I have a 1986 30' motor home with a ford CID 64k miles
I'm having some new cooling problem.
when i travel at 55 to 70 mph the engine temperature run above 220 + degrees
when I'm traveling 35 to 45 mph the engine temp is around 190 degrees steady.
is this a sign of a bad water pump? the water pump has new been replace.
The outside temp 69.4 f, 165 degree thermostat I was drive on flat roads in Denver, co.

 

possibly. also could need a good flushing with descaling chemical

 

When did you last replace the thermostat?

 

2 year ago

 

unless campers are extra special, the thermostat should be a 195 in the first place. low coolant temp=low sparkplug temp=fouled plugs,a nd air fuel mix not vaporizing completely, all adds up to low power and crappy fuel mileage. oh and harder starts with longer cranking. lots of bugs in the radiators. you prob have at least 3 coolers, engine coolant, tranny cooler, A/C condenser,and maybe oil cooler. the front 1 will be the worst,but you maybe have to unfasten them and layer them aside to get at whats behind. how accurate is you gauge just factory junk or?? gauges can also lose ground over time and become inaccurate. always good to check it against a heat gun for confirmation.

 

I have installed a after market temp gauge
I was planning on cleaning the fronts of all three radiators

 

I'm assuming ethylene glycol coolant, the old (GOOD) green stuff.
Have you been religious about changing coolant every two or three years? If not, time for a new radiator, water pump, heater core, and a thorough flushing. The silicates will precipitate out once they have done their job, and then corrosion forms and adds to the mess. Eventually enough of the radiator is filled up with gunk that cooling is inadequate. And the block fills up as well, preventing coolant from getting to where it needs to be. Hence the need for a seriously thorough flushing. If it has been neglected for more than 5 years, it may be terminal.

Or have you added anything but the green coolant without flushing? Some combinations of coolant chemistries can react with each other and form gels and other nasties.

If you have taken good care of coolant for its entire life, then check the temperature of the radiator itself when gauge reads high. Those cheap pocket sized IR thermometers are perfect. And check in multiple locations on the radiator. I'm assuming the gauge is in the engine block?
If the upper half of radiator is hot but lower half is more than a few degrees cooler, the radiator is filled up with crud.
If block is hot but entire surface of radiator is just really warm, then suspect inadequate flow (thermostat or water pump).
If block and the entire surface of radiator are both really hot, then you've got a more serious problem.

 

first take off the bottom hose and using your garden hose and a rag to plug up the slack,back flush the radiator.while you have the lower hose off,make sure it has a spring in it to keep it from closing up at higher rpm's.also make sure no belt is slipping.she,s getting old you know.