Mechanics

F350 7.3 L OVER HEATS

2000 Ford F-350

2000 Ford F350 V8 Four Wheel Drive Automatic 122000 miles

The truck will run all day at 55-60 mph anything over 60 and the temp runs right up to the red.
I have back flushed the rad, change thermostat, changed the coolent, I lose no coolent nor do I have any bubbles in the coolent as the engine runs. Every now and then I can't get any heat from the heater. I put a new water pump on and the fan free spins when engine is off. The serptine belt is on the right way. I keep getting a bad head gaskett " guess" from guys that what to help. But I just can't believe thats the trouble.
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ROADSIDERON
March 11, 2008.



On a 7.3 you would have other issues if it were a bad head gasket. Are you having other issues with the way it runs above 60? Does it run rough, lack power? It may be a turbo issue. Let me know how it runs and I can get you some more answers.

Tiny
Flexy5
Mar 11, 2008.
Truck starts good, no excess smoke, runs good. I havn't pulled a trailer yet to see if it over heats under a load but I do think its going to. I have run it hard in 4 wheel drive in deep snow and the temp shot right up to the red. The heater part of the problem has got me thinking of an air bubble stopping water flow.
I pressure checked the system and found no pressure drop. The problem with the heat seems to get worse the colder the outside air temp is.

Tiny
ROADSIDERON
Mar 12, 2008.
When the engine registers hot, check the engine block with a temperature probe or infrared thermometer. I wonder if the temp sensor is bad. Maybe it's not actually overheating, but the sensor is bad. Check it manually and post back your finding.

Tiny
Flexy5
Mar 12, 2008.
Ok, I did the temp check to day. When the temp go's up so does the reading on the inferred gun. But it cools down very fast. Just about the time it takes to pull the truck over and get the hood open its back down to operating temp. When the heater blows hot the air from the dash vent its 115 deg's. When its worm air its around 70. Now this AM I drove it 25 miles didn't get any heat until I drove appx. 15 miles engine water temp about 94 deg. Shut down for about 45 min. On the return trip had worm heat right away. When I had temp gauge in the red zone I didn't get any real hot air from the dash. Haven't lost any coolant. When I drained the system I got 6 gals. That's just what I was able to put back in it when I refilled the rad.

Tiny
ROADSIDERON
Mar 14, 2008.
115 from the vents isn't that bad. I've seen vent temps reach as high as 130 on vehicles without overtemp issues. On your original post you mentioned the fan turns free. How free? There should be resistance from the fan clutch. If there isn't enough resistance, the fan may not be doing it's job. Also check the front of the a/c condensor and see if there is debri blocking air from moving across the radiator. We know it's not a head gasket, or a drivablilty issue. Now we just need to dig a little deeper.

Tiny
Flexy5
Mar 14, 2008.
Rad's clean. When I put the new water pump on I cleaned both rad and a/c condencer. Today it was 50 and the frist run I had no heat, Ran it up to 75 mph and engine temp went right up. Still no heat. Shut it down for about 1/2 hr. On the second trip had heat, worm but it was heat. Ran it up to 70 mph engine temp went up heater temp went down?
I think I'll hang a for sale sign in the window!

Tiny
ROADSIDERON
Mar 16, 2008.
I want to apologize. I may have been misunderstanding all along what your concern is. Are you saying the engine itself is overheating, or the cabin air fails to warm up. Big difference, and I think I may have been on the engine problem. If you aren't getting warm air in the cab, it is probably due to a faulty blend door actuator. It regulates air flow across the heater core and may be sticking. Let me know which one it is. I apologize if I'm on the wrong track.

Tiny
Flexy5
Mar 20, 2008.