Just curious. How can water get into a gearbox? Citroen Xantias had low mounted air intakes. The water would enter and stop the engine.
Irrelevant really as the water entered the gearbox and it would eventually seize...
People who drive normal cars through flooded roads have no common sense
Just curious. How can water get into a gearbox?
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They'll usually have a vent. Think about it, they get cold and warm. The air inside contracts and expands. You don't want air pressure inside trying to force the oil out through various seals.
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They'll usually have a vent. Think about it, they get cold and warm. The air inside contracts and expands. You don't want air pressure inside trying to force the oil out through various seals.
Thank you. So what prevents the oil escaping through the vent?
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>> Thank you. So what prevents the oil escaping through the vent?
It's at the top!
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>> Thank you. So what prevents the oil escaping through the vent?
It's at the top!
Okay the vent is on top, but why cant the oil be forced out through the vent, especially as there is pressure in the gearbox. I can see by your exclamation mark that you are getting narked but I am really just curious /interested.
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The same reason engine oil doesn't pour out of various breathers, It's designed that way.
The gearbox isn't full of oil, there's air space.
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The same reason engine oil doesn't pour out of various breathers, It's designed that way.
The gearbox isn't full of oil, there's air space.
Okay ..yes I see that.
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I have common sense, in the rare event I'm forced to wade in a "normal" car I change all the fluids ASAP afterwards.
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My 305 diesel estate had the air intake as high as possible therefore not a problem in floods. I knew someone who had a 406 diesel from new. They drove it into a flood and wrecked the engine as the air intake was very low.
Before the 305 I iwned a Corolla 1.3 GL. One day I drove though a flood so deep that a bow wave broke at windscreen base level. I kept going with nothing untoward happening.
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There are a lot of people with "common sense" here, but I thought cars were designed for those not so gifted. Hence warning lights for seat belts and lights left on and parking sensors and self parking. Soon we will automatic braking. So why is so much to ask that air intakes are a bit higher than just behind the bumper -forget CAIs. People make mistakes even those with common sense.
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The low air intake trend surprises me, okay it makes the engine more powerful by picking up colder air near the ground, but that greater volume of air requires greater volumes of fuel to go with it - surely bonnet level intakes would reduce fuel consumption slightly, would stop cars blowing up due to wading - at the cost of a tiny reduction of power most drivers wouldn't even notice.
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The low air intake trend surprises me, okay it makes the engine more powerful by picking up colder air near the ground, but that greater volume of air requires greater volumes of fuel to go with it - surely bonnet level intakes would reduce fuel consumption slightly, would stop cars blowing up due to wading - at the cost of a tiny reduction of power most drivers wouldn't even notice.
The ECU adjusts the fuel/air mixture continuously and even compensates for air density so economy is dictated by the throttle position, not the intake height - in any car turbo engines can get all the air they want and more.
Car drivers should be more realistic in their expectations of the safe wading depth of an ordinary car - once the water is above the bottom of the sills it's starting to float (albeit badly) which will reduce traction as the weight comes off the driving wheels.
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In theory you are correct, however experience says that cars use more fuel in cold weather, even ones used on long journeys where the extended cold start cycle has less impact on the equation. The difference in temperature between bonnet and sill height can be as much as 3C. The driver will drive the same way and will burn more fuel if the intake temperature is lower. Every car I've ever had (over 50 cars so far) uses more fuel in the winter, even the ones where I've fitted a block (coolant) warmer do. I've been at the sharp-end of engine management software development - I've seen enough data to know this as a fact. The ambient temperature of the air intake is factored when calculating how much fuel to put in a Formula One car at the start of a race - it makes a difference regardless of how much the car's engine management system compensates.
The majority of cars still have driver-operated throttle butterfly valves, when you prod the throttle the EMS must supply enough fuel for the airflow you have demanded - if the air is colder (denser) then more fuel will be supplied - it is that simple. If the average human being was sensitive enough to always accelerate at 0.2G and presses the throttle precisely enough to acheive this exact rate of acceleration, then yes, the fuel consumption will be no different as there will be less throttle required to achieve that acceleration rate when air is denser - reality doesn't work like that - and of course when he demands full-throttle the ambient temperature and altitude determines the fuelling - not the throttle.
