my overheating problem went away. That sounds like your problem too; either a too-small radiator, or it's partially clogged. It could also be restricted airflow at higher speeds, my car was stock so that wasn't the issue. The fact that you had this problem prior to the engine rebuild makes it very likely it's a radiator issue.
what do you have on the trans where the kick down should be, will the shaft move. your overheating I would bet has more to do with air flowing around the rad at speed or not having room to get out of the engine compartment.
I had the same problem with my o/t. I ditched the shroud & haven't had a problem since. Unless you have 2 electric fans the shroud reduces air flow at highway speed. I have seen people cut holes & install rubber baffles in their shroud to attempt to fix this.
We had a 302 do that after a valve job and cam change, we had the wrong head gaskets, our heads were from an H.O. motor, there was a conflict in the water passage holes.
Do you have the correct rotation water pump? Later ones for serpentine belt run the wrong direction for V belt....
At about the nine second mark of the second video, I seen a ripple affect. Perhaps you crossed into a time zone. Some times when traveling at warp speed a vessel will cause ripples in the surrounding atmosphere causing a severe pressure build up if the conditions are right. If this did happen as you were soaring at such a speed in your truck, you you have been sucked into a black hole causing less atmospheric air flow around your radiator and causing your motor to over heat. I think that the metalic sound at the end of the video was the radiation shield falling off.... Just a theory.... Sent from my SM-G930T using The H.A.M.B. mobile app
When you replaced the valve body, you may have overnighted the bolts holding it on. Very easy to do. Not sure what the torque is, but it’s not very much. Used to see bolts sometimes laying in the pan, when we used change oil by taking the pan off. The trans would be running fine. Bones
I suspect overtighten valve body also . Fords have band adjustments that will effect shifting . If it was fine before your repair , you missed something . Getting the shifter arm correctly attached to the valve body can be a PITA , sometimes and this will effect shifting because valve body things you are only wanting to shift into second and not high . About over heating , you are not by chance using late model water pump are you ? They are reverse rotation and you might be driviving your pump in reverse rotation of normal flow . SBFs don’t generally run hot . If you look at the front of the head where it attaches to the block you will see a “ square tab “ sticking out that is an indication the head gasket is correctly installed on a SBF .
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