390 overhreating
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New User
Joined: Jan 2009
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390 overhreating
I have a 73 f250 that was given to me from my dad . The motor only has 70k on the original motor. It has been having problems overheating. This happens when just driving not pulling a loading need some suggestions on what I should check first. I believe the oil pump was changed, what that had to do with overheating I am not familiar with. The thermostate was also messed with. They took it out and it still overheated, so they put it back in.I know I am not giving much but this one is stumping me.
Fleet Owner
Joined: Sep 2005
Posts: 28,609
Likes: 18
From: Lake Tahoe, Nevada
You need three things:
1. Good circulation, meaning that the radiator must be clean enough for good coolant flow and the thermostat must open. The belt must be driving the water pump. Also the block must be clear and clean enough inside to allow good flow and heat transfer from the motor to the coolant.
2. Good airflow. The fan has to turn, the fan clutch (if any) has to engage when hot. And the radiator must be clear of obstructions such as mud, paper, leaves etc.
3. Adequate coolant. If the truck is loosing coolant, that would suggest a leak or coolant being displaced by an engine fault such as combustion gasses leaking into the cooling system.
1. Good circulation, meaning that the radiator must be clean enough for good coolant flow and the thermostat must open. The belt must be driving the water pump. Also the block must be clear and clean enough inside to allow good flow and heat transfer from the motor to the coolant.
2. Good airflow. The fan has to turn, the fan clutch (if any) has to engage when hot. And the radiator must be clear of obstructions such as mud, paper, leaves etc.
3. Adequate coolant. If the truck is loosing coolant, that would suggest a leak or coolant being displaced by an engine fault such as combustion gasses leaking into the cooling system.
Laughing Gas
Joined: Jan 2007
Posts: 868
Likes: 2
put in a new thermo (195),they are like eight dollars. If it has fan clutch, listen to ensure it's engaging. Barring obviously low coolant levels, it sounds like a plugged radiator. Beings its cheap, pull it out and have a rad shop boil it out. It shouldn't cost more than about 30-50 dollars.
cheers
cheers
Junior User
Joined: Jun 2003
Posts: 96
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From: North Carolina
I had the same problem with my 76. I flushed the radiator, changed the thermostat, changed all the belts and hoses, new water pump, and it still over heated. I finally bought a new radiator and it still over heated. I brought it to a friend of mine who is a mechanic and he told me to check my water pump. I told him it was new and he said check it again anyway.
I felt like I was wasting my time, but I went ahead and took the water pump off and guess what.......the impeller fell out. It was a faulty pump, so I replaced it and so far no problems.
I felt like I was wasting my time, but I went ahead and took the water pump off and guess what.......the impeller fell out. It was a faulty pump, so I replaced it and so far no problems.
Postmaster
Joined: Aug 2005
Posts: 2,760
Likes: 8
From: Gadsden Purchase
...a mechanic and he told me to check my water pump.
I told him it was new and he said check it again anyway.
I felt like I was wasting my time, but I went ahead and took
the water pump off and guess what.......the impeller fell out.
It was a faulty pump, so I replaced it and so far no problems.
I told him it was new and he said check it again anyway.
I felt like I was wasting my time, but I went ahead and took
the water pump off and guess what.......the impeller fell out.
It was a faulty pump, so I replaced it and so far no problems.
Mine was getting hot while sitting, would have to rev it up at lights.
Everything was new and/or real good. 360FE T18 PS
Bumped the timing up to ~10 degrees BTDC and fixed it.
I know Montie's symptoms are different, so may not help at all, but
it is cheap and easy. ;)
I'm not so sure taking the thermostat clean out and it still got hot,
-proves- anything at all. :/
Did it get hot different?
Less?
More?
Quicker?
Slower?
Could be dirty carburetor problems.
Lean conditions.
These threads go on forever and a lot of the reason is it's just something
the guy on the ground ends up having to figure out. :/
What's it look like in the radiator?
Clean?
Got stuff stuck all over the inside?
What's it feel like when the belt is off the water pump?
Alvin in AZ
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Senior User
Joined: Feb 2005
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Dont know what to really say but my 73 f250 4x4 390 is doing the same thing I can even see the coolant criculating with the cap off. doesnt smell like it is overheating has never boiled over so I came to the conculsion it is the crummy 35 year old gauge in the dash everything else under the hood is new.
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That's a good point, how are you verifying it's overheating, the dash guage?
My dash guage has literally been all over the place, when in fact it has held a steady temperature. Kind of freaks you out seeing the dash gauge pegged on high and then look at the mechanical guage it's at 182.
Just saying...
Josh
My dash guage has literally been all over the place, when in fact it has held a steady temperature. Kind of freaks you out seeing the dash gauge pegged on high and then look at the mechanical guage it's at 182.
Just saying...
Josh