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Every car I've ever had (over 50 cars so far) uses more fuel in the winter,
This is because the oil is more viscous increasing engine, gearbox and wheel bearing friction. Pushing a warm car off the ard shoulder is a doddle. Trying to push a cold car is hard.
The tyres are colder which means the rolling resistance is higher. The air is denser therefore aerodynamic drag is greater.
The "cold air makes power" theory is only true at WOT-which you don't often use. For a given output you simply use a smalle throttle opening than you would in warm air.
The difference in temperature between bonnet and sill height can be as much as 3C.
The effect of 3C on air density and knock resistance is utterly trivial. In fact, on a hot day, the air near the hot tarmac will be considerably warmer than air higher up.
CAI have been the norm since carburettors and SPI were discarded in favour of multi point injection. This hand wringing about the location of the air intake is ridiculous. Itr has more to do with the available space in a tight engine bay than any trivial performance benefit.
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Okay, ignoring the fact that you have bailed-out on talking b******s earlier on about petrols and snorkels. If the difference of 3C is so trivial - why have all the manufacturers - across the board - gone for bumper-height air intakes? If it is a trivial difference then surely safety would take precedence over performance and efficiency?
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why have all the manufacturers - across the board - gone for bumper-height air intakes?
Aerodynamics, ie reduced fuel consumption - reducing the number/area of higher apertures.
It's not across the board - SUVs still have the CAI at respectable height - but then they're bought by people who may need to wade through water at some point.
I had cars, not SUVs for 40 years and wouldn't dream of going through water more than 6" deep, ie sill level - and if I couldn't see how deep it was I wouldn't go through it.
James Bond's Lotus Esprit has a lot to answer for - everyone seems to think their car will emulate it so they stupidly drive through water that's too deep or just unknown depth.
Edited by RT on 23/11/2012 at 08:43
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Okay, ignoring the fact that you have bailed-out on talking b******s earlier on about petrols and snorkels.
The vast majority of snorkels are there for looks. People like the rugged real off-roader look. Simples. Marine spark ignitionengines are always careful to site exhaust cooling sufficiently far downstream to prevent water being drawn into the engine. They don't use snorkels on the intake though!
as RT says, the location of the air intake has probably got more to do with aerodynamics and space than anything else.
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No, you are talking nonsense,I've seen many petrol cars as well as owned a few, with snorkels which wade with completely submerged exhausts. Your original statement was wrong about petrols with snorkels, you are wrong. As petrol engines have massively lower compression ratios they are more likely to get away with ingesting water without causing mechanical failure. But of course you can never be wrong - even when you're wrong.
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As petrol engines have massively lower compression ratios they are more likely to get away with ingesting water without causing mechanical failure
Water is (to a first order approximation) incompressible. So if the amount of water ingested into a cylinder is greater than the clearance volume, something is going to give. Compression ratio is only relevant to compressible fluids.
Petrols have a throttle which, when (almost) closed, provides a formidable obstacle to water. Generally, diesels do not.
I've seen many petrol cars as well as owned a few, with snorkels which wade with completely submerged exhausts
Sure. If you keep your foot on the gas to keep the exhaust velocity high, no problem. When intentionally wading, this is what you do. But most people who unitentionaly end up wading lift off-this is the only time flow reversion through the exhaust occurs.
Moreover, you're talking about Buick V8s with log manifolds exiting via a single pipe. A 4 cylinder engine or a v8 with a true dual exhaust system is considerably more prone to water ingestion via the exhaust.
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As petrol engines have massively lower compression ratios they are more likely to get away with ingesting water without causing mechanical failure
Water is (to a first order approximation) incompressible. So if the amount of water ingested into a cylinder is greater than the clearance volume, something is going to give. Compression ratio is only relevant to compressible fluids.
