The good old radiator

I have an older MH with the 454 and fought this overheating problem for several years. Headers made a huge difference in dissipating heat. Once it was a thermostat that did not open all the way. I bought 3 and even one of the new ones did not open all the way. After testing in boiling water the one that opened the widest I drilled several #40 holes in the flange for more flow and that made a huge difference. They sell hi flow thermostats with the pilot hole already there for HD truck applications. Also Dave helped me with the IR gun for checking the radiator. Many people assumed that if an old MH is overheating it is the radiator. The way I checked it was to shoot the inlet at the top and mark the reading, then every 3 ins take another reading from left to right in a grid pattern until I got to the outlet at the bottom. I had to hold the clutch fan with a rag and rotate it to take readings in the middle. From what I have learned is that when they start to clog they clog in the middle first. There was a delta T of 50 degrees F from top to bottom with no cold spots (which would indicate a blockage). During this test I found I found that the temp sensor in the L/H head was 20 degrees higher than the thermostat housing, which gave a higher reading. I think if you have a delta T of 30 degrees or less and cold spots you probably need a new radiator. If not some air dams to force the air through the radiator might help as well as a high flow thermostat. One thing I learned in this quest for lower eng temps is going to a 180 degree Hi flow thermostat helped reduce temps in the heat of the summer but would throw eng codes in the fall and winter. Hope this helps.