Electric radiator cooling fan mod

[Paulos]

The last couple of days I've been thinking about actually doing the electric fan mod on my Ranger, but I wanted to get some opinions on a couple issues I haven't been able to figure out yet. I've kept an eye on this 2.9 forum for a while now, so I know I'll probably get a variety of answers . And putting in a 4.0 is not an option (even though I'm already using the radiator and hoses for one).

A year or so ago I read about using an Volvo electric cooling fan to replace the stock fan/fan clutch/fan shroud on the 2.9. I bought two slightly different Volvo fans with the wiring harness' (the price was right), a couple spare relay assemblies, high/low BMW temperature switches (both the 80/88C and 91/99C), a 30A circuit breaker, new upper and lower radiator hoses, etc.

The main issue is where to put the temp switch. I have read that most people put it in the upper/inlet hose, and some in the lower/outlet hose. When I was looking for Volvo fans and temp switches at the local Pick-a-part, I noticed that the BMW radiators (that the switches are made for) had the temp switch mounted towards the top of the outlet side of the radiator, which made more sense to me than installing it in either hose. I figure that the switch controls the cooling fan, which cools the coolant in the radiator; so it makes sense that installing the switch in either hose would not turn on/off the cooling fan at the proper time. The 4.0 radiator has a flat spot in the plastic tank on the outlet side where a bung for the temp switch can be added, but that would make it necessary to take the radiator to a shop to see if they can remove the tank to install the bung. A lot of hassle and expense.

So, has anyone done the radiator fan mod to their 2.9, and if so, where did you put the switch? Which temperature combination of switch and thermostat did you use? And most important of all, does the fan cool the coolant in the radiator efficiently (running long enough to properly cool it, but not running when it shouldn't be). Or if you haven't done it, just let me know what you think. And again, no 4.0 . But a 302 would be nice.

 

[88workcar]

I did my 3.0 late week, I will never go back lol. I felt a increase in power and see 2.5 MPG more. I am on the key switch to the relay, my temp switch adaptor has not arrived yet

 

[Paulos]

Where do you plan on installing the temp switch, the upper hose?

 

[Curious Hound]

I did it and I have messed around with the configuration a bit. I am currently running mine with the switch in the lower radiator hose. I may be using the switch with the lower settings. Can’t recall positively. I am also using a double row radiator, a 190 or mid 180’s thermostat and, since my used Volvo fan seemed to be dying, I bought a brand new fan. Don’t have the fan info handy right now. I started with the switch in the upper radiator hose. But didn’t like the way that worked. I have also tried several different thermostats. The current combination is what seems to be working best for me. Your experience might be different.

I felt like the fan was running way too much with the switch in the upper hose. My though on that is that it’s a high point and hotter Coolant may tend to stay there when the thermostat closes. In the bottom hose, I am controlling the fan based on what is returning to the engine from the radiator and when the thermostat closes, it will see cooler water and not run the fan until flow is restored by the thermostat.

Those are just my thoughts and opinions. I might be stupid. And many people have different ideas and experiences.

I refuse to claim any power gains.

 

[Paulos]

@ericbphoto
I was thinking about the same thing regarding the upper hose. I realize that as the coolant in the radiator cools, it will/should spread to the upper hose area also; but when it's hot out (like it is now), I doubt the t-stat would stay closed long enough for that to happen. I thought that maybe the lower hose location would do the opposite of the upper hose location. Ideally, I'm thinking that the outlet side of the radiator would be best; I was hoping that there was a way to put a bung in without dismantling the radiator.

Maybe I'll experiment with the lower hose also, and use manual override switches just in case. I found a good wiring diagram on another forum that I'll use to wire a couple of LED rocker switches.

 

[Paulos]

After looking at that wiring diagram I attached, it seems that it's wrong. The low speed and high speed bypass switches should not be "to switched hot" as indicated, as the temp switch is only supplying a ground for high or low speed. The rocker switches should also supply a ground, not 12v positive/hot. Something else to check out .

 

[gaz]

Paulos,

I have done this to both my 2.9's. On my 87 Ranger I control power to the fan manually in the cab with a toggle. I have learned that I never need the fan on, unless driving slower than 35 mph, in traffic or occasionally in the summer. If my temp hits 180, I flip the switch. It uses a 180 Tstat with Hyperchips stage II chip and a single 18" fan.

In my BII I went a different route. I used a thermostat controlled switch and I placed the sensor in the radiator fins on the driver's side near the inlet to the radiator. I set it to 180 as it has a 180 Tstat for the aftermarket PCM chip. (Jet stage II). Works great on a dual core Explorer radiator with single 18" puller.

 

[Curious Hound]

I'll look at that diagram later when I get a chance. I did my own with regular relays.

I'm curious why you want to introduce a potential leak point on your radiator instead of putting the switch in the hose. You're only talking about a few inches of distance from the one location to the other. And how do you think someone is going to reliably install an aftermarket bung on the plastic radiator tank? If you really want it there, it would be much better to have a radiator with aluminum tanks that a bung could be welded onto.

 

[Paulos]

@gaz
Yes, I have seen the temperature probes you mentioned, and that would be easier than putting a bung in the radiator. Not to mention, that the "URO" made BMW temperature switch I bought was defective, so I'm not impressed with the quality of them so far. I'll look into the temp probe a bit more. Thanks for your input. How about the source of those rocker spacer kits?

 

[Paulos]

@ericbphoto
As I mentioned in my first post, the whole point is the proper placement of the temp switch. It doesn't matter if I introduce a potential point of leakage, as the complete cooling system is already full of potential points where it can leak. If it's done correctly, it won't leak. I figure that the BMW engineers knew more about the proper placement of the temperature controlled cooling fan switch than I do, so they must have had a good reason for putting it there, and not in one of the hoses (which would have been far easier, and probably cheaper). And since I may be using one, I thought it might be a good idea to put it where they designed it to be. Just a thought.

The 4.0 radiator I have has auto trans cooling lines in the plastic tank. They are essentially the exact same thing I am talking about as far as a bung is concerned. The cooling coils are mounted from the inside of the tank with a rubber seal, and a lock nut of some sort on the outside of the tank. The same thing can be done for the temp switch, or just remove the trans cooler coils, plug the lower hole, and install the bung for the switch in the upper hole. Like I said, if it's done correctly it wouldn't be a problem.

I have considered just getting a new radiator (the one I have now is 6 years old) and have it modded at a radiator shop and pressure tested before installing it. I would probably do as you have first just to see if it will be worth the trouble and expense. And, like you mentioned, I have considered an aluminum radiator. And if my Ranger was anything near being a show truck, or if I had money I could carelessly throw at it, I would. Wait.... I've been apparently throwing money in parts at this thing for the last 1-1/2 years, so why not an aluminum radiator? With a bung. ...!

Oh yeah, that wiring diagram is wrong. Those bypass switches should only be supplying a ground to T1 and/or T2. And an LED lighted rocker switch would work, but the polarity of the LED would need to be reversed (if possible), the line and load terminals of the switch would be -12 volts, and +12 volts would then go to the terminal that previously supplied -12 volts for the LED.

 

[PetroleumJunkie412]

Have triple e-fans on mine.

Used aluminum strips for the puller fan.

Mercedes pushers are a direct bolt in.

Just be sure to out your thermostat in the lower hose. Otherwise it will never cycle. It will just stay on if in the upper.