Driving through flooded roads

by clarkescribe Sun Oct 13, 2024 12:57 am

My question is how deep a water can we safely drive through? (given the normal practice of going slow to avoid a bow wave etc)

We have had a lot of flooding round us recently and I was wondering if anyone had experience of damage to the underneath of the vehicle from driving though flooded roads. The water tanks and gas tanks are fitted underneath our AS Symbol and they get exposed to splashed water all the time when its raining but what happens if part immersion occurs when driving through flood water on the road? Where are the vents on the tanks for instance?

by MalMonty Sun Oct 13, 2024 1:16 am

This is good advice: https://www.carwow.co.uk/blog/driving-through-flood-water

Personally, I'd avoid water above the tyre rim at all costs. Even then, slow and steady to the point you make very little movement in the water. Worth noting, insurance companies very rarely pay out on someone wrecking their car due to deliberately driving into flooded areas.

by Dbvwt Sun Oct 13, 2024 2:18 am

“Where are the vents on the tanks for instance?”

On the top, might be a problem if they were on the bottom! Sorry for my poor attempt at humour smile!

by Roopert Sun Oct 13, 2024 6:47 am

MalMonty wrote:Even then, slow and steady to the point you make very little movement in the water.

And even then you have to be aware that there's a chance that coming the other way through the flood will be someone who subscribes to the "nice and fast to push all of the water out of the way" method. This happened to me earlier in the year when an HGV decided that he didn't want to queue up to go round a flooded area - he went straight through it at about 40MPH, which almost drowned my poor little car.

by clarkescribe Sun Oct 13, 2024 7:53 am

All very well saying don't drive through flooded roads but if the campsite is on the Norfolk coast there isn't much option when there is only one road back out. It's not something I would do from chose but it would be good to know how deep is too deep.
I know how deep I can go with both our cars and even once found that my old BMW would actually start to float and loose traction if the water got too deep - it didnt do it any harm as it was fresh water and it didnt get into the electrics. The end of road I live on floods too deep to get out off every now and then so I'm aware of the depth limit with our cars but not our van. As to vehicles comming the other way - I just wait untill the road is clear. Rim deep is good as an optional limit but what I really want to know is how deep before something bad happens.

by Tinwheeler Sun Oct 13, 2024 8:18 am

I guess you’d need someone who’s driven through too deep water to answer that! The trouble is, you often can’t tell how deep the water is until you’re in the middle.

Have you crawled underneath and had a good look around, or asked someone else to do that for you?

by The Bargee Sun Oct 13, 2024 8:44 am

The real question might be “do you know how deep the flooding is?” Unless you know a road really well you could be forgiven for not realising that there is a hollow at some point. It only takes one deep hollow to catch people out. We have one such car trap near us, which catches lots of people out. It nearly caught me out once in a brand new Discovery, and I had driven the road regularly for about 15 years before that so should have known about it. Just got through, very much by good luck, but the water was up to the windows.

The best advice I think is that if you must go through get somebody to wade through in front of you to check the depth, ideally with a stick to sound the depth and for support. That is of course presuming that there is no current.

The Sevel vans seem to have quite a high engine air intake, so there may be little serious terminal risk to the engine itself. The alternator might not like getting wet. Not sure where the vehicle electronics are. A real problem will come if you soak the floor and furniture, and get the Sargent wet, remembering that water will flood in through the gas drops etc.

I have risked my 4x4’s in floods frequently, from absolute necessity on occasions, but I would not take the van through deep water, or water of unknown depth. The damage could prove very expensive. Malmonty’s advice makes good sense.

by Tinwheeler Sun Oct 13, 2024 9:03 am

“It only takes one deep hollow to catch people out”

Or a pothole!

by MalMonty Sun Oct 13, 2024 11:59 am

clarkescribe wrote:All very well saying don't drive through flooded roads but if the campsite is on the Norfolk coast there isn't much option when there is only one road back out. It's not something I would do from chose but it would be good to know how deep is too deep.
I know how deep I can go with both our cars and even once found that my old BMW would actually start to float and loose traction if the water got too deep - it didnt do it any harm as it was fresh water and it didnt get into the electrics. The end of road I live on floods too deep to get out off every now and then so I'm aware of the depth limit with our cars but not our van. As to vehicles comming the other way - I just wait untill the road is clear. Rim deep is good as an optional limit but what I really want to know is how deep before something bad happens.

