Water Crossing with a Mechanical Fan?

dra2120

Active member
I'm sure this has been discussed before, but I couldn't find anything when I searched. For those of you who do more substantial water crossings...What do you do about mechanical engine fans? Do you switch over to a manually controlled electric fan setup, do you disconnect the drive belt before water crossings, or do you just send it and hope for the best? I highly doubt I will ever be in a situation where I would be going through that much water, but I'm curious what people who do go through that much water end up having to do.
 

SRN

Adventurer
What is your definition of "substantial"? I've been through many water crossings up to the grill (and a few higher!) and as long as you keep moving with a bow wake, you shouldn't have a problem if it's for a minute or two. Its when you stop in the water when you can start to have issues. I'm less worried about the fan and drive assembly than I am about the air intake and diff/tranny/t-case breathers. A lot can go wrong if you suck water into any of those!
 

dra2120

Active member
I'm thinking like water up to the headlights or more...I did a couple quick water crossings in Alaska with my LandCruiser that were up over the hood, but they were just quick in and out, 5-10 seconds at most, but for people who are doing that more often or for longer periods of time I'm wondering what they do.
 

85_Ranger4x4

Well-known member
Electric fan might sound good but the motor won't like silt and whatnot.

The global guys I watch on tv have belt driven fans.
 

roving1

Well-known member
The viscous clutch cools down and lets the fan slip pretty quick so as long as you are not entering water crossings pinging off the limiter it usually isn't an issue. If you are paranoid about it dump a few buckets of water on the rad and fan hub before a deep crossing.
 

alanymarce

Well-known member
Never really worried about it. I agree that if you don't have a viscous coupling the belt will slip and you'll have no problem. Lots of times crossings of up to 30s or so with no trouble.
 

slomatt

Adventurer
A friend of mine has broken multiple blades of his electric fan (several different times) during water crossings, while the rest of the group's mechanical fans have had no issues. He eventually re-installed the manual fan and has not had a problem since then. This isn't to say that mechanical fans won't ever break in deep water, just that in my experience the electric fans seem more prone to damage.
 

Peter_n_Margaret

Adventurer
Water deep enough to go through the grille deserves a "nappy".
Water likely to significantly contact the fan can draw the fan into contact with the radiator and that is a bad scene. Remove the fan.
F350 4WD. Nappy in place.
Mitchell Plateau 09.jpg
Cheers,
Peter
OKA196 motorhome
 

lugueto

Adventurer
I do multiple deep water crossings per trip. Anywhere from covering the bumper to (usually) completely dunking the hood. Mind you, my trips are in really warm weather, crossing a stream mid-day would mean temps are on the high 30s Celsius and our fan(s) will be spinning.

Here's my take from experience:

If you drive a really old vehicle with a fixed metal fan, its better to be careful. Your fan blade can flex and open a hole in your radiator. I've seen them do it before the belt slips, all it takes is a little contact for the radiator to open. Low RPMs are your friend. A well-placed tarp can help briefly. If the risk is too high, better to remove the fan, which is usually easy.

If you drive a really modern vehicle with electric fans with no bypass, and drive on hot climates, the plastic fans will bend and break as soon as they hit the water. You absolutely need to add a manual off switch for them.

If you drive a vehicle with a belt-driven fan with a fan clutch, then the risk is completely mitigated. Replacing these for electrical fans is, IMO, not worth it because there is simply no risk of damaging the fan or radiator.
 
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1stDeuce

Explorer
The last two posts above contain what I would call traditional wisdom concerning non-clutched fans. They detail the best way to "play it safe" if you're really worried.
That said, vehicles with factory non-clutched metal fans ceased production in about 1980, if not before. (My '78 Chevy K10 with a 250 straight six had no clutch and a 4 blade fan.)
The reality is that if you're going carefully, he first bit of water that the fan throws wets the v-belt and even a properly torqued v-belt will immediately slip when you soak it. Those fans are HEAVY, and I've never seen one bend, even when dropped into the water at high rev's. I ran through hood deep water a few times with that old K10 with no ill effects. (to the fan or radiator at least...)

I don't see how anyone doing anything could bend the old 4 or 6 blade factory metal fans, as it's impossible to flex them more than about 1/4" by hand. I would be leery of a dunking an aftermarket "flex" fan with the aluminum blades that are supposed to flex to reduce flow at high RPM's, but I'm sure many of those too have been dunked with no ill effects...

You are likely driving a vehicle that has a fan clutch, and if so, I would side with Laguento and say that it's a complete non-issue unless perhaps you're driving like a complete idiot. My TJ has been bumper to headlight deep in crossings multiple times. When you first get to deeper water, the fan splashes for half a second, then nothing. No bent fan, no slipping serp belt, the fan clutch just slips and you're good. I've never seen a bent fan or damaged radiator from responsibly driven water crossings.

To this point, if you watch a few FWD 24-7 vids on youtube, you'll notice that they never do anything about fans during crossings. I would assume most of those vehicles have belt driven fans. Water over the hood at times, and I've never seen them disconnect a fan, nor have I seen them cause damage, and they run water crossings pretty hot, likely for "exciting" video footage, and the temp is pretty high for a lot of those vids...

As for electric fans, we submerged the fan while it was running 10 times or so when I worked for Jeep (2.4L TJ Wrangler has an electric fan) and it never broke or died. I doubt it would have had a long life with the clay water we subjected it to, but I don't even recall it blowing the fuse, and we drove that TJ for more than a year after with that fan and w/o issue or fan failure.
 
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