Petrols have a throttle which, when (almost) closed, provides a formidable obstacle to water. Generally, diesels do not.
I've seen many petrol cars as well as owned a few, with snorkels which wade with completely submerged exhausts
Sure. If you keep your foot on the gas to keep the exhaust velocity high, no problem. When intentionally wading, this is what you do. But most people who unitentionaly end up wading lift off-this is the only time flow reversion through the exhaust occurs.
Moreover, you're talking about Buick V8s with log manifolds exiting via a single pipe. A 4 cylinder engine or a v8 with a true dual exhaust system is considerably more prone to water ingestion via the exhaust.
The previous comments about back limiter flaps on chevy-powered boats applies to litigation-sensitive manufacturers, I've known (and owned) many, many DIY installations without similar precautions which run forever. As soon as the engine is running the submerged exhaust system becomes pressurised, the "negative pressure" pulses simply become lower pressure pulses, even with the throttle closed.
Again I must point out that all varients, petrol or diesel, of the current Range Rover have a 900mm wading depth - which completely submerges the exhaust system, none of them have back-limiter or "flap valves" in the exhaust system, the bonnet-level air intakes are certainly not ostentatious decorations.
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There are a lot of people with "common sense" here, but I thought cars were designed for those not so gifted. Hence warning lights for seat belts and lights left on and parking sensors and self parking. Soon we will automatic braking. So why is so much to ask that air intakes are a bit higher than just behind the bumper -forget CAIs. People make mistakes even those with common sense.
You are joking of course. Many motorists don't realise they have no spare wheel and if they do have one, have no idea how to change it...
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There are a lot of people with "common sense" here, but I thought cars were designed for those not so gifted. Hence warning lights for seat belts and lights left on and parking sensors and self parking. Soon we will automatic braking. So why is so much to ask that air intakes are a bit higher than just behind the bumper -forget CAIs. People make mistakes even those with common sense.
You are joking of course. Many motorists don't realise they have no spare wheel and if they do have one, have no idea how to change it...
Exactly my point
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QUOTE:...""People who drive normal cars through flooded roads have no common sense""
Very low mounted air intakes are a newish thing, I think.
Any of us on here might have, say, hired or borrowed a car and been unaware that its air intake was mounted at bumper level - and faced by a flooded road which other cars were coping with, we might have assumed we'd be OK.
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QUOTE:...""People who drive normal cars through flooded roads have no common sense""
Very low mounted air intakes are a newish thing, I think.
Any of us on here might have, say, hired or borrowed a car and been unaware that its air intake was mounted at bumper level - and faced by a flooded road which other cars were coping with, we might have assumed we'd be OK.
Many older drivers who are not familiar with modern under the bonnet layout and assume the air intake is high up - I did until I took a closer look. Then there are the vast majority who never look under bonnet today as DIY on cars is a thing of the past; don't do basic checks like oil and tyres, cant change a wheel etc. so naturally are blissfully unaware of the risks of going through even slighty flooded roads depending on how low the air intake is.
Once stranded the situation could become life threatening if the water is rising, for example crossing a ford and being swept way.
So taking into account ignorance and the risks motorists take, (like any other safety facility in the vehicle which take into account the human factor), air intakes should not be so low as to aid this hazard.
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This seems to be yet another area where the Eurobox manufacturers have decided to put the air intake low down (the Ford Focus/Mondeo is another example) whereas the Eastern makes are still taking the sensible approach of placing it above the radiator at the front of the engine bay.
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If I'm crossing a ford, I always check the depth gauge - if I'm faced with a big puddle or worse I need to see the a reliable guide to it's depth, kerb or other car.
What I never do is drive into water of unknown depth - simples!
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So taking into account ignorance and the risks motorists take, (like any other safety facility in the vehicle which take into account the human factor), air intakes should not be so low as to aid this hazard.
How many people do you directly know who have hydraulically locked an engine?
What height is the airbox. I bet that is reasonally high-even if the air intake is not. Take the filter out of the box. There may well be holes in the bottom of the box, so if the intake becomes submerged, the engine will just draw air directly into the box. Big fuss about nothing.
