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Closed to Open Cooling question (turning on the efan)


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You can just plug it with the proper size npt brass plug.  Makes purging the air easy as well that way.  With the engine cold remove the plug when you are filling with coolant and put the plug back in when coolant starts to come out of the hole.  Make sure the heater valve is open.  You're already wired through the block and the head.

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  • 1 year later...
On ‎12‎/‎27‎/‎2018 at 11:14 AM, Ωhm said:

Two questions, 1.) Do you have a temp gauge or idiot light in the cluster? 2.) Are your sending units for a temp gauge or idiot light?

I am bringing this one back up. Answers 1) had a light now have a gauge  2) Sending unit has been swapped for a gauge

 

 

On ‎12‎/‎27‎/‎2018 at 12:11 PM, Pete M said:

do you mean "closed to open"?

 

Yes.

 

On ‎12‎/‎27‎/‎2018 at 12:34 PM, Eagle said:

Why are you changing the thermostat housing?

 

My truck is a non AC truck and does not have an E-fan but I want to add one. The later model thermostat housings have a switch in them that can be used to turn on an E-fan once a certain temp is reached...as I understand it.

 

Couple questions:

 

The switch has two wires. One wire, not sure what color wire though, needs a power wire that comes from ignition. Second wire then would feed a relay that in turn would power the fan. Yes? No?

 

At what temp does the switch trigger the relay?

 

Thanks!

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16 minutes ago, High2by said:

At what temp does the switch trigger the relay?

 

My e-fan does not kick on until the engine temp reaches 219*.  That temp comes off the REM scanner which takes the temp from the engine block.  The e-fan temp switch draws from the cool side of the radiator.  So, I would guess that the coolant temp is a lot lower than 219* at that location.

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4 minutes ago, 87MJTIM said:

My e-fan does not kick on until the engine temp reaches 219*.  That temp comes off the REM scanner which takes the temp from the engine block.  The e-fan temp switch draws from the cool side of the radiator.  So, I would guess that the coolant temp is a lot lower than 219* at that location.

 

Am I thinking right though that I can use that switch in the thermostat housing to do what I need?

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Just now, 87MJTIM said:

:dunno: You will need to determine which wires are in place to run the fan.

 

I don't think there are any wires already in place, heck I don't even think the relay is there but I can run all new wiring if what I'm suggesting will work.

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The problem is that the t-stat housing sender is for the HO, and it uses the computer to control the aux fan. The Renix models controlled the aux fan with a switch in the driver's side radiator tank that fed a relay on the driver's side inner fender. You can certainly ue a sender in the t-stat housing, but you need to find one that's an ON-OFF switch, not a sender. Reports from years past were that there was a Corvette sender/switch that worked at the right temperature, but I have no idea what part number to look for.

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The problem is that the t-stat housing sender is for the HO, and it uses the computer to control the aux fan. The Renix models controlled the aux fan with a switch in the driver's side radiator tank that fed a relay on the driver's side inner fender. You can certainly ue a sender in the t-stat housing, but you need to find one that's an ON-OFF switch, not a sender. Reports from years past were that there was a Corvette sender/switch that worked at the right temperature, but I have no idea what part number to look for.


What would the difference be in the temperature at the t-stat housing vs the radiator location?

Any?

If there’s no difference would the Renix switch work in the t-stat housing?

I ask because the radiator that’s in the Jeep doesn’t have the bung for the switch.


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38 minutes ago, High2by said:

 


What would the difference be in the temperature at the t-stat housing vs the radiator location?

Any?

If there’s no difference would the Renix switch work in the t-stat housing?

I ask because the radiator that’s in the Jeep doesn’t have the bung for the switch.


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The temp coming out of the T-stat housing will be the hottest.  The temp on the cool side of the radiator will be much lower.  How much? IDK.

 

NAPA sells a radiator that is an open system but has a bung for a switch - NR 2802.

 

If  you have not downloaded the 88 electrical manual yet, you should do so.  It will assist with understanding the wiring for the e-fan.  

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17 hours ago, High2by said:


If there’s no difference would the Renix switch work in the t-stat housing?
 

 

 

The Renix switch is MUCH larger in diameter. Don't know the specs, but more than 1-inch in diameter. Definitely won't fit the t-stat housing.

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The temp coming out of the T-stat housing will be the hottest.  The temp on the cool side of the radiator will be much lower.  How much? IDK.
 
NAPA sells a radiator that is an open system but has a bung for a switch - NR 2802.
 
If  you have not downloaded the 88 electrical manual yet, you should do so.  It will assist with understanding the wiring for the e-fan.  


I hate to put in a new radiator but I would like for the e-fan to work without having a toggle switch in the cab.


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The temp coming out of the T-stat housing will be the hottest.  The temp on the cool side of the radiator will be much lower.  How much? IDK.
 
NAPA sells a radiator that is an open system but has a bung for a switch - NR 2802.
 
If  you have not downloaded the 88 electrical manual yet, you should do so.  It will assist with understanding the wiring for the e-fan.  


I hate to put in a new radiator but I would like for the e-fan to work without having a toggle switch in the cab.


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The Renix switch is MUCH larger in diameter. Don't know the specs, but more than 1-inch in diameter. Definitely won't fit the t-stat housing.


I actually found the renix switch today in an old radiator. Your right theres no way that thing is gonna fit in the housing.


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You could search for a switch with a probe that slots into the rad fins.  I don't know of one, but if you have this issue, most likely someone else has also.  Necessity is the mother of invention.


Good idea.


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One possible way of switching an efan.....  I installed an efan in my now open cooling system last spring.  To house the switch I installed an HO thermostat housing.  Rodney Dickman has two 3/8 npt switches, one is for a 195 degree thermostat.  On 210, off 200.  I used to have constant problems with high temps when slow steep towing or sitting in traffic for extended lengths of time.  I never overheat now under any conditions. 

 

http://rodneydickman.com/catalog/product_info.php?cPath=69&products_id=235

 

Wiring plan I used.

 

https://www.davebarton.com/pdf/coolingfandiagrams.pdf

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17 hours ago, rokinn said:

One possible way of switching an efan.....  I installed an efan in my now open cooling system last spring.  To house the switch I installed an HO thermostat housing.  Rodney Dickman has two 3/8 npt switches, one is for a 195 degree thermostat.  On 210, off 200.  I used to have constant problems with high temps when slow steep towing or sitting in traffic for extended lengths of time.  I never overheat now under any conditions. 

 

http://rodneydickman.com/catalog/product_info.php?cPath=69&products_id=235

 

Wiring plan I used.

 

https://www.davebarton.com/pdf/coolingfandiagrams.pdf

 

This looks like it will work and I wouldn't have to swap radiators. Thanks!!

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