Water crossings

Submitted: Saturday, Jul 19, 2003 at 08:45
ThreadID: 6050 Views:1663 Replies:6 FollowUps:8
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can anyone tell me why you shouldnt change gear while doing a water crossing?
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Reply By: member-skippyking - Saturday, Jul 19, 2003 at 08:52

Saturday, Jul 19, 2003 at 08:52
I'm not overly experienced at river crossings but I imagine it has to do with the forward momentum keeping most of the water out of the engine bay and the risk you run with stalling.
SKMost human problems can be solved by an appropriate charge of high
explosive."
AnswerID: 25340

Follow Up By: Rod Mcleod - Saturday, Jul 19, 2003 at 09:18

Saturday, Jul 19, 2003 at 09:18
Changing gears mid stream allows water to get between the clutch face & the pressure plate thus letting the clutch slip, changing more than once in deep water can cause the vehicle to come to a complete stop, consider the amount of weight the vehicle is pushing from the water & the truck just slows while the motor is thrashing in ever increasing deep water.
Rod Mcleod
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Reply By: Member - Chris - Saturday, Jul 19, 2003 at 10:34

Saturday, Jul 19, 2003 at 10:34
In addition to Rod's answer, the 'bow wave' built up while proceeding slowly could collapse into your engine bay when your truck slows during the gear change process. Chris
<- 1996 Troopy, the best!
AnswerID: 25341

Reply By: Jack - Saturday, Jul 19, 2003 at 13:27

Saturday, Jul 19, 2003 at 13:27
Hi Jonny:

All the above are correct ... loss of momentum can cause the water to surge into your engine bay. The other point is for beach driving (eg Fraser Island), where if you stop there, with the water swirling around, you sink .. and fairly rapidly at that.

As someone once told me ... "just keep moving .. it doesn't matter in which direction ... as long as you are moving" ....
Cheers
Jack
AnswerID: 25347

Follow Up By: Member - Bonz (Vic) - Saturday, Jul 19, 2003 at 14:46

Saturday, Jul 19, 2003 at 14:46
It DOES matter which direction..... DOWNSTREAM is BAD!!!

Have a fraser daySo many places to go!
So much work to do :0(
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Reply By: Jack - Saturday, Jul 19, 2003 at 16:25

Saturday, Jul 19, 2003 at 16:25
Hi Bonz:

Point taken! Out to sea is just as bad, I think.

Jack
AnswerID: 25353

Follow Up By: Member - AndrewPatrol - Saturday, Jul 19, 2003 at 17:54

Saturday, Jul 19, 2003 at 17:54
Unless you gotta Toyota Surf !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Reply By: Waynepd (NSW) - Saturday, Jul 19, 2003 at 19:50

Saturday, Jul 19, 2003 at 19:50
As far as I know the clutch is the main problem. Water and mud between the plates will cause slipping and you will slow down or even stop depending on how well your clutch was in the first place.

I hadn't thought about the bow wave thing but that makes sense too. That can cause the fan to be drawn into the radiator core as it acts like a propeller and flexes forward.

So you pick a gear and stick to it.

another question arising from this
So what happens if you pick the wrong gear and stall in midstream, do you leave it in gear and wait to be winched out?? chances are the the starter would be underwater.. ouch not a nice thought eh?Cheers
waynepd
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AnswerID: 25367

Follow Up By: Mick - Saturday, Jul 19, 2003 at 23:07

Saturday, Jul 19, 2003 at 23:07
Oh boy, Wayne and Johnnyknowaverylittle, I think you are both well and truly in need of instruction! Enrol in a 4wd course on Monday!!! Wayne, if you find you have chosen the wrong gear for a crossing, don't let it stall (I don't imagine you would be so far out in your choice that momentum couldn't be maintained) If it did stall, do a stall start and DON'T TOUCH THE CLUTCH. Select low low and restart the motor.
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Follow Up By: Waynepd (NSW) - Saturday, Jul 19, 2003 at 23:53

Saturday, Jul 19, 2003 at 23:53
Hi Mick,
point 1) if you read my reply, you would have noticed that I was talking about the starter being underwater, which could quite easily be the case. I don't think a starter that is shorted out by immersion is going to be of much use.
Otherwise your method is the correct one to use.
point 2) if i was in 4h 2nd gear, stalled becuase of a rock or hole that i missed on my walkthru and needed to go into 4L to start the car in gear, I Have to use the clutch to move the tranfer case into 4L.

In my GU I can move from 2wd to 4H on the fly no clutch but i have to be stationary and use the clutch to change from 4H to 4LCheers
waynepd
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Follow Up By: Mick - Sunday, Jul 20, 2003 at 10:10

Sunday, Jul 20, 2003 at 10:10
Wayne, if you stall your vehicle, you will be both stationary and your engine will have stopped Go out to your car, make sure that the engine is not running (same as it would be if you had stalled) and you'll find the transmission can be shifted without touching the clutch!!!!!!!!! And never try a water crossing in 4H2nd gear either. mmmmm think about enrolling in that 4wd course!
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Follow Up By: stillthinkinaboutit - Sunday, Jul 20, 2003 at 20:30

Sunday, Jul 20, 2003 at 20:30
The starter motor will still work underwater, water is not that good a conductor of electricity and for low voltage DC systems such as automotive electrics it has neglible effect. Different if you wet the high voltage stuff like the coil, distributor, plugs, leads ECU etc, then it is stuck.
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Reply By: jonny knowalittlebit - Sunday, Jul 20, 2003 at 14:25

Sunday, Jul 20, 2003 at 14:25
thanks for all the replys positive and the one having a dig at me and wayne. some people hey.... if you dont ask you might never know the question was why not something that happened its just something that is so well enfasized but never explained.
AnswerID: 25400

Follow Up By: Mick - Sunday, Jul 20, 2003 at 22:44

Sunday, Jul 20, 2003 at 22:44
Sorry if I hurt your feelings Jonny but I seriously do mean that you should do a 4wd course. There's a heap of things both major and minor that can cause ill prepared, ill equipped or uninformed drivers to get into all sorts of strife in the bush. A course will assist you greatly and as well as instructing you will have your questions answered. Remember too that if you have problems when off road they often affect others - fellow travellers who have to help you and even rescue services that have to come and save you. Good luck!!
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