Possible Therostat Stuck
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Tuned
Joined: Nov 2006
Posts: 455
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Possible Therostat Stuck
I’ve got an 02 F150 supercrew with the 5.4. A couple weeks ago, while towing my boat, when I tried to jump on the highway the temp shot up. Had to get on the Service road and run the heater to get the temp back to normal. Got home checked the coolant, added a little. Then never did it again. Until today. Same thing, jumped on the highway while towing the boat, temp shot up. Got it to get back to normal the same way. On the way home, driving slow, temp was close moving again by the time I got home. Does this sound like it could be the thermostat sticking closed?
Fleet Owner
Joined: Apr 2008
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From: 0,0,1
Could be the t-stat sticking, the radiator could be partially clogged, the fan clutch could be slipping, or the water pump could have a broken impeller. It's hard to take a guess based solely on "the temp shot up."
Cross-Country
Joined: Dec 2017
Posts: 84
Likes: 8
From: Fairbanks Alaska
Given the low cost, I'd suggest putting in a new thermostat if for no other reason than to rule it out. I replace mine when I change the coolant to hopefully avoid a thermostat problem during the time I own the vehicle. Because it only happens when you're towing, I'm thinking it might just be some other more pricey problem, but putting in a new thermostat would at least rule that out.
Hotshot
Joined: Jul 2005
Posts: 11,931
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If it ONLY does it when your pulling the boat, then it might be load related.. Put a BIG LOAD on the truck and it gets hot. That would lead me to believe the radiator is partly plugged inside or outside. Might be a good time to FLUSH the inside out and change fluid......... and was external fins / coils with a garden hose........... nothing blocking air flow thru front end ??
Fleet Mechanic
Joined: Aug 2008
Posts: 1,446
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From: NE Iowa JD Country
If it ONLY does it when your pulling the boat, then it might be load related.. Put a BIG LOAD on the truck and it gets hot. That would lead me to believe the radiator is partly plugged inside or outside. Might be a good time to FLUSH the inside out and change fluid......... and was external fins / coils with a garden hose........... nothing blocking air flow thru front end ??
You also might have a external transmission cooler that could also be restricted. When was the last time you changed out your transmission fluid and filter?
Fleet Owner
Joined: Apr 2008
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From: 0,0,1
Nothing you would ever hear over the sound of the engine. But for now like others have pointed out already, your issue seems to be related to moments of heavy engine load. This is indicative of the radiator not being able to dissipate the heat fast enough or a weak coolant flow. If the radiator is original then it's 16 years old.
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Lead Driver
Joined: Sep 2006
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A partially blocked radiator loses cooling ability under higher heat loads.
Acts like a radiator that is too small for cooling area.
If the coolant is dirty and a lot of stain in the jug, it may be the cause has just caught up.
That would indicate the antifreeze has not been changed often enough over the life of the truck.
Good luck.
Acts like a radiator that is too small for cooling area.
If the coolant is dirty and a lot of stain in the jug, it may be the cause has just caught up.
That would indicate the antifreeze has not been changed often enough over the life of the truck.
Good luck.
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Tuned
Joined: Nov 2006
Posts: 455
Likes: 2
Ok. I just now got around to reading the “new” replies. I actually ended up blowing a head gasket shortly after I had the over heating problem. Did the head gaskets and actually forgot about the heat. Until today. Funny, exact same thing. Got hot while pulling the boat. I’ll probably go ahead and do a coolant flush and replace the radiator.
Thanks for all the help.
Thanks for all the help.
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