Hello all, I have an 02 1500 sport 4.7 that I bought new. Over the years I’ve replaced 4 radiators, 2 water pumps a dozen top radiator hoses and thermostats. In the past 4 years, If I drive conservative, temperature stays normal, but stand on it, to clean it out or passing a long list of traffic, the temperature will go to cold!!! To the point in the winter it will peg the cold mark. It also sets off an engine code .
What do I replace next ?? Except for timing chain ( cloys ) complete set it’s never been apart.

 

That's a thermostat problem..... Get a stant super-stat.

 

Follow large bottom hose going from radiator to engine block. Where it attaches, is the housing where the thermostat lives. Don't strip the bolts and don't turn the new thermostat the wrong way around. Again, depending on where you live, those bolts can get pretty rusty and they're pretty long and skinny. Patience and plenty of penetrant will get them out. I dipped mine in grease when putting them back in. Big pan for the coolant deluge. It's the lowest point on the engine, aside from oil pan.

 

First I always use A Stant super 👍. And I turned it around yesterdy and the temp went 3/4 to hot and never came down. Let it cool off and tried it again, same over heating, reinstalled it with the temperature element in the engine block, it takes 15 minutes to heat up. After driving on the interstate, I run it up to clean out the carbon, at 80 degrees outside, temperature of engine went down to the 1/4 cold mark. Drove like grandma it came back to normal.
Next ideas ???

 

Thermostat is what stabilizes engine temp. If it still does the same thing with a new one, something else is going on. Might be time to test the coolant for combustion byproducts.....

 

I had that tested already, no gasses in the coolant no coolant losses or oil consumption 👍. You can put the heater controller to high, put air flow through the vents and feel really hot air. until you stand on it, temperature guage will show colder and the hot air will cool off to barely warm. So it’s not a electric problem
since new, it will eat the top radiator hose ! When it blows, I cut it open and the rubber will be gone and the cords will be showing!!! Just like a worn out tire !

 

Something ain't right there..... Radiator hose should last decades..... being eaten up from the inside suggests either the wrong coolant being used, or, some other variety of contaminant in the coolant.

Heat going away if you step hard on the gas suggests low coolant....... maybe an air pocket that isn't getting purged? That can lead to some really strange cooling system behavior...

 

As I stated before it’s ate upper hoses since it was 5 years old. The hoses look like high volicity water erosion ! I still use the o oem recommended coolant.

 

Have you flushed the cooling system? It really shouldn't do that. Makes me think there is sand, or scale in the cooling system, eating the hose. That's just bizarre.