4.0 overheating on highway

[fordzilla]

hey guys i got a over heating problem on the highway with my 4.0 it stays cool just for crusing around town but ones ur doing about 90 100 the temp starts going up ive put new thermostate, new clutch fan, fan, theres no leaks and the rad iset damaged or clogs so im not sure wut could be the problems if u have any ideas let me know and it would be greaty appreciated thanks.

 

[Ozwynn]

air trapped in the system. Jack up the front of the truck a couple inches (or park on a hill) and take the radiator cap off and run the engine, add coolant as the level goes down. Replace the radiator cap with a new one.

 

[fordzilla]

thats all u think that it is?

 

[MAKG]

Dude, "you" is spelled Y O U. Don't make me interpret your writing if you want my help. Use the spell checker.

Air bubbles can cause overheating, but a really easy diagnostic for them is that the engine makes irregular knocking sounds after it has been shut off, as the coolant boils. Highway speed overheating can be caused by quite a lot of things, but the most obvious is a plugged radiator.

 

[fordzilla]

sorry about that man my bad but my rad does not seem to be pluged so ill try doing what you said see how it works.

 

[woodyedmiston]

Overheating

Did you put the thermostat in correctly? Do you still have the original equipment air dam box in place under the radiator.

Don't poo-poo the man who is telling you to fill the engine running - you can't get enough water and remove all the air with the thermostat closed.

 

[fordzilla]

i will try it out and get back to tell how it works/

 

[Robin Hood]

It could also be (but very doubtful) bugs clogging up the front of the rad....

But city temps would also be quite high.

 

[Exploder]

Just some food for thought,

I think all of the suggestions are good.

Since you just replaced everything, The 1st thing I'd check is to make sure the thermostat is either working or facing the correct diretion.
To check if it is working put it in a pan of water on the stove. boil the water. As it get's hot it will open. If you need to know what temp it is opening use a candy thermometer. (or a digital guage if you have one)

If you don't want to pull it appart to check it. Start w/ as cold motor. Pull the cap off the radiator, fire it up and run it until every thing warms up. You should see water circulating through the radiator. It will push some water out as things warm up so keep your pets away (antifreeze) (If your neighbor is a tree hugger make sure you do this on thier front lawn )

By doing this you are checking that your water pump is working and the thermostat is also working.

If it's over heating on the freeway and not around town, you may also want to check out the thermostatic clutch on you fan. If it does not lock up you will not pull enough air though your radiator, just because it's new doesent guarantee it is working right

Also, your heater core is part of your cooling system (easy place to trap air). so while checking for air in the cooling system, dont forget to turn the controll to heat while you are running the motor / filling / burping the system.