Originally Posted by BA-in-Mich
Mine currently comes on even at 180*. I did power wash the front a/c coil this summer. That helped mine from coming on at 181*. Mine for the last couple of years has been coming on at 181* and going off at 179*. Once the outside temps hit 80* my fan stays on but I'm always at 180* give or take a degree or 2. What I think is happening is a dead spot has occurred in the middle causing more heat to hit the clutch thus turning on the fan. I have (2) 12" fans in front of all this with override switches but that has never helped. Of course I have an oil cooler and a external transmission cooler in front of all of this so there is quite a bit of heat being pulled through the radiator. Next season I am going to try building air dams to direct more air to the center of the radiator to see if my theory may be right.
A couple of points, and I am not picking on you.
1) You should not power wash a radiator. The pressure of the water will bend the fines.
2) When flushing a radiator you should wash from the rear to the front.
3) I do not know if you have a cross flow radiator (GM 454, would lead me to believe that you do) but if you do and have a dead spot in the center, even a couple of rows would mean you have lost a substantial amount of cooling from the radiator.
4) A dead spot is a sign of things to come, now is the time to replace the radiator.
5) If you have a dead spot you can check easily, once the vehicle is hot place you hand carefully on the fines or use a heat gun. A dead spot can be found by looking for a row of fines that are much cooler than the rest of the radiator.
6) Your signature says you have recurved your distributor. I assume you advanced the timing to produce more power. Advancing your ignition timing increases cylinder temperatures and heat to the cooling system.
7) You are really looking for torque in a Motor Home engine, not HP, Hp equals upper end speed, torque equals twisting power, or power to get the motor home moving from a stop.
8) One thing you could do is reduce the thickness of the stack of heat exchanges you have at the front of your vehicle. You can purchase or make yourself stand alone oil and transmission coolers. This will greatly increase the amount of cooling the radiator can do by reducing the amount of heat passing through the fines. These stand alone coolers have their own thermostat set to the ideal temperature for the oils passing through them. You could use your existing coolers by removing them from the stack and mounting them separately under your motor home and adding a temperature sensor and electric fan.
Note the fan says oil cooler on it. The ideal temperature of your transmission and engine oil is different from the temperature you want your coolant at.
If you need any help with any of these thoughts I would be happy to help you out.