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Back in '79 I "parked" my Hillman Imp in a flooded ditch, water up to the window line, overnight - when it was dragged out next morning it started 1st time and our only concern was dilution of the engine oil - most of the water was evaporated off on the journey home where we changed the oil.
Do modern cars have such perfectly fitting intake valves, exhaust valves and piston rings that hydraulic pressure is actually a problem ?
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Do modern cars have such perfectly fitting intake valves, exhaust valves and piston rings that hydraulic pressure is actually a problem ?
If they didn't fit so well, the engine wouldn't run.....
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If it swallows water while it's running, it's going to do a lot of damage. Diesels are going to be worse than petrols because of the smaller combustion space and resultant higher compression ratio. Bent con rods quite likely, crankshaft out of true possible. Pistons with stressed crowns and distorted skirts and cracked piston rings.
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Diesels are going to be worse than petrols because of the smaller combustion space and resultant higher compression ratio.
Also the Diesel will keep running until ingestion of water stops it, while the petrol usually stalls as water reaches the electrics well before that happens.
I've personally pulled a petrol car out of deep water, sprayed WD40 on the electrical bits, spun the engine over with the plugs out to spit out water and then started it. No lasting damage bar the sodden upholstry.
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How many people do you directly know who have hydraulically locked an engine?
What height is the airbox. I bet that is reasonally high-even if the air intake is not. Take the filter out of the box. There may well be holes in the bottom of the box, so if the intake becomes submerged, the engine will just draw air directly into the box. Big fuss about nothing.
I friend has written off two engines by going through a flood. Using his company's van , under pressure to get his calls done he has taken the risk.
But a vehicle will eventuaslly stall hydrolock or not with resulting repair costs, you this every night on the news currently.
Edited by pullgees on 23/11/2012 at 22:24
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I friend has written off two engines by going through a flood. Using his company's van , under pressure to get his calls done he has taken the risk.
But a vehicle will eventuaslly stall hydrolock or not with resulting repair costs, you this every night on the news currently.
Perhaps you know too many people with poor judgement when it comes to driving through floods which are too deep.
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I friend has written off two engines by going through a flood. Using his company's van , under pressure to get his calls done he has taken the risk.
But a vehicle will eventuaslly stall hydrolock or not with resulting repair costs, you this every night on the news currently.
Perhaps you know too many people with poor judgement when it comes to driving through floods which are too deep.
Huh? What has that got to do with the discussion?
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Perhaps you know too many people with poor judgement when it comes to driving through floods which are too deep.
Huh? What has that got to do with the discussion?
It highlights that if people drive in inappropriate conditions that there are consequences which are unreasonable to expect the car designer to prevent.
Cars aren't idiot-proof and never can be.
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There was one older gent who died this week trying to cross a ford in a 4x4 (I think) and being washed downstream...
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I used to work for a major manufacturer-it was astonishing how many people claimed to have destroyed their engines by driving thro' a half inch of water at half a mile an hour!!!
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There was one older gent who died this week trying to cross a ford in a 4x4 (I think) and being washed downstream...
That's correct, in Somerset where I live. I don't know the circumstances, maybe being in a 4x4 he thought he make it across the ford. He died on the way to hospital with heart a attack.
But this highlights what I've been saying throughout this thread, that you do get drivers for one reason or another be it lack of awareness of the layout of their engine compartment, or late for an appointment or under pressure from their firm, they will chance it. And like any other saftey feature on a vehicle, they are born out of these human weaknesses.
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>>There was one older gent who died this week trying to cross a ford in a 4x4 (I think) and being washed downstream...
Too many people think 4WD are 'go anywhere' vehicles.
How many do we get on here asking about 4WD for in case of a little bit of snow or they've got to drive up a wet hill? In the case of snow, Winter tyres are probably a better bet, unless the snow's at bonnet height, then a 4WD's not sufficient.
You'll still be stuck behind the RWD!
