Hi Folks,
I've read all of the posts I can find on overheating and radiators on 300TEs and E series. Hope you can help, as I think we've covered all of the bases.

I bought this car one year ago with 144k miles on it. Second owner had had it for 8 years and the valve job was done at 112k. Received maint book with the car.

At 146.8k/Dec. 01, noticed coolant loss. Mech diagnosed weak fan clutch, overpressurized system, and leaking water pump. Repld fan clutch, water pump, and serpentine belt and gates.

At 149.6/March 02, noticed another coolant leak. Mech diagnosed colant leak at heater core, advised dealer repair, due to complexity involved with pulling dash. He BYPASSED the heater core and put a new heater hose on.

At 151.3/May 02 replaced expansion valve on AC


MOVED FROM TX TO FL

at 155.3/ July 02 replaced battery, alternator, and belt tensioner assembly and damper.

At 155.6/Aug 02 rebuilt transmission and complete tune up.

At 156.3/Sept. 02, was driving car when engine overheated. Pulled off road, let engine cool, added coolant and attempted to drive home. Note that it took apprx 2 hours for engine to cool down. This wasn't fun with groceries in car along with 5 year old and 2-1/2 month old!!! Drove 1/2 mile and temp started up into red zone, so parked the car and waited for hubby.

Had it towed to my mech's shop and did the following:

replaced the radiator with a new Behr unit
replaced high speed aux fan switch
replaced coolant level sensor
replaced fan clutch (again!)
replaced upper and lower radiator hoses

They worked on the car for several days, as the new radiator didn't completely solve the problem. The did a head gasket leakage test (fluid color change in test kit indicates leak) and it was inconclusive, so we didn't change the head gasket. Would it be bad 44k miles after valve job? How much does it run to replace? I picked it up a couple of days ago, but waited until today to really drive it.

Started it up, went through drive through at bank (5 minutes) and then hopped on the interstate. All normal, temp was just below 100, like it was before the overheating incident.

After driving approx 17 miles, 20-25 minutes, temp started creeping up to approx 110. I made sure to cycle compressor on and off and that, of course, would make the temp drop to between 100 and 105. I was running at 65 to 70mph, when i slowed down some, the temp seemed to drop. Went to the store and shopped for apprx 1 hour. Came out, started car and temp was normal. Drove home and same thing happened, although sooner, since car was already warm.

Aux fans engage properly, temp never went above 110. Temp seems to go up when car is moving, rather than when idling at stop light---it almost seems like the airflow coming through the grille and radiator is blocked in some way, as there doesn't appear to be any cooling coming from the air moving across the engine while driving. However, I find that hard to believe since mech worked off and on for over a week.

Here's the million dollar question......does the fact that the heater core is bypassed have anything to do with this problem? As I'm in South Florida, my mech advised to not repl the heater core until the evaporator goes, as we really don't use the heater but a couple of times a year.

I love the car, but after having put over $5k into it in a year, I need to make a decision about keeping/selling. I"m willing to try the heater core replacement, if one of you experts thinks that could be the problem.

Thanks for helping in advance!!

Donna