Running Hot!
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Joined: Jun 2007
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Running Hot!
New to the fourm and thought I could get some help with a problem I am having. I recently purchased a 78 F150 2wd 351M. I am the second owner. Lady I bought it from put 2000 miles on it since 1997.
The truck seems to run hot all the time, but has never boiled over. The farthest I have driven was about 20miles and the gauge stayed in the high side of the “normal” range the whole time. (it stayed pinned on the “L” in normal most of the trip)
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I have flushed the system and installed new 190 thermostat, and new hoses, but it still runs hot. No leaks anywhere to be found. Engine does not smoke and oil looks good.
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Is there any way to check that the radiator is functioning properly, and not clogged?
Thanks!
The truck seems to run hot all the time, but has never boiled over. The farthest I have driven was about 20miles and the gauge stayed in the high side of the “normal” range the whole time. (it stayed pinned on the “L” in normal most of the trip)
ffice
ffice" /><O></O>I have flushed the system and installed new 190 thermostat, and new hoses, but it still runs hot. No leaks anywhere to be found. Engine does not smoke and oil looks good.
<O
></O>Is there any way to check that the radiator is functioning properly, and not clogged?
Thanks!
Post Fiend
Joined: Jul 2006
Posts: 6,948
Likes: 44
Welcome to the site.
If you can't find the answer to your question here, the answer does not exist.
Anyway, you might first verify that the gauge is not just off. It could be telling you it is hot, or above normal, and not really be that hot. You can use a thermometer for food, like a candy thermometer, and verify the operating temp with the cap removed. Remove the cap before it reaches temp. or you could burn yourself so use caution.
I think you might find that the truck may be running at a normal temp.
If you verify that the engine temp is too high, you can make sure that the fan, and shroud are in good working order. Water flow is important, do make sure that water can flow throuh the radiator properly.
That should get you started. Good luck..
If you can't find the answer to your question here, the answer does not exist.
Anyway, you might first verify that the gauge is not just off. It could be telling you it is hot, or above normal, and not really be that hot. You can use a thermometer for food, like a candy thermometer, and verify the operating temp with the cap removed. Remove the cap before it reaches temp. or you could burn yourself so use caution.
I think you might find that the truck may be running at a normal temp.
If you verify that the engine temp is too high, you can make sure that the fan, and shroud are in good working order. Water flow is important, do make sure that water can flow throuh the radiator properly.
That should get you started. Good luck..
Post Fiend
Joined: Jan 2003
Posts: 10,323
Likes: 2
From: Montana Territory
Try replacing the sending unit, its right on the front of the motor, you'll see a single wire going down to it, its on the passenger side of the motor, just below the thermostat housing. They run about $9.
Laughing Gas
Joined: Dec 2003
Posts: 1,062
Likes: 12
From: Ford, WA
my old 78 motorhome used to overheat alot.. replaced the radiator (4 row), and installed a 7 blade clutch fan (used to have a 5 blade direct drive flex fan) and it never ran hot again..could even run the A/C without it heating up..
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Thanks for all the help guys. Started with the easy stuff fist, radiator flush new thermostat & hoses. Was still running hot so I figured I would go a head a replace the radiator cap (13lb) since it was a little easy to squeeze, and that actually did help for a while. I guess a number of things cause the system to not be pressurized and when I installed the new cap it got pressured in a hurry. Saturday one whole side of the radiator blew and that was that.
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I installed a new radiator Saturday night and things seem to be ok. I am still going to install an aftermarket gauge that reads in degrees instead of the standard “C” –“H”.
<o></o>
After the new radiator the gauge is running about “1 o’clock”. Funny thing is, after starting and driving about 5 minutes, the gauge will go all the way to the “L” in normal and then creep back down and rest a little past the middle (1 ‘clock) . I’m assuming that’s an indication that the thermostat opened and cooled the engine down..??
<o></o>
Thanks again for the help, I’m sure you’ll see me post more and more as I get to know this old truck.
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
fficeffice" /><o></o>I installed a new radiator Saturday night and things seem to be ok. I am still going to install an aftermarket gauge that reads in degrees instead of the standard “C” –“H”.
<o
></o>After the new radiator the gauge is running about “1 o’clock”. Funny thing is, after starting and driving about 5 minutes, the gauge will go all the way to the “L” in normal and then creep back down and rest a little past the middle (1 ‘clock) . I’m assuming that’s an indication that the thermostat opened and cooled the engine down..??
<o
></o>Thanks again for the help, I’m sure you’ll see me post more and more as I get to know this old truck.
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Post Fiend
Joined: Jan 2003
Posts: 10,323
Likes: 2
From: Montana Territory
Yep... thats pretty normal function. 
good work with a process of elimination and starting with cheaper stuff. This time it ended up being a radiator, but better than starting with the radiator and it being a cap...
good work with a process of elimination and starting with cheaper stuff. This time it ended up being a radiator, but better than starting with the radiator and it being a cap...
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