Electric fan switch temps and location

[JoshT]

Planning to do an electric fan conversion on my 99 Ranger 4.0L. I have already sourced a Taurus E-fan w/spare motor, as well as a Volvo 2-speed fan relay, and know how it needs to be wired. What I am having trouble wrapping my head around is the thermal switch(es) to control it.

For starters I have already swapped a 2 core Explorer V8 radiator into the truck. I didn't install it because the stock size radiator was not up to the task, but because I suspected the radiator it replaced of having problems (clogging and/or leaking) and I had this known good radiator on hand. Either spend $150+ for a new stock radiator, or install a larger radiator for free, I went with free. So with that addition my cooling system is more than up to the task of cooling the nearly stock 4.0L.

My plan is to install the e-fan temp switch in the lower radiator hose so that it is actually trying to control the temps of the coolant in the radiator, which is what a radiator fan is for. IMO installing the switch in the upper hose (or closer to the T-stat) it is trying to control the temps of coolant in the engine, which the radiator fan can't do. I want the radiator fan to run if the "natural" air flow through the radiator is not enough, not because the radiator got a fresh load of hot coolant which the radiator might be able to cool on it's own.

So I can get dual temp switches in a variety of temps, or I can get individual switches to control each speed in an even larger variety. Problem I'm having is what temp to run for each speed. What should my fan speed temps be for coolant leaving the radiator? I've seen that the Haden heavy duty clutch is designed to engage around 170 degrees radiator temp, would this be a good low speed fan setting for the E-fan? How much higher would I want the high switch to be set?

Pulling the engine next week to fix a leak around rear main. I'm not quite ready to install the fan yet but while I have the system drained I would like to go ahead and install my hose adapter and switch, got to figure out which switches to get so I know which adapter to order.

 

[JoshT]

Just noticed I managed to post this in the wrong section. Meant to put it in the "Under the Hood" forum. Sorry!

 

[jd4242]

What tstat are you running? I dont use the lower speed on mine, just high.on is set to 185 and off at 175* and I run a 180* tstat..I also plan to relocate my switch to the lower hose, actually just order a fitting yesterday. Mine currently is in the upper heater hose and like you said it trys and control the engine temp not radiator temps.it kicks on I feel a little early and also doesnt kick off when it should.the tstat is keeping the water in the motor around 180* which is what my sensors reading and doesnt kick the fan off.the water in the radiator is well below the 175* kick off but the senor is reading the engine temp..

For stock temps I would set the high to kick on at 190-195 and low around 180-190.most sensors kick off 10* before kick on so dont set the on to low or the kick off will be to low and probably run all the time

 

[JoshT]

Running a 195° stock replacement, meant to mention that in the first post.

 

[JoshT]

I've found several switches from VW and BMW that might be good fan switch options. Biggest issues with these switches is the thread size which I think I have found a solution for, more on that later.

The switches:

switch
Low: on-off / High: on-off (°c)
Low: on-off / High: on-off (°f)
Thread size
P/N: x.. x.. (manuf.)

VW high range switch
95-81/102-91 (°c)
203-178/215-196 (°f)
m22x1.5
P/N: 191959481c (Wahler)

BMW high range
91-86/99-94 (°c)
196-187/210-201 (°f)
m14x1.5
P/N: not available will add later

VW mid range switch
85-74/93-82 (°c)
185-165/199-180 (°f)
m22x1.5
P/N: 251959481k (Wahler)

BMW low range switch
80-75/90-85 (°c)
175-167/194-185 (°f)
m14x1.5
P/N: not available will add later

VW low range switch
75-70/82-77 (°c)
167-158/180-170 (°f)
m22x1.5
P/N: 25195948175 (Wahler)

Looking at most of the vehicles that use these sensors the switch temp is actually higher than the t-stat temp and the switch is in the radiator. With putting my switch in the lower hose not sure I agree with a higher switch, but it does make me think I can go higher temp than in thought I needed. Will probably start with that mid range VW switch. From there if the fan runs too often, or too little, I can move to the appropriate BMW switch.

As for the adapter I found a place that will make a rad hose adapter with both a m22 port and a 3/8 NPT port, and I can get an adapter to run the m14 switch in the 3/8 port. I should also be able to get or make an adapter to put the m14 switch in the m22 port which would leave the 3/8 port open for nearly any other sensor.

 

[jd4242]

Yea normally you want it set at or slightly above the tstat.remember the ohv doesnt like heat though and being your in George I would like it to run a little cooler, i would lower your tstat some to like 185-190*..the ohv really shouldnt get much over 200* for normal use,210-220* and its toast.the heads are too prone to crack.

 

[JoshT]

My main issue with that is I thought the engine needed to be in the 190-195 range for the EFI system. I do see that motorcraft offers a 190° unit that may be an option. I also see a 192° from motorad which is the exact temp I've seen for the EFI system.

 

[jd4242]

My main issue with that is I thought the engine needed to be in the 190-195 range for the EFI system. I do see that motorcraft offers a 190° unit that may be an option. I also see a 192° from motorad which is the exact temp I've seen for the EFI system.

