Okay here we go. 97 F250 HD with 460 and e4od.160,000 miles, MSD 8.5 Super Conductors, Mallory 6A, KNN air filter, Transmission Flushed new filter including inline and Mercon V. New Hedman Headers and Y-pipe into Cat delete stock exhaust. New front fuel pump and filter. New 38 gallon conversion rear tank and fuel pump. Air pump delete. New IAC valve. Timing set to stock. oil just changed Valvoline high mileage full synthetic, KNN oil filter , Lucas Full Synthetic oil Stabilizer, Injectors cleaned on truck with Berrymans, Entire cooling system has been thoroughly flushed. New 4 core radiator and 180 degree high-flow thermostat, new belts, new water pump, new hoses, new 13lb rad cap.
So here's the problem. It gets hot under acceleration. If I do a 0 - 80 mile per hour run the temperature gauge will go from a steady "O" reading to the high side of "R" (of course I am referring to the word displayed "NORMAL").. if I am Towing 0 - 65 mile per hour run will put the Gage to a solid "A" Reading then drop quickly once the throttle is lifted. It can idle all day long with the AC on and it will not come above the"O". I would normally think that this has caused buy a stuck thermostat however the thermostat is new and a stuck thermostat while running easy, would most likely cause the lowest temperature to be around the letter "N" on the gauge. I have no condensation coming out of the exhaust whatsoever except what is normally associated with first start up on a full exhaust system. I have no additional pressure or bubbling in the radiator. I have no foreign fluid in the radiator either from oil or transmission fluid being introduced. And I have no coolant contaminants in the oil at all which would normally indicate a head gasket or intake issues. This is definitely a concern because Towing an RV in hilly conditions will allow the gauge to climb rapidly. The bigger the hill the longer and harder the acceleration the higher the temperature will climb. I am stumped.

 

With the new radiator did you put the fan shroud back on? Is it like it should have been from the factory?

Have you verified clutch fan operation?

 

Yes fan clutch works fine. Obviously anything over 35 miles per hour the fan clutch doesn't really cool the radiator at that point anyways. Also the fan shroud is positioned within three eighths of an inch of where it's at originally allowing the blades of the fan to still be basically half in and half out of the shroud. I should have also mentioned that this problem existed with the original Factory 2 core radiator also. All the changes that I made to the cooling system was to address the problem that I posted.

 

perhaps then, a water pump issue or maybe you can add an electric fan.

 

Brand new, not rebuilt water pump. Unfortunately I could add 5 more fans but the fan doesn't really do anything over 40 mph and definitely doesn't add cooling air at 70 mph.. With The old water pump on it did the same thing..

 

Are you sure the temp sensor is giving an accurate reading?

 

First, never assume a new part is a good part. It may be bad, it's just new. I've had bad thermostats, right out of the box.

Second, and more important, The N-O-R-M-A and L temp ranges are all OK. They are normal. It's OK.

I've noticed with past trucks that I own that when the radiator is filled up with water, you tend to see more movement on the temperature gauge.

 

As engine load increases The rate in which the engine generates heat makes the gauge climb consistently faster than normal.. The heat that is coming out of the heater core and underhood Temps are increased in direct relation to what the gauge is reading when compared with digital/infared temp gun.

 

the previous water pump and themostat did the same thing, all the new parts were added to address this issue.
All the Ford vehicles I have owned starting in 1984,(18 to be exact) that had the "normal" temp gauge, if it was running on the "m" or "a" consistently at best you have a minor cooling issue at hand(stuck thermostat, low coolant, collapsing hose, etc.. If you are on the "l" you need to pull over because another 5 minutes of driving you are going to blow a head gasket if you hadn't already.. I am very unclear how more coolant would cause greater fluctuations on the gauge as it would be a larger body of liquid therefore making it harder for the liquid to change temperature (like heating a swimming pool vs a bathtub).. Usually low coolant levels make the gauge jump to extreme highs and lows due to not enough coolant to keep the sending unit covered consistently..

 

Is the truck over fueling? Have you replaced the oxygen sensors.I know you said you checked your timing , but has your harmonic balencer spun on the rubber and moved you timing marks? I don't think your cooling system is the problem. I cant remember if that year has a knock sensor. Is the sensor failing and messing up the timing?

 

Can you check what the water temp is with a scan tool? The one wire senders are not very accurate but the ECU will be seeing the correct temp.

If you can't check a data stream, try putting a water temp gauge in and see what temps you are actually looking at.

 

I think Chris on to the best thing. Add an actual water temp gauge and see what the real reading is.

 

The balancer looks tight. I use to play around with 302 vacuum advance cars timing in the past to see what I could get away with and other than there is no knocking/pinging noise they climb in temperature is similiar to those old cars when a I went too far advanced.. I might have some poor injector characteristics(spray pattern/drip) but with the improved ignition/wires.. I don't think I would see that much or a wash issue, especially at full throttle and I have not seen any excessive soot in the exhaust even without the cat on.

 

I'll have to gage it..to see what is actually happening..

 

Yea, I'll have to put a gauge on it.. I'll respond with what I find out..Kind of rainy and cooler today, not dealing with that...