What happens when you drive a car through deep water

thexav

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I see the flooding on TV and lots of cars getting stuck in the water.

What happens to a car engine when you drive through deep water? Does the spark plug get wet and is then unable to make a spark.

Or does something more sinister go on?

Why do some cars like rally cars and 4x4's go through very very deep water without a problem when everyday cars just get stranded?
 
The big problem is sucking water through the air intake into the engine.

Air compresses nicely, water however does not compress so the pistons basically collide with the water which can't be compressed and it will typically bend con rods, destroy the pistons, break the crank or worse!

In many cases the car electrics will short and blow fuses, before the engine takes in water and dies. Allowing the car to thoroughly dry out and turning it over to see if it's mechanically sound before starting it, you stand a chance of getting away with it.

Splashes can be as catastrophic as going through deep water. Revs high, speed low is the mantra when driving through deep puddles and shallow water.

To go through deep water you need a snorkel. As long as the engine can breathe ok and the electrics are well sealed it will be fine.

Note that water can be sucked into the engine through the exhaust if you stall it.
 
Most ordinary motorists seem to think that faster is better when they encounter flooded roads and many end up with wet ignitions and no go.

In fairly deep water say up to axle level one should fix say a coat small tarp or whatever over the grille so it will restrict water entering the engine bay and drive thru at a steady speed like a fast walking pace in say 2nd gear and NEVER EVER disengage the clutch.

Also if possible drive on the crown of the road as it should be less deep there.

Way back when I competed in rallies in the 70's we used to fit a rubber glove over the dissy with the leads thru the fingers and sealed or taped where they came out after waterproofing the electrics including the fuse box with WD40 or RP7.

Of course if you have a diesel then it only needs air to keep turning over no matter how deep the water is BUT I have seen a 4wd float with water 1/2 way up the door.

Obi we will have to agree to disagree on the hi revs bit as that will force more water thru the grille IF it is not covered and into the high reving fan blades Sorry .

PS if you haven't seen others drive thru then it is prudent to get out and walk thru first th check the depth washaways etc.
 
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Obi we will have to agree to disagree on the hi revs bit as that will force more water thru the grille IF it is not c
I don't think I've ever owned a car where the fan blades spin in proportion to the engine revs. Most I've had only spin when the engine gets hot and they don't spin any faster, it's usually an on or off affair.

Perhaps it's just an Audi thing, always interested to hear other points of view and experiences, it gives me a more rounded out view of things.

I'm not talking about top third of the rev band anyway, you just don't want to stall it, and rather than trundle through at 10mph in 3rd gear, I would feel safer in second or even first gear.
 
Showing my age with belt driven fans and distributors .V(

Obi I am sure we are on the same page but express our point of view slightly differently at times |B
 
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I once lost an engine coz of a puddle , sucked water trough the air filter into the intercooler n hydrolock the engine . Was a good excuse to get a bigger turbo n bore out the engine
 
I see the flooding on TV and lots of cars getting stuck in the water.

What happens to a car engine when you drive through deep water? Does the spark plug get wet and is then unable to make a spark.

Or does something more sinister go on?

Why do some cars like rally cars and 4x4's go through very very deep water without a problem when everyday cars just get stranded?
You learn to scream obscenities
 
I once lost an engine coz of a puddle , sucked water trough the air filter into the intercooler n hydrolock the engine . Was a good excuse to get a bigger turbo n bore out the engine
I like your thinking @Rick4wd - don't tell me it was a complete accident, it just gave you a reason to give to your other half! ;)
 

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