5.0 Cooling System Issue

[RandomNerd2000]

I've got a 2000 5.0, 257K on it, with a coolant issue that started small and has gotten to be an issue, the truck had what was seemingly an open thermostat, wasn't reaching operating temp, didn't bother me too much, then it started running at normal temps like it was just stuck from sitting, so I didn't worry, now it's trying to overheat, coolant is full, heat is cooking hot, did notice when it's most of the way cooled down, but not entirely, you can take the cap off without pressure release? Does the same thing warm, checked it CAREFULLY, not the smartest thing I'll admit. Got a new thermostat here to go in it now with some RTV setting it up into the housing, but I'm not 100% on that being my issue, input?

 

[CDW6212R]

If the coolant has been full, then the thermostat is the only thing which would affect temps that much. If it's an old T-stat or you don't know how old it is, then it's time to replace it, same for hoses too. It sounds like it's time for replacing those parts.

FYI, the most common death of a 302 in these Explorers is from over heating. That's usually going to be from a bad T-stat or neglect. You've caught it in time, fix it now and it'll be great again. The heater hoses are a little tough to find now, Ford obsoleted three of them I think. Try Rock Auto.

 

[RandomNerd2000]

Thermostat and radiator cap fixed it, radiator cap looked sorta tough gasket wise and the thermostat was factory OEM, also did the hoses while at it, should be good to go now.

 

[CDW6212R]

Well done. The cap usually fails by that seal piece inside, as you noticed.

I had a Ford cap quit after maybe 15k miles, but ten years old. I tried to use it on my newest truck when I did the system(knowing I bought it new for the Mercury), but it didn't let the overflow coolant pull in. So I put the old one back on until I bought another new one. Then the two new ones I got from Amazon, were the wrong size. They said they fit our later trucks, but they were bigger, which is what my older Lincoln uses(and the 1st gen Explorers, all 80's Fords etc).

 

[RandomNerd2000]

I think radiator caps mostly have a time limit on their life more so than miles, my 01 had the factory cap, worked right too, I got a new one for it when I got it though, both my 99 when I drove it and my 2000 had to have caps to replace the OEM ones, the 99 was leaking to the outside around the seal, the 2000 wasn't building pressure, mileage ranged from 152K on the 99 to 257K on my 2000.