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Perhaps you know too many people with poor judgement when it comes to driving through floods which are too deep.
Huh? What has that got to do with the discussion?
It highlights that if people drive in inappropriate conditions that there are consequences which are unreasonable to expect the car designer to prevent.
Cars aren't idiot-proof and never can be.
Clearly you never make an error of judgement behind the wheel and of course you don't require any safety feature in your car as your not an idiot, it's the other drivers who are.
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Funnily enough I've just witnessed this earlier in the afternoon.
A '52 406 estate driven a little too enthusiastically through a ford that's a little higher than usual. Just made it out, engine died and a lot of nasty noises and steam from the engine.
He had a nice little crowd form (it was outside a coffee shop in a country house) before getitng towed away by an Isuzu. Made me laugh after reading this thread this morning
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Cars aren't idiot-proof and never can be.
Clearly you never make an error of judgement behind the wheel and of course you don't require any safety feature in your car as your not an idiot, it's the other drivers who are.
Of course I make mistakes, like everyone - I just don't blame the car or the designer for my mistakes.
Given the excessive speed that many drivers go through a flood, I don't think raising the intake would make any difference - it would still be below the level of the bow wave they create.
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Cars aren't idiot-proof and never can be.
Clearly you never make an error of judgement behind the wheel and of course you don't require any safety feature in your car as your not an idiot, it's the other drivers who are.
Of course I make mistakes, like everyone - I just don't blame the car or the designer for my mistakes.
Given the excessive speed that many drivers go through a flood, I don't think raising the intake would make any difference - it would still be below the level of the bow wave they create.
Forget about blame mistakes happen. Cars are crammed with designs that lesson the impact or avoid huhuman error. I'm suggesting one more and it's not for the benefit of the stupidest end of the spectrum of driver - they will always meet their cumupence one way or another.
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How long will it be before insurance companies refuse to cover damage caused by hydro-locking of engines,I wonder? The recent spate of flooding has probably got loss adjusters asking why they should cover people who are too stupid or ignorant to realise the potential damage that driving fast through floods can cause. Perhaps car handbooks could highlight the dangers for the white goods brigade.
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Only complete idioys drive through deep floodwater. Why should insurances companies repair damage caused by total stupidity.
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Only complete idioys drive through deep floodwater. Why should insurances companies repair damage caused by total stupidity.
The trouble is: often you have no idea the water is going to be ddep..
Which of course is a good reason not to drive through..
As for driving through fords in flood, that is Darwinisim in action I am afraid..
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How long will it be before insurance companies refuse to cover damage caused by hydro-locking of engines,I wonder? The recent spate of flooding has probably got loss adjusters asking why they should cover people who are too stupid or ignorant to realise the potential damage that driving fast through floods can cause. Perhaps car handbooks could highlight the dangers for the white goods brigade.
The same handbooks that advise checking oil, coolant, and tyres?
Yeah that'll work :-P :-D
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Saw a mixture of sensible, stupid and lucky driving at floods on our normal route to the pub for lunch - it's a regular place that floods so locals know the potential.
On the way there a Proton went through very slowly, sticking to the crown of the road, a Fiesta turned back (good logic - if in doubt, don't) so I followed though in a SUV with the benefit of higher clearance.
On the way back the water was obviously deeper with a couple of cars stuck, but being pulled out by a Suzuki Jimny - we then had to wait while a Discovery driver came through like an ijot with a bow wave above his already high bonnet - having seen the water's depth on the Jimny's wheels I went back through slowly followed by my son in a Vectra-C which was starting to float and losing traction but kept his head and made it.
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I ran through or rather round a large puddle in a dip yesterday. The driver who passed me went very slowly but I slipped off the kerb I was running in (it was only 10cms deep there).. and ended feet first in the side of the road. Water up to my waist.
The driver was lucky : he avoided the potholes..
(it was a rough country road)
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I did a short course on this - drove an old proper Land Rover. The guy running the course said never to drive through large patches of water because you never know how deep it is or indeed if there is a whopping big rock submerged in there....I took this as simple common sense!
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