Okay I'm lost, 2004 Ford Freestar, 3.9, 107000 miles. Overheats when driven over 60mph, Thermostat has been changed twice, Radiator is new, lower radiator hose is new, electic fan relays have been checked and appear to be working, Fans both work, heads have been removed and there were no blown gaskets or noticible cracks, Exhaust gas test is negative, leak down test is negative, when overheating the radiator overflows so we know it is not the gage. Removing the thermost seens to help some. A can of block sealer did not help, The only possible related item is that I get AC but no heat. This seems to be a problem with the dash heat control valve, two mechanics have given up. I, m also a mechanic and I am out of ideas. Can you see something I have missed? Thanks
You may have a block issue from the overheating. You said the heads were pressure checked for cracks? If not, get it done.
Otherwise, it sounds like you covered all the bases.
July, 10, 2012 AT 11:20 PM
Since there was no one locally to test the heads the shop reinstalled them. The thermostat is back in. The confusing issue is that I can drive this car for at least two hours below sixty and the gage stays normal. I blast up to 70 and the engine haets up. As soon as I pull over the temp drops to normal within 30 sec.
July, 11, 2012 AT 12:18 AM
It sounds like a circulation issue either with the water pump or the radiator. Was there much gunk in the system?
July, 15, 2012 AT 9:13 PM
Radiator was replaced. I think I have it narrowed down to the lower rad hose. Even though it was only 6-7" of free space I think the hose was sucking closed at higher RPM. When I slowed down the hose would open back up. The radiator shop it appears did not change the hoses. Rep; aced the coolant put in a new hose, lowered the thermostat to 180 deg. And after 45 miles in 85 deg heat the temp is staying normal. Thanks for the help. Sometimes you just think you are going nuts going nuts when the regular things do no not work
July, 16, 2012 AT 12:03 AM
Did you change the rad cap?
July, 20, 2012 AT 2:26 PM
Sorry I was out of town for a week. Do you think that will help. It has a plastic pressurize overfloe tank
July, 20, 2012 AT 11:29 PM
Change the rad cap as it may be bad or full of crap.