As far as I know it has nothing to do with efi..the pcm is programmed to run in closed loop (think may have it backwards) till the motor reaches a set temp or runs for I belive is 15mins.after that happens it doesnt matter what temp it runs at (reasonable temp) newer motors are made to run at higher temps but they are made that way to be more efficient/better mpg. They are also made to run leaner (hotter air/temps normally causes that) thinner oil, etc etc.

The ohv isnt made for that, its still a old school motor design with poor oiling and weak heads.the cooler the better (within reason)

 

[JoshT]

Found the t-stat box where I replaced it when doing the water pump. I was wrong about temp it is a 192° Murray Ultrastat, which is a Motorad High Flow stat in a different box.

If I could find a 185° I'd get one asap, but all I can find are 180°, 190°, 192°+ ratings. Still concerned about 180° being too low temp and affecting the way the truck runs. I understand that at lower temps you gain power, but loose efficiency. Can the stock tuning handle the change in operating temps? How much will it affect fuel efficiency? Too much change in efficiency negates one of the benefits of an electric fan. If the 12° drop won't affect it too much then I may get the 180° stat.

Is lower operating temp and electric fan something I should have adjusted for when I get a custom tune for the truck? Wouldn't get a tune just for it, but I have other reasons for the tune.

 

[jd4242]

Dont get me wrong a 192* is just fine.just being kind of down south a little lower temp is kind of a safe net.your really notice no difference in mpg or efficient with this old of a vehicle. Its just in my opinion a way to help prevent damage to a heat prone motor, keeping the motor and trans a little cooler may help extend the life especially on those HOT days or climate.

Keep in mind though where we are talking about putting the sensor its going to be slightly behind the 8ball when it comes to cooling.meaning if you have it set to 190 entering the engine (radiator water output) that the water coming out the motor is going to be ABOVE 190* and the fan is going to take a bit to get the water down to below 190* so your motor may spike to 200*+ before the water coming in is below 190*

I honestly dont know if there is a way to change the temp on the tune with a obd1.there isn't alot of things you can adjust.dont think mine was changed when I had mine tuned.tuning is VERY expensive and typically not needed unless you go forced induction. Sure it would help but not worth the cost on a NA motor.

Sure others will chime in with there opinion on where they have their fans set to, most ive seen is around 190 tho

 

[jd4242]

Sorry just seen yours is a 99.yes it can be tuned for a lower temp.its just a matter of when it enters or exits closed/open loop.but as far as I know it becomes irrelevant after so many minutes of running

You also have 98tm heads that are less prone to cracking and heat..so going to a lower temp would be just a more so of a preference call

 

[JoshT]

Just to clarify a little is is a 1999 so OBD-II and EEC-V. As for age the truck is 15, but the motor has about 650 miles in it and the trans is around 20k on rebuild. Mild cam added at rebuild, also plan to do exhaust and maybe intake work. OBD-II is cheaper to tune from what I read and will be worth it for shift adjustment and speedo correction alone. Heck my last speeding ticket would have paid for it.

Heads are also aftermarket cast 98tm.

 

[jd4242]

Just to clarify a little is is a 1999 so OBD-II and EEC-V. As for age the truck is 15, but the motor has about 650 miles in it and the trans is around 20k on rebuild. Mild cam added at rebuild, also plan to do exhaust and maybe intake work. OBD-II is cheaper to tune from what I read and will be worth it for shift adjustment and speedo correction alone. Heck my last speeding ticket would have paid for it.

Heads are also aftermarket cast 98tm.

Yea thats my fault man.I over looked it in your first post

 

[JoshT]

It happens, still appreciate the help you've been giving. I think I'll stay with the 192 for now. When tuning happens I think I'll use the guy in Alabama, I think it is Henson. Of he recommends the 180 I'll switch.

Not ready to put the fan in yet, so I'll get a switch appropriate for the 192. Wire it to indicator lights so i can watch its operation. Then I'll put a coolant temp gauge and watch what temps it comes on and adjust as needed.

 

[jd4242]

It happens, still appreciate the help you've been giving. I think I'll stay with the 192 for now. When tuning happens I think I'll use the guy in Alabama, I think it is Henson. Of he recommends the 180 I'll switch.

Not ready to put the fan in yet, so I'll get a switch appropriate for the 192. Wire it to indicator lights so i can watch its operation. Then I'll put a coolant temp gauge and watch what temps it comes on and adjust as needed.

Yea think 192 will be fine in your case.yea his name is James

Let me know what you find out as far as when it kicks on compared to engine temps.my adaptor should be in next week or so and ill be moving mine to the lower hose.I got the adapter from ebay, fyi.

 

[JoshT]

I got the adapter from ebay, fyi.

Do you have a link to the one you bought?

 

[jd4242]

I believe it was this one.I run a v8 swap radiator and only the ""hi"" setting on the fan tho.they carry a bunch of them in different sizes, may even have a dual sensor one.

http://www.ebay.com/itm/300871503368?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649