my 98 expedition keeps over heating, i replaced the water pump, thermostat,coolant. it will be fine one minute then it overheats. weather im on the road or sitting at a light. i also replaced the fan clutch. thanks!
If you have the 5.4L motor it will have a plastic intake manifold. Look at the front. There is an aluminum crossover pipe attached to the front on the top. Those are famous for leaking aroung where the intake meets the head and where the aluminum and plastic meet. You may need a flashlight and a small inspection mirror to check all the way around. Also if the valley or apace between the heads has coolant sitting in it that's a good bet you have a leaking crossover or a head temp sensor leaking. The head temp sensors are located at the back of the heads. The other common spot for coolant to leak is the heater hoses be sure to check at all the fittings and make sure they haven't come apart up by the firewall. One last thing to check is the belt around the water pump pulley. It is easy to put it on so the water pump spins the wrong way. Common mistake. Lastly if the manifold IS leaking do NOT attempt to do this if you do not have a top notch torque wrench!!! You can very easily strip the bolts or holes that are in the heads. If you are not sure take it to a good technician. Dorman makes a good replacement manifold for about 200-300 bucks. The gaskets are made onto it. I have had no issues with that one leaking. Also do not try to relpace just the crossover... I know that it has bolts and they sell gaskets but it will leak. If the manifold needs to come off it is also a great time to change the plugs. They will be super easy at that point, be sure to use new Injector o-rings too. Hope that helps. Jim
Check the compression,could be a broken ring.
I would check the radiator first and if its not it then your looking at a bad head or head gasket if u have already replaced what u said u have
