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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

Radiator has 2 overflow outlets, why?

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Old Jan 21, 2010 | 02:43 PM
  #16  
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Just an update on this if anyone is interested.

I got a small piece of hose (probably leftovers from the parts yard) and clamped it on the second, unused, overflow outlet. I just plugged the other end with a piece of brass I had lying around and put a clamp on it as well. Worked great, thanks for the information on it.
 
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Old Nov 29, 2020 | 11:02 PM
  #17  
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Raising this from the dead. My 1985 F150 4.9 I6 has this "second" port just below the radiator cap.

I discovered it because when I over filled my coolant, it came pouring out on the ground.

Does anyone know what to plug it with? Do you seal it with a gasket sealer or something?


What scares me is I've been driving it with the hole unplugged since I've owned it.

My guess is some mechanic replaced the radiator and didn't realize there was another hole. That's what she said

 
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Old Nov 30, 2020 | 07:28 AM
  #18  
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Did you read the previous post to see what he did? Maybe there is a rubber cap in the “HELP” section at the parts store that will work. Every replacement radiator that have purchased came with a cap to block off that port if you didn’t use it in your application. Don’t forget to use a hose clamp. It is below the seal on the cap and is pressurized.
 
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Old Nov 30, 2020 | 09:51 AM
  #19  
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They sell a bypass cap assortment in the Help parts. That's what I used to plug mine.
 
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Old Dec 18, 2022 | 05:13 PM
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That’s where it goes now🤷‍♂️
 
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Old Dec 19, 2022 | 07:46 PM
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Originally Posted by StoneyLonesome

That’s where it goes now🤷‍♂️
I dont know why you revived this thread, but if you must know what its for, it T-s into the heater core line(not sure if it was inlet or outlet, I believe inlet...) and its purpose is to reduce gurgling noises and potentially help with flow. The noise I think was the primary. I dont think its really necessary, but thats what it does.

here is a 4.9 with the outlet, i think, to the heater core

 
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Old Dec 21, 2022 | 01:32 PM
  #22  
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I always thought you use the top one with an overflow tank or the bottom one with an expansion tank.
 
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Old Dec 21, 2022 | 01:34 PM
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Originally Posted by jtab
I always thought you use the top one with an overflow tank or the bottom one with an expansion tank.
that may be true somewhere but the function of expansion tank sometimes is the only thing on a vehicle, sometimes only overflow, sometimes both. depends on how its all setup. It is ostensibly just a place that allows coolant to return to the radiator the reason isnt really that huge. the top one is controlled by the cap spring/element which will expose or block the opening based on pressure
 
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Old Dec 21, 2022 | 05:30 PM
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Not on v8's that bottom port connects with a pipe, going all the way back to your throttle body, to keep it from icing up in cold weather.


 
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Old Dec 26, 2022 | 06:58 AM
  #25  
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The lower connection allows air to be purged from the system. It's easier to purge than trying to get the system to push the air through the heater core and back down through the water pump. Notice it connects to the highest hose in the cooling system.
 
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Old Dec 26, 2022 | 09:20 AM
  #26  
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Damn

Sure is a lot of discussion for a dead topic, huh?
 
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Old Dec 27, 2022 | 05:43 AM
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Originally Posted by StoneyLonesome
Sure is a lot of discussion for a dead topic, huh?
not at all, if you had read then you would have noticed that its a lot of discussion because it was in response to a recent inquiry.

now, it was not related to the OPs subject, however it was easy/simple enough that it didnt warrant making a thread about it since no one needed help
 
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