Need Desperate Help with Overheating and Boilover

[Firedawgy]

I really need some help, for some reason I cannot post in 911 area. I have a 2002 XLT 4.0 4wd. Driving down the road and red warning light comes on, engine temps in the red and you could smell it starting to overheat. I made it to work and saw that the coolant tank was empty. I filled it and drive home later. Same thing happened later that day. I was noticing that it was wet all around the tank, leaking around the cap. Replaced cap, no luck, noticed that the top radiator hose was rock hard. Changed thermostat, no luck, still leaking, hose still hard. Took to mechanic who said he would let it run for hours and not overheat, then shut down and restart and it would overheat, at least on the guage, though he did say he saw the temp guage spike even when the engine was cold and running sometimes. He changed the waterpump, no luck, and tested head gasket, no leak there. We are baffled, its now an intermitent problem and I don't know what to do. Saw a sensor on top of thermostat housing, maybe thats it? I know the dealer will ream me if I take it in. This is my 7th explorer and by far the worst, what was ford thinking when they built this model . I want to fix this, sell, and then ponder if I want to risk a sport trac. Oh please someone have some good ideas for us to try.

 

[Exproblems]

I really need some help, for some reason I cannot post in 911 area. I have a 2002 XLT 4.0 4wd. Driving down the road and red warning light comes on, engine temps in the red and you could smell it starting to overheat. I made it to work and saw that the coolant tank was empty. I filled it and drive home later. Same thing happened later that day. I was noticing that it was wet all around the tank, leaking around the cap. Replaced cap, no luck, noticed that the top radiator hose was rock hard.>>>>>>>>>>>>>>>>>>>>

How much coolant did it take to re-fill the system after you made it to work and you topped off the system? When you saw the coolant leaking from around the cap on the expansion tank later in the day after you refilled the system, was the tank completely full of coolant as if the coolant in the system was backing up into the expansion tank? If so, I would think you may have a plugged up radiator. Did the mechanic check for that?

>>>>>>>>>>>>> hose still hard.>>>>>>>>>>>>>>>>>>

Like I said above, radiator must be plugged up because the upper rad hose is rock hard from the coolant not being able to flow into the top of the radiator and circulate thru the system properly. The blockage is causing the coolant to back up in the system and exit thru the expansion tank cap. This is my hunch, I'm no expert on cooling systems.

>>>>>>>>>>>>>>>>>>>>Took to mechanic who said he would let it run for hours and not overheat, then shut down and restart and it would overheat, at least on the guage, though he did say he saw the temp guage spike even when the engine was cold and running sometimes. He changed the waterpump, no luck, and tested head gasket, no leak there.>>>>>>>>>>>>>>>>

The mechanic had to let the vehicle run for "hours"? Sounds a little fishy to me that it took hours to let it run and do a check on it. He changed the water pump on a hunch? Expensive hunch. Water pumps tend to leak thru the weep hole when they go bad or the bearing shaft for the clutch fan gets a wobble in it. Take it to another mechanic and have the radiator tested for blockages. You already changed the t-stat and water pump, tested head gasket, so not much else left to check. Don't know if a blocked heater core could cause something like this, but the radiator seems more likely to me.

>>>>>>>>>>>>Saw a sensor on top of thermostat housing, maybe thats it?>>>>>>>>>>>

Even if the temp sensor is bad, I can't see it causing a blockage in the system causing an over flow from the expansion tank. It should just give you a false temp gauge reading. The sensor doesn't control or alter the flow of coolant thru the system.

>>>>>>>>>>> I know the dealer will ream me if I take it in.>>>>>>>>>>

Why would he do that, he made money off of you right? I would be reaming him out for not fixing the problem the first time around and replacing parts that weren't the cause of your overheating costing you a bunch of money. Good luck with this!

 

[corkey]

if it over pressures it will send the coolant out the overflow tube too, cause the cap is designed to only hold so much pressure , than allow the excess to go to the expansion tank.

i would drain the system, pull the rad hoses and make sure they are not blocked in any way, or collapsed inside where you cannot see it,, as well

 

[Firedawgy]

when I first found the issue going to work when I pulled the cap the tank was empty, I let it cool for a few hours and then put quite a bit back in, like over a bottle to reach the cold full line. The next day I checked it again, after I drove home and it was cold, the overflow was down about 1/2. I talked to the mechanic today, he said that the car is not leaking any water anymore, after changing the thermostat from the one that I changed. He didn't remember checking the hose though to see if it was hard. He also said that it will still peg the guage, sometimes even when its cold so he's thinking the sensor is sending bad info to the guage. Maybe I should just take it to the dealer.

 

[Exproblems]

Maybe I should just take it to the dealer.

>>>>>>>>>>>>>>>>>>

Good idea. I would take it to a more qualified mechanic than the one you were using.