"how deep before something bad happens"

You need to avoid water entering the engine, exhaust or any other inlet/outlet venting systems your van has fitted.
Also consider the positioning of EHU point or water getting into the overflow of your underslung freshwater tank [don't want to be drinking sewerage water]
There's also a lot of electrical cables running under some vans. All should be well insulated etc, but after a few yrs
can you be sure that driving through water isn't going to compromise anything? Each to their own, but I just park
up for a few mins and think about alternative routes. Worst case scenario, I'd rather abandon my vehicle for 24hrs
if there's no other option. A bit inconvenient, but 100% guaranteed I've not done any damage, temporarily or
permanently to the van.

by RML Sun Oct 13, 2024 5:11 pm

Most motor vehicles are only water resistant from the top down not the bottom up.
Rich..

by The Bargee Sun Oct 13, 2024 6:15 pm

RML wrote:Most motor vehicles are only water resistant from the top down not the bottom up.
Rich..

I won’t mention damp motorhomes but I do try and avoid buying cars with sunroofs. I have had too many impromptu showers from those!

by Kemerton-bath Mon Oct 14, 2024 7:53 am

Those of us with the underslung Whale space heating system that AS currently fit in their van conversions need to take this into account when determining water depth. I’ve just booked our van into Propex to replace a suspected failed gas flue fan on return to UK next week and their first question was whether we had driven through any water.

We haven’t, but them posing the question suggests it’s a known problem.

Tim

by Caraman Mon Oct 14, 2024 6:20 pm

I am extremely wary of driving through water. As I youngster I drove through a flooded road without realising how deep it was and at too much speed causing the engine to cut out. I had to remove my shoes and socks and roll up my trouser legs and, standing in the cold dirty water, dry the ignition plugs/leads and distributer with whatever I could lay my hands on. Eventually I got the engine to splutter into life again and was able to drive out of the water. Now if I am forced to drive through water I slow down to a snail's pace and if I know the water is deeper than say the wheel rim, I will try and find a different route.

by v8oholic Mon Oct 14, 2024 9:07 pm

Kemerton-bath wrote:Those of us with the underslung Whale space heating system that AS currently fit in their van conversions need to take this into account when determining water depth. I’ve just booked our van into Propex to replace a suspected failed gas flue fan on return to UK next week and their first question was whether we had driven through any water.

We haven’t, but them posing the question suggests it’s a known problem.

Tim

Apart from the flue, there's mains electricity as well to consider, if hooked up and switched on afterwards. While I'm confident that it's sufficiently sealed to keep out heavy motorway spray, actual immersion might be a different story.

by Sally Mon Oct 14, 2024 11:13 pm

Can I ask please, when people are saying “only to the wheel rim” do they mean the edge nearest the road, at 6 o’clock, so a few inches deep, or the wheel rim edge furthest away from the road, at 12 o’clock, so well over a foot deep.

I’m assuming people mean the second?

by Caraman Mon Oct 14, 2024 11:45 pm

Definitely not the 12 o'clock position which on my motorhome wheels would be about 1 foot 9 inches of water. I would be uncomfortable with anything over 6 inches of water.

by Roopert Tue Oct 15, 2024 1:09 am

Same here - more than 6 inches and I'll usually just back out again, unless I can see from other people's crossings that it is no more than that for the whole way.

It's not worth the risk, because if you cause major damage it may not be covered by insurance. The Ins companies are likely to consider it to have been done by the driver's choice and so it is not considered to be an accident. An acquaintance did serious damage to his car's engine, and he was £5k+ out of pocket, with no insurance payment.

by Sally Tue Oct 15, 2024 2:12 am

I’m just surprised at the suggestion that it’s only okay up to the rim. So assuming as said above that it’s the lower rim, that means only a few inches of water. I appreciate I’m being naive, but to me that seems nothing, for a car or van. I would have driven through water that covered the rubber on the tyre without a second thought (not at speed obviously, dead slow). So I’m wondering what I’m missing.

