Experience with 180* thermostat with 4.0L

[Gjeep]

I got my Digital Dakota fan controller installed and it works great though it was a real pain to program at first. I'm currently running a 195* stock Mopar t-stat in my 4.6L stroker. My dual electric fan set up comes on about 5* too hot/ late on the low setting. And I can't program the Dakota Digital controller any lower than 150*. My MJ is a '92 H.O, but my H.O radiator is set up with the Renix port so I'm putting it to use...The reason the fans are coming on 5* late is because where the temp sensor is in the Renix-era port of the radiator doesn't get hot coolant until the 195* t-stat opens then it kicks on once temp setting is reached. This won't be a problem when driving I know, but when idling I'm at 215*. Not terrible, but I want it idling at 210*. That's why I'm considering trying a 180* thermostat and then I can raise the fan controller temp turn-on a bit... Just curious if anyone has run a 180* t-stat in their 4.0L and any feedback. Thanks.

[jeeptec1]

My experience is the heater doesn’t have as much heat as with a 195. A Renix area seems to run ok. The Chrysler area seem to run a little rich and have had one that caused a check engine light for a thermostat Code.


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[Eagle]

2 hours ago, Gjeep said:

I got my Digital Dakota fan controller installed and it works great though it was a real pain to program at first. I'm currently running a 195* stock Mopar t-stat in my 4.6L stroker. My dual electric fan set up comes on about 5* too hot/ late on the low setting. And I can't program the Dakota Digital controller any lower than 150*. My MJ is a '92 H.O, but my H.O radiator is set up with the Renix port so I'm putting it to use...The reason the fans are coming on 5* late is because where the temp sensor is in the Renix-era port of the radiator doesn't get hot coolant until the 195* t-stat opens then it kicks on once temp setting is reached. This won't be a problem when driving I know, but when idling I'm at 215*. Not terrible, but I want it idling at 210*. That's why I'm considering trying a 180* thermostat and then I can raise the fan controller temp turn-on a bit... Just curious if anyone has run a 180* t-stat in their 4.0L and any feedback. Thanks.

 

It won't make any difference. The purpose of a thermostat is to keep the temperature UP, not down. If it idles at 215 with a 195 degree thermostat, it will idle at 215 with a 180 degree thermostat.

[Gjeep]

I don’t see how. Since the fans would come on sooner. Right?

[jdog]

Why not move the fan switch to another location?

When do the fans kick on now?

Also, what is it running at when moving?

 

 

 

[Gjeep]

Yep moving the temp sender would be the quickest fix but my stubborn self wants to use the renix port. 

 

Thinking that a 180* t-stat would keep the coolant cooler and actually take the temp sensor longer to kick on. Think I'm going to stay with the 195* and see how it goes. Should be fine I think.  Thanks all.

[Ωhm]

10 hours ago, Eagle said:

If it idles at 215 with a 195 degree thermostat, it will idle at 215 with a 180 degree thermostat.

His fans are inadequate for his needs (210°).

 

8 hours ago, Gjeep said:

I don’t see how. Since the fans would come on sooner. Right?

Wrong

 

3 hours ago, Gjeep said:

Thinking that a 180* t-stat would keep the coolant cooler and actually take the temp sensor longer to kick on

True, for awhile. Once engine block heats up, its all up to the fans.

[yxmj]

Try putting your fan trigger switch in your lower return rad hose. There are splice pipes with bungs out there to buy or one can fab up their own easy.

[AZJeff]

I have been down this road with SEVERAL vehicles, so here is my $0.02:

 

1.  Eagle is correct in that a thermostat controls the MINIMUM temperature the engine will see when warmed up, NOT the maximum temperature.

2.  The maximum temperature is governed by radiator size and/or air flow rate across the rad.   That is, of course, a function of the size/number of fans being used.

