Have Moses ride shotgun.

 

All the precautions stated above and for fun add a snorkel. IMO they look awsome.

 

• Not sure why restarting a stalled engine would damage it. Other than that, agree with the above advice. I would suggest if you're concerned about stalling it and have a manual, cross in 4WD low so you can restart the engine without pressing the clutch (did you know you can do that?). Make sure you select the gear you want for the whole run so you won't shift. And if you prefer to not restart if you stall, consider mounting your tow strap/hooking up your winch controller and reeling out some line in advance so you can minimize your water contact (just throw it in the Jeep with you).
• If you plan to do much fording, definitely consider a snorkel (then you get to go first, LOL).
• Bigger tires give deeper performance, as does a lift, but not if you don't extend the breather lines.
• Extend the breather lines, especially if you extend them to the air box, which is connected to a snorkel. If you have a manual tranny, there is a breather nipple, but no line to it. So, it's your low point.
• Let the diff's cool before crossing if you aren't confident that the breathers and manual tranny nipple will be above the water level--a hot diffy when it gets hit by cold water will cause the diffy to suck in something. That's what the breathers are for: To keep it from sucking that water past the seals. It needs to be sucking air.
• You turn off the fan to keep it from throwing water all over and maybe wreaking havoc with the underhood electronics. I like having a switch.
• Go slow. No wake is the best advice.
• Low water crossings can become slick from the algae that grows on it. Remember that if the water is flowing quickly across it.
• After you return home, check all of your fluids for water contamination. Change if there is any.

Have fun out there, but stay on legal crossings. It's one of my favorite activities--here's an awesome one we did a few weeks ago right at the beginning of this video ...

http://www.youtube.com/watch?v=aLkNU8d8w-c Oh, and my fan off switch ...

 

^^ Great video. Do you have a write-up, or can you point me to any instructions on how you installed/wired your fan switch to your sPod?

 

I never wrote it up (I know I should), but here are some thoughts to help you through it, as well as a diagram ...

The sPOD can't do it directly for two reasons: It's designed to turn things on, not to keep things from turning on. So, if you were to wire it through the sPOD you'd have to remember to turn your fan on and off manually (if you left it on when parked, the circuitry would be powered and drain your battery). On top of that, the sPOD is limited to 30 amps per circuit, IIRC. The 3.8L JK fan has a 50 amp fuse, so I figure the fan draws between 40-45 amps. So, you don't want that much current going through one circuit on your sPOD.

This dictates that you need a separate relay that the sPOD will control. But, don't forget that 40-45 amp requirement. On top of that, there's a lot of really cheap, Chinese junk out there in the form of relays. I checked out a couple and they weighed nothing. Well, it takes metal to carry current, and I have a problem trusting heavy current carrying to something that may be suspect. So I opted for an 80 amp relay, and a pretty stout one at that. On top of that, many of the relays out there are four pin and not five. That is, just like the sPOD, they are designed to turn things on, not keep them on. The fifth pin provides the path for current when the relay is deactivated, so you must have it. And, by designing it this way the most common failure modes (loss of power through the sPOD, stuck relay, etc) leave the engine fan operation at normal. It would be very unusual for the relay to get stuck activated, thus turning off the engine fan (writes the guy whose sPOD failed while on the run in the video above causing the engine to overheat--but that was a bad switch in the sPOD controller and easily corrected by turning off the sPOD lighting circuit. Contacted sPOD and they had me send them the bad switch because they never saw one fail like that before). Ultimately, this is the relay I went with ...

Fan Relay

Now, do be aware that this relay will not fit a normal horn/fan relay socket because some of the terminals on it are too large. It does come with the necessary over-sized spade lugs to make the connection. So, I used those lugs and a couple smaller ones (for the coil current) to connect the relay up. That does mean that it isn't just plug to replace, if ever needed. You'll have to pull off the four (you don't need one) spade lugs and manually reconnect each one to the new relay.

Finally, after getting it all wired up I wrapped the relay with F-4 tape (F4 Tape - Self-Fusing Silicone Tape - History of F-4 Tape) and used a zip tie to secure the bundle to the fan shroud.

Here's the wiring diagram you'll need ...
EDIT: I drew this from memory at 0'dark-thirty this morning and got the color of one wire wrong. This diagram is corrected (white should be blue).


Do be aware that this is for the 3.8L engine. A friend of mine wired one up to his 3.6L motor using my design, but there are three wires to the engine fan. He cut the existing black wire, as did I, and said he thinks it's working okay. He was uncertain if the fan was sometimes going into a low speed mode when the switch should have had the fan off. Since he lives in WA and I'm in OK, I haven't had a chance to check out his rig. But, I will in the very near future when we get together for a run, so I hope to be a little smarter on the Pentastars after. If anyone does this and has a Pentastar, would appreciate you letting me know (especially by PM since I don't catch every post on the forum) what you've learned.

 

Excellent drawing and description Mark. As an electronics engineer I cringe at some people's DIY projects. Its also crazy to see some of these aftermarket designs and how cheap some stuff is made.

 

So for us DYI's who know just enough to be dangerous, a 60+ amp normally closed relay is the ticket? Would a four pole switch work? How's the fifth utilized? I don't see the 87 terminal used in your schematic. Thanks

 

You want the fan to be connected to the normally closed side and 87 is just acting as an open circuit cutting power to the fan.

Sent from my ADR6425LVW using Tapatalk

 

Thanks for the diagram and tips. I go through a lot of swampy muddy water crossings, and after seeing what gets slung around the engine compartment afterwards, this is a project I need to get done.

I stumbled across F4 tape almost by accident and I've found a lot of uses for it around the house, good stuff.

 

I used to work on F4s. Year in Mojave Desert and nearly three in Thailand during Vietnam. Love the tape!