fan-toggled to always on?

I have an 87' 4.0 XJ and in the heat, (I know the closed system sucks) it tends to get too hot. So last night I spliced the fan wires and ran a toggle to the power side and power from the fuse box. This now allows me to turn on the fan when the engine gets warm and leave it on the entire time. Can the fan motor take the constant power without burning up? (is the fan only intermentent?) Or should I switch it back becasue it doesn't always come on in the right temp range, but I don't won't to burn it up. I prefer this way too b/c of any water crossings. I can just turn it off so it doesn't short. Thoughts and comments?

I had this rigged up by Mil when we were at Moab a few years ago. There isn't a real problem with having the fan run all of the time. The fan in my truck, however, finally went bad and I had to replace it. About two months ago the truck started to overheat and I replaced all of the hoses, had the radiator cleaned, and replaced the overflow bottle. You wouldn't believe it, but now the truck runs at 170. It hardly ever gets past 200. This is the first time since I have had the truck, that it has ran this cool. It's an '87 Limited.

Cool, thanks! Just have to wire up a relay this afternoon

I have had mine wired through a relay to a dash-mounted toggle... no problems so far, (since 10-03 & approx 13,000 miles)

I just cut it on whenever I get into slow traffic, or when trail riding.

dandecicco, how old is the radiator in your XJ? Have you ever replaced the radiator? Have you ever changed the mechanical fan clutch?

I have a 88 XJ Pioneer, 4.0, AW4 and know what you are dealing with when it comes to cooling systems. I still run the "closed system" on my 88 XJ, I like having a reservoir of coolant above the engine so I know the cooling passages in entire head has coolant in it. I do not think an "open system" can always assure that.

If the radiator is over 7 years old or if the fan clutch is over 5 years old replace them both. Parts do wear out especially after 17 years if those items are OEM parts.

I think a new radiator, radiator hoses, pressure bottle, "radiator cap", thermostat and heater hoses will solve your problems and decrease an unplanned failure. You can get a new pressure bottle with cap for $20 from quadratech.

I personally change fan belts and hoses every 4 years, regardless of miles, on my vehicles. Learned those lessons the hard way.

If you run two wires from the switch and use the switch to jump the thermal switch (bottom left of radiator). The fan will work off of the stock relay. Just jump it after the diode pack (if you have A/C) close to the thermal switch connector.

"I think a new radiator, radiator hoses, pressure bottle, "radiator cap", thermostat and heater hoses will solve your problems and decrease an unplanned failure. You can get a new pressure bottle with cap for $20 from quadratech.

I personally change fan belts and hoses every 4 years, regardless of miles, on my vehicles. Learned those lessons the hard way."

Yup I did all that, but the rad. is pretty old and my budget has run dry so it will have to stay for a while. Temp is good though so I am not too worried. I have thought about jumping the factory relay, but I want to start replacing what I can with stuff that I install so I know how to trouble shoot. Just preference, but thanks for the advice.

Now, on the way home from work, damn thing wouldn't drop below 2200 rpms (engine) so I need to clean out the throttle body. probably is gummed up and causing it to stick b/c if I turn it off and open the throttle all the way, it drops back down to 700 rpms at idle. JOY!

i've had my stock electric fan wired to a toggle (and relay) for a year now, and I have run it for 6 hours continously before (trail). I wouldn't be too worried about burning it out, mine has been very resiliant (sp?) and they are real cheap at Pick N Pull anyway.

dandecicco said:

... (I know the closed system sucks) ...

Click to expand...

Might I ask how you "know" this? Especially because it isn't true. The closed system cools just as well as the open system. In fact, if you look around you'll find that a lot of vehicles on the road these days use variations on the "closed" system.

The closed system does NOT suck. Your radiator is dead. When I replaced the radiator on my '88 I stayed with the closed system, and once I changed the radiator and fan clutch I have had better cooling than it had when new.

I suspect you have been reading too many posts by people who don't understand how cooling systems work.

Actually,
Never said that my temp was running high so my only point about the closed system is strictly preference. I am a 4.2L CJ owner (sold to ladywolf . . . you go Kris!) and moved to the XJ for family fun and outings. After doing an entire frame up, I know the 4.2 like the back of my hand. The 4.0 closed system on the XJ is all new to me and I am learning as I go along.

For trail purposes, I would like to have something I can take apart and trouble shoot with my eyes closed and the closed system allows for more things that I would have to learn and figure out (now on the Con, this is bad, but in town no biggy). I have a small child to worry about, not an XJ while on the trail. This is why I would like to convert to something that I know more about. MY other Jeep (wife's) is a Grand Cherokee and also an open system and I would like to have all of the jeeps running on the same systems so that parts can go back and forth.

But, let me say, your replies to my newbie XJ questions have been fantastic and if I ever run into you on the trail or where ever, I owe you a beer or at least a hand shake. I am not putting down the closed system per say, just preference, Eagle.

As I am tearing into this XJ, I keep running into problems that the normal person that drives to the store and picking up kids wouldn't run into and I am trying to think ahead. That is all my friend

Dan