Viscous Fan?

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tcm9669

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Hi,
Reading online I was led to believe that newer 4x4have a viscous fan, meaning that if something hits them it'll stop spinning... hence whilst doing water crossings due to the water resistance they should stop spinning and not suck in water... hence preventing the need of a tarp when doing water crossings.

I am wondering if the 2006 d22 zd30 has got this type of fan? I searched forum and online.. but could not find any information.

Thanks
 
hence preventing the need of a tarp when doing water crossings

Don't have the answer to your question, although have a wading blanket will save anything hitting your radiator and i guess also help with the bowwave also pushing water away from your truck
 
Pretty sure they are all viscous, but i wouldnt go poking a stick in there, and as noted above, they will still try and suck themselves into the radiator and wreck everything in deep water.

I think its more of a temperature thing where they kinda free-wheel until warm.

Dont quote me on all that though - I may have made all that up.
 
It's easy to tell if you have a viscous fan coupling or not. When the car's cold, engine off, pop the bonnet and try turning the fan by hand. If the fan can move without turning the shaft it's mounted on (the thick shaft that goes into the water pump) then it's a viscous hub. Most modern cars have either a viscous hub or electric fans. Hardly ever see solid fans any more.

There's a couple of reasons. Firstly, power. Driving the fan hard uses it - if the car's not up to temp, there's no sense wasting power on cooling the engine down when it doesn't need it.

Second, heat. The engine needs some heat to operate normally, usually coolant temps in a diesel are at least 85C and usually somewhere in the 90s. In order to let the car get warmer faster, don't drive the fan as hard = less cooling effect = faster warmup.

Third, noise. Above 94C my engine is really very noisy. Down a modest hill though, mild engine braking maintaining speed, you can actually hear my fluid couple disengage as the coolant hits 91C. The engine goes quiet! No more big rush of air.

It doesn't have anything to do with wading. When wading, use a wading bra. Two primary reasons: first, to stop debris from entering your grille and puncturing your radiator. Second, if the water isn't coming in through the grille, it will form a bow wave out the front leaving a nice air pocket in the engine bay keeping most of it dry. That's how you want it.

The problem with water hitting the fan - fluid couple or not - is that water is much denser than air (about 680 times denser), so the tips of the fan blades will have so much more to grip on and be able to tractor themselves further forward - and that's your radiator being chewed on right there.

The trick to avoiding that is to always use a wading bra and always enter the water with low-to-moderate revs in 4LO and keep the vehicle moving. Of course, you can only do this if you've planned your path already (or can see it).
 
Hi,
Reading online I was led to believe that newer 4x4have a viscous fan, meaning that if something hits them it'll stop spinning... hence whilst doing water crossings due to the water resistance they should stop spinning and not suck in water... hence preventing the need of a tarp when doing water crossings.

I am wondering if the 2006 d22 zd30 has got this type of fan? I searched forum and online.. but could not find any information.

Thanks
It will still spin even when it's not engaged, not enough to flex and damage the radiator if it cops a gutfull of water.
 
Excellent. Thanks guys!

Thanks Tony for the detail in your explanation.

Bottom line is, tarp can't do any harm and better to be safe than sorry.
 
This is a pretty dumb question cause it's common sense that it's going to be viscous since they haven't been direct drive belt driven for several plus decades.


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This is a pretty dumb question cause it's common sense that it's going to be viscous since they haven't been direct drive belt driven for several plus decades.


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That makes it a fantastic question, in my books. Not everyone knows. Not everyone's game enough to ask for fear of appearing stupid. TCM would not have been alone - for every person that asks a question, there are dozens of people out there (probably many more than that) who are looking for the answer to that question.

Here's something along those lines: there was a time recently where some young adults in Melbourne were learning to drive or had gotten their P's and had NEVER seen rain. Didn't know what a wet road was, or what it would do to the car.

On the surface, the members of this forum answer questions to people that ask the questions. What we don't (won't, ever) see is underneath, where search engines provide results for questions that people have, they type stuff into Google/Duckduckgo/Ecosia etc and get results that point to these pages.

A great many of those people never sign up to the forum. At any one time (example: right now) we'll have over 100 "users" connected to the forum. At the moment, that's 3 people with accounts (myself included), several dozen people here as a result of search engines, and the rest are search engines.

So what we see here only scratches the surface. There are many, many other people out there reading what we're saying and taking notice, and we'll never know. And many of them learn from their experience.

On occasion you'll get someone jump on the forum and say "long time reader, first time poster". I'll get the occasional PM from someone who got enough help from the forum to help them out considerably (eg catching a timing chain failure before it blows the motor, or cleaning the SCV for $25 vs replacing the fuel pump for $4K).

While the question on the surface looks odd, or ill-informed, it really is a good question because LOTS of people don't actually know - or didn't, because now they do!
 
