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Driving through water

Discussion in 'Motoring Related Discussion' started by d215yq, Oct 19, 2018.

  1. d215yq

    d215yq Senior Member

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    Having quite a week, lost wallet, at weekend caught on a major A road in a storm where one could see a microsecond after each wiper had passed and then nothing which was "interesting".

    Then yesterday everyone left office as there were flood warnings but as I only go in the office twice a week I thought I'd stay. Motorway was closed due to flooding so took some rural back routes which I quickly realised was a bit risky. Ended up going through sections that seemed like up to the bottom of the bumper and needed first gear to actually drag the car through the resistance (not sure if actually up to the bumper as didn't get out to look!).

    Then after that section 3-4 inches standing water for another 10 miles taken very slowly. Not a pleasant experience but made it back. Made me wonder what exactly are cars designed for/what can they take. I suppose the W124 has no electrics and air intake is at top of grill but presumably it can't just carry on up to that point regardless or it would not have enough power/traction to pull through the water or would even float and also would damage alternator/belts, etc
     
  2. Blobcat

    Blobcat Moderator

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    Depends where the air intake is as that is usually the limiting factor (it's what caused early X5's to drown out - having the air intake low down)

    You'd have to be pretty deep to float - one of the benefits of my Land Rover is that it lets so much water in it won't float even when it's level with the top of the bonnet :D
     
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  3. John Laidlaw

    John Laidlaw Senior Member

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    Biggest issue as I understand apart from above would be water being inadvertently sucked up the exhaust which would ruin your day for sure!
     
  4. daveenty

    daveenty Senior Member

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    The rain in Spain. :)

    I love the way that when it does rain heavily that all your white road markings disappear, makes it more of a challenge I suppose. This was when I was working in Andalusia which was a few years ago, so I suppose it could have changed now.
     
  5. towat

    towat Senior Member

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    Just get a landcruiser.

     
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  6. flowrider99

    flowrider99 Senior Member

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    Doesn't the exhaust only blow out so as long as the engine is running there wont be an issue.
     
  7. flowrider99

    flowrider99 Senior Member

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    Many years ago i blew a 2.0 petrol engine in a Ford Sierra by going through a large, deepish puddle. The air intake was behind the front bumper (i didn't know it at the time) and i managed to suck up water and push two pistons out the side of the block.
     
    Last edited: Oct 19, 2018
  8. John Laidlaw

    John Laidlaw Senior Member

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    Normally yes as the exhaust gases themselves will fill the void, but imagine what happens when you rev hard then come off the throttle ? Unlikely you’d do it whilst trying to power through despite water but....
    As said it’s the air intakes which are a much bigger issue (that and frying all your electrics!) :D
     
  9. Blobcat

    Blobcat Moderator

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    Never been an issue in my Land Rover and the exhaust spends most of it's time underwater when I've been playing
     
  10. OP
    d215yq

    d215yq Senior Member

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    To be fair annual rainfall in Valencia (and most of the mediterranean coast) is about 50% higher than london and we typically have about 20 days a year of rain so you know about it when it comes!...and yes it does make the markings and everything dissappear but to be fair, whenever I've driven in heavy rain here, everyone has hazard lights on (easier to see you/judge distance) and slows to 30mph and I don't see crashes. Compare to the Uk where for a substantial minority it is ease off to 60 back off to allow the correct gap for dry weather and put the fog lights on...
     
  11. umblecumbuz

    umblecumbuz Senior Member

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    A seldom anticipated issue with many cars nowdays is water getting to the cps. (Peugeot had a period where the cps was fitted at the lowest point of the bell housing - useless in a few inches of flood water). This will effectively stop the engine, even in shallow water if you get it wrong, and needs drying out before the engine will restart. Fortunately, splashing onto the electronics in Mercs and many other makes is minimised because cars now fit plastic undertrays. These do not stop water getting into the works if you venture too deep - they just stop splashing.

    It goes without saying that driving slowly is common sense - witness the idiots who race through floods, only to stutter to a halt half a mile down the road.
     
  12. EmilysDad

    EmilysDad Senior Member

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  13. LostKiwi

    LostKiwi Senior Member

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    That's actually a myth and only an issue if the engine stalls. Under running conditions there is enough pressure in the exhaust to prevent water ingress.
    My Defender regularly waded through near bonnet depth water with a standard exhaust and never had a problem.

    The factors that come into play in deep water are:
    Electronics and sensors (and their connections)
    Air intake height/location.
    Gearbox and differential breather locations
    Wheel bearings.

    And in extreme situations driver air intake!
     
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  14. rorywquin

    rorywquin Senior Member

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    And I believe that if you did stall, the water is unlikely to push back up to outlet valve level with the possible airlocks in the pipes as well.....I think catalytic converters are potentially the biggest victims.

    Like LK been through deepish water in a variety of off road vehicles and never had a problem. Have seen damage to radiators with fan blades flexing into them because of water.

    Our rule of thumb was that if the water was above knee deep and we could not easily walk through then find another route and cross deep water as last resort. Always amazes me seeing people driving into water and they have no idea how deep it is of the strength of the current.
     
  15. EmilysDad

    EmilysDad Senior Member

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    I once had a bow wave over the bonnet of my Roadster when crossing a ford ..... the Roadster in front got through OK so I followed! :D
     
  16. LostKiwi

    LostKiwi Senior Member

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    A tragic example of that was the accident on Strata Florida in Wales some years ago where a girl drowned when their vehicle was pushed over by the water.

    For those who don't know about Strata Florida it's a route (track) through the Welsh hills that follows the line of a river, crossing it around a dozen times... After rain it can be lethal.
     
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  17. LostKiwi

    LostKiwi Senior Member

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  18. Rappey69

    Rappey69 Senior Member

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    The strata florida accident was a landrover which got swept away, driven by a pcso with two young girls in .
    He got two years in prison for careless driving and a 3 year ban.
    The vast majority of off roaders have no concept of the power of flowing water...
    Being a yachtsman I understand it and many times have warned bikes, quads and cars about not crossing a particular river due to the current, which they failed to grasp.
    The killer for road cars fording flood water is not always the depth, but the speed they use , creating a bow wave which can double the perceived depth, flooding the engine.. Or worse still the bow wave the oncoming idiot causes by charging through the water, swamping your engine.
    Never drive through flood water until you have seen someone else go first to see how deep it is !!!
     
  19. EmilysDad

    EmilysDad Senior Member

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    Like these idiots? :rolleyes:
     
  20. 3146bj

    3146bj Senior Member

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    [QUOTE="
    Never drive through flood water until you have seen someone else go first to see how deep it is !!![/QUOTE]

    Not always somebody to watch go first, so an option is to walk through it before you drive it (not recommended if there are crocodiles in the river, like we get in North Queensland or the Northern Territory).

    There are a number of tricks for experienced drivers to use, such as drive just fast enough to establish a bow wave, but not fast enough to overtake it so it swamps the engine, that make it possible to get through quite deep water, but always be aware that most cars will float in fairly shallow water.

    A tip I got from an old guy in the country for when the car is washed off a ford - "stay in the car with windows up until it stops moving as it is pretty solid protection for the passengers and there is quite a lot of air trapped inside. To get out smash a window on the side, that will let you get out without letting all the air escape". Sounds quite logical, and I believe he had done it a couple of times, but in a panic situation, logic doesn't always prevail!
     

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