Radiator Fan Override Switch (The Easy Way)

[mtkorn1972]

Amazing write up on the over ride switch. This is what I plan to do when I get enough guys to start cutting wires, lol.
Wondering if anyone has done the other option you listed having normal operation, full on, and full off for water crossings, and how it worked out for them. I have read thru most of the replies to your write up and didn't seem to find anything saying that they had done the 2nd option and that it worked, or they had issues, etc.
If anyone has wired theirs up that way, please let me know how it worked out for you. I just don't want to be the Guinea pig

[mtkorn1972]

Forgot to mention that mine is a 2000 XJ Limited

[lazyxj]

Originally Posted by mtkorn1972

Wondering if anyone has done the other option you listed having normal operation, full on, and full off for water crossings, and how it worked out for them. I have read thru most of the replies to your write up and didn't seem to find anything saying that they had done the 2nd option and that it worked, or they had issues, etc.

Even if the electric fan's power is shut off, the engine-driven fan will continue churning.
If you are going to get into water that deep, a raised intake will be needed to prevent sucking water into the airbox and hydro locking the engine.
You could use a plastic sheet to cover the radiator grill, I have used cardboard in a pinch, to limit water intake.
In addition to an over-ride switch, I added a three-minute timer, with a separate activation button, to run the fan when shutting a hot engine down, to combat summertime vapor locking.
https://www.flickr.com/photos/lwade/...7617434915718/

[mtkorn1972]

Not concerned with the hydro locking issue since I do have a safari snorkel and custom airbox set up. I've got that covered. I have heard that it is bad of the electric fan comes on while in deep water and can cause it to totally fail. That's my concern. I like the XJ's setup with both mechanical and electrical fans. I have functioning hood vents, bored out water neck, 3 core copper radiator and since regearing to 4.88s with 35s I can crawl in 90 degree weather and it only hits about 215-220 tops.
Since I have custom hydroboost brakes I want to make sure the power steering pump and fluid stays cool. I am running a trans cooler for the power steering but it is on the half of radiator covered by electric fan. Since that only comes on when around 217 and for a short time, it does no good for keeping the power steering cool. I have already smoked a new PSC pump due to fluid getting hot during crawling.
With a s cool as my has been running, I prob don't need the full off mode. Kinda torn on the idea. I do like the idea of the timer that you installed for heat soak issues though. I had an issue with that when I bought it. It was so bad it melted all the wires going along the top of the engine into one solid mass. I have since cut all the wires at various spots on the firewall, replaced with color matching wires, new terminals and connectors (crimped and soldered) and extra heat protection loom.
By chance you have a write up on the timer deal or a link?

[kastein]

Basically every upper engine harness I've ever seen on an XJ, any year, has been fused into a solid block like that - not just 00+. It's never really presented an issue unless you have to work on it, then it gets a bit crunchy.

[mtkorn1972]

Kastein, I came across this way of hooking up switch and wondered of there is any issue with doing it this way:
https://www.cherokeetalk.com/threads...e-delay.69801/
I hooked everything up yesterday as a small test. If I used an on/off toggle it would stay on as long as I wanted, but wondering if there would be any I'll affects from doing it this way.
Your thoughts?

[lazyxj]

The timer I used is activated by pushing a monentary-on button once, to set it for three minutes. It is powered when the ignition is either on or off

For constant operation, when the engine is running, another button (push on, push off) controls the added fan relay and powers a dash light, showing the fan is operating.

[IslanderOffRoad]

Originally Posted by mtkorn1972

Kastein, I came across this way of hooking up switch and wondered of there is any issue with doing it this way:
https://www.cherokeetalk.com/threads...e-delay.69801/
I hooked everything up yesterday as a small test. If I used an on/off toggle it would stay on as long as I wanted, but wondering if there would be any I'll affects from doing it this way.
Your thoughts?

I attempted to do it that way. The relay he used is no longer available, and the “new” version of it didn’t work for me when I attempted it.

My goal was full manual control and a shutdown timer for heat soak. Here’s how I went about it:

https://www.naxja.org/forum/showthre...#post246673926

[mtkorn1972]

I got the new bueller time delay relay and had the same issue of it not working. I got in touch with the seller to find out what was going on. The new version is wired differently from a standard relay, which kinda kills my idea of being able to swap in any relay in case the time delay unit failed. Here's the email response I got from them in regards to the wiring:

These are wired differently than a standard relay:

Pin configuration:
Pin 30 - Must have constant or accessory 12 volts all-time, as this is what powers the circuit on the relay
Pin 85 - Ground
Pin 86 - Single pulse (+12 volts) to trigger time delay off (Constant 12 volts can be applied and once +12 volts is removed relay will stay latched for duration of timer.)
Pin 87a - +12 volt output (Normally closed contact - on except when time delay is active)
Pin 87 - +12 volt output (Normally open contact - on for duration of set time)

These relays don't come with instruction telling you to wire them differently. Not sure what I want to do yet.