3.  If you want the fan to come on at a lower temperature, you either need to select a different temperature sensor to fit the Renix sized port.  Otherwise, putting a temperature sensor in-line on the UPPER radiator hose is the best way to control when an electric fan turns on.   WHy the upper hose?   Because that is the temperature of the HOTTEST water going to the radiator, and you are trying to control the HOTTEST coolant temperature.

[ghetdjc320]

I put my temp sensor in the upper heater hose and it also work well there since that’s on a tstat bypass

[Eagle]

17 hours ago, Gjeep said:

I don’t see how. Since the fans would come on sooner. Right?

 

But the coolant at the port will be 15 degrees cooler.

[Gjeep]

Thanks all -- confident my current set up should be fine. I was only idling for maybe 5 mins in the driveway. The fans I believe would have brought the temp down if I let it idle for longer. If that's not the case once I'm driving the MJ, then I'll be going to Hesco high-flow t-stat with 1/8" NPT port in front for my Fan controller temp sensor. 

 

[yxmj]

To reply to the post above…..

 

Yes this has been gone over and here again....and again.....  the error is putting the sensor in the hottest part of the water flow before the rad….if placed after the T-stat or in the upper hose before the rad, once the motor reaches operating temp, the fan will turn on and run constantly.

 

If anyone can disprove this with hard facts, then please do. My proof is below, I got the Idea from Hornbrod who used this location on his stroker successfully for years

 

For the sake of this description we are going to remove the mechanical fan and replace it with one single electric fan (I use stock XJ/MJ fans but an aftermarket will be the same).

 

We will assume a working 195° T-stat and a 195° N/O switch. And a moving truck.

 

First we install the temp switch in the T stat housing or upper rad hose…….we drive and run the truck up to temp……Stat opens @ 195 and allows fluid to flow…Motor will heat the coolant beyond the 195° point ….switch closed completes the circuit and turns the fan on…..fan will stay on constantly as long as the motor is running now….it will only shut off when the motor is shut off and cools down.

 

Now we install the switch in the lower (return) rad hose as described. Motor is run up to temp….Stat opens at 195° and allows the fluid to flow…..water pump does its job and pumps the water through the rad and out the return hose past the switch….If the act of the water running through the rad with just the air flow of movement drops the temp below 195 ( as much as 60° ) the switch will not close and the fan will not turn on…..BECAUSE IT DOES NOT HAVE TO……so you now get the benefit of removing the mechanical fan (I do not have the numbers on HP or MPG gain but it would obviously be something as the motor is no longer working to turn the Mechanical fan or in the case of the constantly running electric fan the extra load on the alternator.)

 

And like I said at 60 MPH….my fans do not turn on even when the temps are in the 90’s

 

Should the coolant in the return line be above the 195° mark the switch would close complete the circuit and turn the fan on until such time as the Temp should drop back down to the 195.

 

And before any one asks this one…..A 195° T-stat does not mean you motor is constantly running at 195°…..they run hotter than that …..195° is just the temp that the stat opens up and allows full circulation of the coolant.

 

There are other high end car manufacturers that place the switch in the lower hose from the factory

 

https://jeep-manual.ru/index.php?page=100

https://www.wranglerforum.com/f210/anyone-running-electric-fans-sensor-questions-1928378.html

https://grassrootsmotorsports.com/forum/grm/cooling-fan-sensor/39133/page1/

https://forums.corral.net/forums/general-mustang-tech/288712-electric-fan-those-who-put-temp-switch-lower-radiator-hose-inside.html

http://forums.turbobricks.com/showthread.php?t=270950

https://www.dieselplace.com/forum/63-gm-diesel-engines/20-6-2l-diesel-engine/829130-electric-radiator-fan-sensor-temp-lower-hose.html

http://www.fuelly.com/forums/f10/coolant-fan-temperature-switch-5252.html

[benjy_26]

If you want your engine to run cooler, use more water/less coolant and throw a bottle of Red Line Water Wetter in there.