It’s a genuine question by the way, and I accept it may be me.

by Roopert Tue Oct 15, 2024 4:46 am

The main reason I have for not going beyond six inches depth is that it gives plenty of leeway for potholes, road camber and road dips that aren't obvious from the surroundings, plus it means that you can cope if some idiot turns up and plunges in at speed from the opposite direction before you're through.

On some vans the height of the air intake is obvious, and if you know that in your van it's a long way above wheel height them there's less risk, of course. And if you know that your specific conversion doesn't have anything sensitive hanging down underneath you have less reason to worry. On both of our vans, the diesel space heater is inside, above van floor level, so we (thankfully) don't have that to worry about.

by v8oholic Tue Oct 15, 2024 4:55 am

The wading depth for the Ford Transit is said to be 600 mm and I don’t see why the Boxer would be too much different. However I wouldn’t want it to reach as high as the things mounted under the van.

by Askit Tue Oct 15, 2024 5:11 am

I get what is being said about how much water folk would go through, the problem is you don't always (or ever?) get to measure the depth before advancing. Last year we were heading up Sutton Bank when seriously heavy rain caused flash floods with vehicles going in both directions trying to negotiate them. We reached a point where the water appeared well over a foot deep and the vehicle at the head of the queue coming down stopped. A lorry in front of me pushed through on the centre of the road and I went through on his tail. Did I think it was a risk, yes but the alternative (those who know the road will understand) seemed just as problematic. I had to dry out the 'wet locker' but what's new.

by Roopert Tue Oct 15, 2024 5:15 am

v8oholic wrote:The wading depth for the Ford Transit is said to be 600 mm and I don’t see why the Boxer would be too much different. However I wouldn’t want it to reach as high as the things mounted under the van.

I don't think that can be right, as a generalisation of all Ford Transits. On RWD Transits, anything that submerges the diff would produce significant risk of contaminating the diff with water - so that would be anything that's a bit deeper than the centre of the wheel hub. The diff vent can (supposedly) pull in quite a lot of water in a short time, because the diff and oil will be warm upon entry to the water, and the casing will be cooled quickly, drawing water from outside - though I confess I've no idea whether this is tested fact, or just speculation!

by Caraman Tue Oct 15, 2024 5:23 am

Sally wrote:..... I would have driven through water that covered the rubber on the tyre without a second thought (not at speed obviously, dead slow). So I’m wondering what I’m missing.

It’s a genuine question by the way, and I accept it may be me.

My van is on jacks at the moment but if it was not and the water level covered the rubber on the tyres I am pretty sure the water level would be up to the motorhome's wooden floor which is full of holes for wires, pipes and gas dropouts. Some of Sargent's wiring harness with its spade connectors would be underwater as would the fresh and waste water tanks and their pipes, breathers, insulation & heaters, the underslung gas tank and regulator and in my case electrically operated levelling jacks and their control box which is bolted onto the underside of the floor. None of these are designed to be immersed in water let alone water that is flowing due to the motion of the vehicle, wash from passing vehicles or if it is part of a river which it can often be on a flooded road. Again I haven't checked it but I am pretty sure if the water level covered the tyres' rubber it would be significantly above the lower cab door seals and close to the AdBlue & diesel filler. If I drove my Honda Jazz with water covering the rubber on its tyres, the water level would be halfway up the doors. I shudder to think what harm could be done to its hybrid electrics let alone its petrol engine.

by v8oholic Tue Oct 15, 2024 5:23 am

I was referring to the current Transit, which is front wheel drive, and therefore somewhat similar to the Boxer. In Europe at least, the last RWD Transit was built 25 years ago, wasn’t it?

by Roopert Tue Oct 15, 2024 5:31 am

v8oholic wrote:I was referring to the current Transit, which is front wheel drive, and therefore somewhat similar to the Boxer. In Europe at least, the last RWD Transit was built 25 years ago, wasn’t it?

Apparently not - I believe both Mk6 and Mk7 Transits were available in both FWD and RWD configurations, though whether all variants were available in the UK market I don't know.

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