This is a pretty dumb question cause it's common sense that it's going to be viscous since they haven't been direct drive belt driven for several plus decades.


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I'm sorry that not everyone is as smart as you are - clearly.

My Navara is a project car, I'm not a mechanic and I only know stuff from the research I do. Others out there go out and break their trucks because they don't research and don't ask. I'm not one of those people. Also if you read the FIRST FEW WORDS of my OP, you will see that I said that I believe newer ones have viscous... but wanted to confirm with the experts on this FORUM. This is not a mechanics garage where I'm supposed to know everything.. otherwise what's the point of me joining.

I know stuff that you definitely don't know and vice versa. So knock down your ego a notch, have a cup of tea and calm down.
 
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I'm sorry that not everyone is as smart as you are - clearly.

My Navara is a project car, I'm not a mechanic and I only know stuff from the research I do. Others out there go out and break their trucks because they don't research and don't ask. I'm not one of those people.

I know stuff that you definitely don't know and vice versa. So knock down your ego a notch, have a cup of tea and calm down.



I'm not having a go at you as much as I could mate but if it's belt driven (belt needed to make it work) then it's obviously viscous since the only other way it would work is by direct crankshaft drive like they were many decades ago. Old saying is, don't believe everything that you read on the Internet. And apply a bit of common sense. No belt means it crank driven, if it is belt driven, it's viscous which ALL engines are viscous these days and have been for many decades as I've said previously.


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It's true that people could have done numerous Google searches to find out when viscous hubs (fluid couples, viscous clutches, fan clutches, fluid clutches, fluid drives - the list of names for this one device is curious and lengthy). Unfortunately Wikipedia doesn't give a lot of detail about the "fan clutch" which is a shame.

I remember working on engines that had belt-driven water pumps with fixed fans (no fluid couple). One was an old Bedford Transit van that may not have been too original after it came back from the farm, but nevertheless it didn't know how to stop. When those changed to fluid drives I've no idea.

Actually come to think of it I was recently helping someone get a 1950s tractor going again and it had a belt-driven fan ... no fluid drive. But then it revved out at about 1200rpm and couldn't exactly do highway speeds!
 
A car bra is the go, makes sense. Will help push the water and keep a bow wave as well.

Though I have been through some pretty deep crossings in the D22 without one and the fan hasn't been a problem.

Not a bad idea to undo and WD40 your electrical plug connections first also if it's deep. Recently had an engine light come on after a crossing and engine was very rough on shut down, which was a bit of a worry. Ended up being dirty water in a plug on the side of the inlet manifold (goes to the injector pump). Quick spray of WD40 and all good again.
 
ps. Not a bad idea to put a few extra screws in the number plate either if you intend doing river crossings. The backwash has a habit of ripping them off the front of your car.
 
D40 V6 creek crossings.
An interesting thread - a couple of comments.
Alternator:
The alternator on the V6 is mounted at the lowest point on the engine. Clean water at creek crossings should be OK but could be an issue when you have to travel through kilometres of road covered with muddy water from unseasonal rain - such as The Canning recently. Apart from carrying a spare I don't see how you can prepare for an alternator failure. I did hear that one guy just hosed his out with clean water and it worked again? Perhaps mud on the brushes, but if the alternator bearings fail and that belt won't work then you are in trouble.
Breathers:
With the breathers (diffs, gearbox, transfer) I guess you terminate them high in the engine bay and hope that the wading bra does its job, or do people take them into the cabin? I recall that from the factory, some are OK and others needs work.
Firewall panel:
My Navara has no provision to pass cables from the engine bay to the cabin. I managed to cut through a large grommet insert my cables but it is nearly impossible to seal again due to poor access. Hopefully it will never be sitting in water.
Crocs:
We all hear about the idiot that charges through a crossing without checking its depth first. If it's an established well used crossing - fair enough but there are still gotchas like sometimes you need to follow an exact path.
A couple of months ago a guy in NT was killed by a croc as they walked across the crossing. All coastal rivers in Northern Australia have salties.
 
It's true that people could have done numerous Google searches to find out when viscous hubs (fluid couples, viscous clutches, fan clutches, fluid clutches, fluid drives - the list of names for this one device is curious and lengthy). Unfortunately Wikipedia doesn't give a lot of detail about the "fan clutch" which is a shame.

I remember working on engines that had belt-driven water pumps with fixed fans (no fluid couple). One was an old Bedford Transit van that may not have been too original after it came back from the farm, but nevertheless it didn't know how to stop. When those changed to fluid drives I've no idea.

Actually come to think of it I was recently helping someone get a 1950s tractor going again and it had a belt-driven fan ... no fluid drive. But then it revved out at about 1200rpm and couldn't exactly do highway speeds!

Being a bit older Tony I owned a couple of cars with belt driven solid fans,really had had to be careful putting the timing light on them,natural enemy of the timing lights.Or hands
 

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