Reference post 25613 "Fans getting sucked in"

Submitted: Tuesday, Aug 16, 2005 at 10:38
ThreadID: 25633 Views:2858 Replies:4 FollowUps:8
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In reference to comments made in post 25613 - such as "and to reduce the risk of the Fan being sucked into the radiator, damaging or breaking both"

It's the first time I've heard of it, and I can't see which laws of physics or mechanics would explain it. In fact it sounds like a bit of an "old spouse's tale".

So - Can someone please explain how a fan can get sucked into the radiator?

Jeff
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Reply By: Andrew (Whyalla SA) - Tuesday, Aug 16, 2005 at 10:45

Tuesday, Aug 16, 2005 at 10:45
When submerged in water, instead of being a fan pushing air backwards it becomes a propeller with the tips being driven forwards, possibly making contact with the radiator.
AnswerID: 125383

Reply By: Member - Chrispy (NSW) - Tuesday, Aug 16, 2005 at 10:49

Tuesday, Aug 16, 2005 at 10:49
It all depends on the car Jeff. Some have fans that are way closer to the radiator than others. I've seen it happen on a diesel 80-series - more than once. The fan turns fast (low range 2nd gear water crossing means quite a few revs) and if you are going too slowly and water fills the cavity behind the radiator, it simply does as a boat propellor does - it pulls through the water and the plastic fan blades bend forward to hit the radiator. It does happen!

If you think that a fan is designed to PULL air in through the radiator - it's turning in the correct direction to pull FORWARD if given water to do it in.

This is why I trap my fan using a loop of wire to stop it turning temporarily against the viscous coupling.
AnswerID: 125384

Follow Up By: Hairy - Tuesday, Aug 16, 2005 at 16:10

Tuesday, Aug 16, 2005 at 16:10
Shouldnt a viscous fan stop as it digs in to the water if working prperly?
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Follow Up By: Member - Chrispy (NSW) - Tuesday, Aug 16, 2005 at 16:34

Tuesday, Aug 16, 2005 at 16:34
When new - yes. As viscous fans age, the viscous fluid (silicone of some sort) tends to thicken, and eventually they don't work. I've already replaced one on one of our Patrols. Some people manage to pull them apart and inject new fluid in - but i've heard that it isn't really practical.
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FollowupID: 380183

Follow Up By: Truckster (Vic) - Tuesday, Aug 16, 2005 at 20:57

Tuesday, Aug 16, 2005 at 20:57
Crispy

http://www.off-road.com/~estegall/tech/fanclutch/fanclutch.html

very practical... had mine done by berrima before I realised how psis easy it is
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Follow Up By: Member - Chrispy (NSW) - Tuesday, Aug 16, 2005 at 21:35

Tuesday, Aug 16, 2005 at 21:35
Hmm,... I've had a look at the Patrol ones and they're nothing like the Toyota ones. They seem impossible to split open. Oh well.. I bought a new-ish one from a wrecker for about $45.00 if I remember rightly.
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FollowupID: 380225

Follow Up By: Truckster (Vic) - Wednesday, Aug 17, 2005 at 10:11

Wednesday, Aug 17, 2005 at 10:11
They do come apart.. Rebuild your old one, keep for a spare.. not that you should need it, but always handy
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FollowupID: 380255

Follow Up By: Member - Chrispy (NSW) - Wednesday, Aug 17, 2005 at 10:17

Wednesday, Aug 17, 2005 at 10:17
Hmmm... I'll have another go on the one that came off. Actually thinking about it, it's probably made by the same third party that makes Toyota's ones. Thanks Truckster - I'll just bash it harder this time ;)
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Follow Up By: Truckster (Vic) - Wednesday, Aug 17, 2005 at 10:18

Wednesday, Aug 17, 2005 at 10:18
They can be a real female sex organ nickname to get apart.. just persist ;) Beer and hammer work too ;)~
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Reply By: Member - Jay Gee (WA) - Tuesday, Aug 16, 2005 at 10:52

Tuesday, Aug 16, 2005 at 10:52
OK - It all makes sense now.
AnswerID: 125385

Follow Up By: Footloose - Tuesday, Aug 16, 2005 at 11:04

Tuesday, Aug 16, 2005 at 11:04
Water crossing number 1. Fan destroyed radiator, a week in Weipa waiting for it to be fixed in Cairns.
Water crossing number 2, blind across front, no problems.
Thats my xperience, logic be buggered :))
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FollowupID: 380149

Reply By: peteC - Tuesday, Aug 23, 2005 at 21:57

Tuesday, Aug 23, 2005 at 21:57
Bugger, I thought the centrifical fan ripped the radiator in half when I went thru the water crossing. Then with no water in the radiator the temp guage didnt move off half way (because of no water ) and the motor seized from overheating. You have another theory? Probably not. Bet you will come up with an "old spouse's tale" when it happens to you.
AnswerID: 126536

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