1999 expedition overheating

A true overheat is when the coolant is bubbling back into the coolant recovery tank. #1 radiator cap not holding pressure #2 stuck thermostat #3 restricted air flow #4 bad fan clutch #5 bad waterpump #6 restricted water flow in radiator #7 blown head gaskets this is the end results to a overheated engine .

so the RAD is going to be good with leaks that it?
it has to hold pressure or it will get too hot,
14psi pressure,
I take my IR heat gun and check all rad tubes
top and bottom
and find, 3 are not 50 degree,drop end to end read same
those 3 are clogged, now you have 2 reasons to replace that bad rad.
something smokes, what?
it dont overheat parked, what is outdoor temp, 75f like here or 0F?
it must overheat idling, if it does moving.
how fan it not?
wont overheat A/C OFF you said.
so its marginal

ether rad tubes clogged
or fans dead,
one or both.

REPLACE RADIATOR PRESSURE CAP AND CHECK THE COOLING FAN CLUTCH.WHEN YOUR ENGINE HOT WHEN YOU TRY TURNING CLUTCH FAN WITH YOUR HAND WHEN ENGINE IS HOT.THERE SHOULD BE RESISTANCE IN THE FAN.IF CLUTCH FAN SPINS FREELY WHILE ENGINE HOT.YOU NEED TO REMOVE COOLING FAN TO REPLACE CLUTCH.

check fan, and also have the system it pressure checked for any internal or external leaks.










TIM.....

Do you have electric fans and if so are they coming on, fans should come on when you put a c on

Here are a few things to try. Check your Radiator cap pressure as a weak cap will boil over more quickly. Replace your Temperature sending unit. There may be 2, one is for the dash gauge and the other is for engine control. Unless you have other signs of overheating you may not be overheating at all, just a bad sender.

Next, the cooling fan clutch is what the fan blade is mounted on. This is checked by using a Timing light with a RPM tach made into it. The fan clutch "locks" at a variable temperature. In cold weather it slips internally. In hot weather it engages or "locks". A mechanic measures the RPM of the blade to the RPM of the engine. This tells if the fan clutch is slipping too much internally.

Before considering a new water pump try a free scan at Autozone or Oreillys. If your Catalytic converters are plugged the engine will overheat. You should have a Code for this problem in the onboard computer. About all you can try after this is to remove the Thermostat completely and see if the engine still overheats.

You will have to replace the New Thermostat again because the other engine controls will not work right without it. But without the thermostat you can test for collapsed Radiator hoses at say 2500RPM or above. Thats about all I can think of, the water pump would cost the most. The cap, sensor-sender, fan clutch, and hoses are not that expensive.

check ur oil if color of grayish chocolate milk and or white smoke from tailpipe pretty sure signs of blown head gasket

more probable is fan clutch

The most likely cause of this is the fan not kicking on... and the best place to start looking is the fuse for the rad fan (under the dash). If this is good check radiator thermo-switch... Observe the engine as it comes up to operating temp... if the fan does not kick on by about 200 degrees, disconnect the terminals at the switch and connect them together briefly. If the fan comes on then the switch is faulty, if not then suspect the cooling fan relay. If the fan runs normally but vehicle still overheats, the next thing to check is the T-stat. Feel the upper hose when at operating temp... it should be warm... if not remove the T-stat and reassemble... if the problem goes away it was your T-stat, if not it is either a bad pump, or a restricted (clogged) radiator. If the pump is not noisy or weeping coolant, it's probably OK... Hope this helps...;-)

I had the same overheating problem in my jeep ! My problem was finaly found out to be the clutch in my fan its a different kind of clutch system it work as this. When your jeep gets warmer the tighter your fan clutch gets .While cool your fan moves slowly. now to test your clutch just warm up your jeep and rev it up a bit if your fan dose not pick up speed then it is sliping.What will come out of this is that you fan will the seez and run full all the time. if you jeep dose not overheat wile moving then it is not your thermo stat period.