2002 7.3 overheating
Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
Here's the thing about the fans. You are correct, you do not need them at highway speeds, but they should come on when an engine is overheating just as they do pulling a grade loaded and so forth. In this case we have two fans, one new and neither fan comes on. That suggests the engine is not actually overheating and causes one to focus on the gage was erroneous.
My two cents,
Steve
My two cents,
Steve
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Cross-Country
Joined: Aug 2003
Posts: 91
Likes: 0
In my ongoing testing, I replaced the sensor. Took it down the highway at 75 mph for 10 miles and no overheating...but suddenly it started again. This time, I had a leak from the thermostat gasket from r and r ing it too many times. Blew about 2 gals out and thst did it! Fixed the thermo gasket and will test again when I don't have a cop right behind me😉
Mountain Pass
Joined: Mar 2016
Posts: 126
Likes: 7
From: Quesnel, "BC"
I would be getting a good heat gun and take readings of radiator( top and bottom) you must use same point on top as you do on bottom.
i.e.- if you point it at top rad hose ( close to tank) you must point it at lower hose, close to tank. If tanks are easiest , you must use both tanks.
get truck(engine) as hot as possible, take gun and take readings( should have about 10 deg difference top to bottom) , you can rule out rad as problem.
if it’s almost the same, rad is plugged externally , if there is way more than 10 deg difference, rad is plugged internally.
Remember safety - trans in park and ebrake or chock wheels, and everything very hot!!
just saying!
i.e.- if you point it at top rad hose ( close to tank) you must point it at lower hose, close to tank. If tanks are easiest , you must use both tanks.
get truck(engine) as hot as possible, take gun and take readings( should have about 10 deg difference top to bottom) , you can rule out rad as problem.
if it’s almost the same, rad is plugged externally , if there is way more than 10 deg difference, rad is plugged internally.
Remember safety - trans in park and ebrake or chock wheels, and everything very hot!!
just saying!
1st Gear
Joined: Apr 2024
Posts: 1
Likes: 0
Same issue
I have a 1996 7.3 power diesel bus and having this same issue. Did you ever get this figured out? It only begins to overheat when it is hot outside 75 degrees or more and at highway speeds but this happens for me also when idling with the A/C on. I’m learning as I go and I don’t know what to check first. My wife wants me to just start replacing parts, but I would like to actually grasp what the issue is before I do so.
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