I had the water pump go out on my truck so I replaced it and the thermostat. After replacing it I can't get it to warm up past the cold line on the gauge. I tried replacing the thermostatic clutch and the thermostat (both parts are motocraft) for a second time with no luck. I've also completely blocked the front grill. The upper hose gets warmish and the lower hose stays between 30-60° F (temp gun), Upper hose makes it to 110 at most. I've also made sure the air has been completely burped out of the system. I do live in Minnesota so I warm the truck up for about 10min before driving and after 30 min of driving the best I got was 110. Any ideas on what to replace next?

99' xlt 3.0 flex fuel 87,000 miles

 

make sure that you orient the thermostat correctly , it may jammed open by the internal casting

i made that mistake once , the thermostat is shaped a certain way to properly fit into the hole

 

I checked the thermostat and it's in the correct way. I just noticed that I don't have the skid plate on the front of the truck either, could that be part of the problem?

 

that is not the problem , the thermostat is the suspect

have you done the hot water test , the thermostat is opening too early , the coolant is being constantly cooled by the radiator

 

If by hot water test you mean putting it in a pot of water and bring it up to temp I have not, I'll give that a shot. What concerns me is that the lower radiator hose stays cold while the upper hose gets to about 110-125. Which leads me to believe that the thermostat is staying closed.

 

you have the info back wards 110-125 degrees which indicates the thermostat is staying open or being jammed open when warm

or just a faulty thermostat , which is actually good ,
you never want a thermostat jammed in the closed position ( engine overheat )
meaning

you should replace the coolant temperature sensor , if you are using green coolant ( requires a good flush ) the sodium in the green coolant wreaks havoc on sensors

it may be giving a false reading

replace the coolant with the yellow coolant

 

Its had a complete coolant flush when I did my water pump. The 110-125 temp I am referring too was done with a temp gun aimed right at where the sensors read and done directly on the coolant. The gauge on the truck roughly reflects the reading. Would a bad sending unit cause this issue?

 

plastic and rubber are not good places to read coolant temperature

you should have pointed the temp gun at the radiator fins

the fins and tubes will give a close to accurate temperature reading

i always replace coolant temperature senders when i replace thermostats

it is always cheap insurance to do the water pump / thermostat / sender all in one shot

 

Ok I'll retest it there after I replace sending unit tomorrow.