Cranking car - do I need to disconnect ignition first?

I'd probably just remove the distributer cap with all the leads attached. It's not strictly necessary, but you're less likely to give yourself a jolt that way.

Remove them all together. Don't forget to mark the leads first! I use little notches in the ends of the soft insulators, made with a Stanley knife. When you crank the engine, if there's much water in there it can come out with one hell of a force. You don't want to be staring into the plug holes when it does!

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Probably wise - it'll stop any fuel getting squirted in. All plugs at once.

However - if the engine was running when you came out of the flood then it's too late to worry - there's no point in trying to get the water out, any that was coming will already have come.

So how does the water actually do the damage. I thought it was to do with a hot engine coming into contact with cold water and causing some kind of internal fractures in the metal. Is this wrong?

Is there only one way for the water to enter the engine, that is through the inlet inside the air filter housing which sits on top of the engine (carberettor type)?

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No, it's 'cos the piston coming up with the valves shut on a compression stroke is expecting to find nice compressible fuel-air mixture, not a quarter of a pint of incompressible water.

You can take your pick of what damage this does, but it's usually a bent con-rod and/or worse.

So - once the engine's been turned more than two revs with water in it, it's too late to worry whether there's any water in the bores. Last time I had water in the bores it was 'cos a head gasket I'd been neglecting for months finally let go overnight and allowed one bore to fill right up. The engine wouldn't even turn over and the starter isn't powerful enough to do any damage. However, if the engine had been running when a bucketload of water found its way in the energy stored in the flywheel (and running gear and momentum of the car if moving) is /more/ than enough to do loadsa damage.

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In terms of compression damage, yes, assuming you've not got a head gasket failed.

In terms of other damage - well, I suppose if you immersed the engine for a while you might well fill the sump up with water, but the dipstick'll tell you whether that's a significant problem.

The damage is caused when the cylinder has water in it and the piston tries to compress whatever is in there as it comes up the bore just before the sparkplug ignites the mixture. Water being a lot less compressible than gas means it effectively stalls the piston; wrecking the rod bearings, blows the head gasket apart, punch holes in the top of the piston etc. etc. It can even show up casting\manufacturing faults in the block/piston liner/head by causing them to crack but not due to fast cooling.

Chris

saw a cavalier where the bottom of the block had cracked off after a swim :O)

I never heard of this problem, all my toyotas never stalled when i put my foot down thru deep water, and i mean deep, only thing i thought of was damaging wheel alignment.

Guess i got lucky, wont do it again.

Stanley

Bearing this in mind the water may travel a long way, and is likely to be dirty. It could go 10 foot in the air, and cover the whole length of a garage. You should've seen the mess I made with redex :-)

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It depends where the air intake is. On some models of the Espace, for example, it's particularly low - less than a foot from the floor, so wading a deep puddle can bring a sudden bang'n'stop. My car's got the intake almost 3' off the ground. If I go paddling that deep it'll be not far off the bottoms of the windows and I'll have other things to worry about.

This was 4/5 few days ago now, wasn't it? I very much doubt there's any water left on top of the pistons, if there was any in the first place.

Is there any water on the dipstick?

Si

Well the car is outside, but still I want to minimum the mess if possible. It won't start shooting oil out liters of oil will it if there is no water in it for as long as I crank it?

I guess any water that comes out will be mixed with oil and black? I am getting apprehensive to do it now. Ways to minimize the mess? Am more concerned about oil stains all over the road or any where else it lands on.

The water wont be all that oily, unless your engine was seriously sick before it hit the flood! The oil is below the pistons, the water (if any) is above. After this time, the water is more likely to be red than black!

As for the ignition, some types of electronic ignition can be damaged if run with the HT side of the coil open circuit, so it is wise to disconnect the low tension side of the coil when cranking (i.e, pull the little wires or small plug off the coil)

Didn't notice any water as such on the dipstick, but the oil did seem a bit watery when smudged on the end of finger, but then again am not sure what the normal consistency should be. (Black 10/40 oil). I drained the oil and put fresh in. I don't think water in the sump is going to appear clear as the tap on the dipstick is it?

On checking the radiator cap there did seem to be a few globules of something reflecting in the light. Not sure if that's related to this incident or not. Was no mayo when the old oil came out or around the filler cap. When the old oil was draining it was all black, but then again I don't suspect it would look like perrier water would it?

Well I don't really want to take short cuts if water could be in the pistons.

Red from rust you mean? Would they really rust that quickly? The electronic ignition is described as "Electronic, with centrifugal and vacuum-controlled advance".

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If it ran at all after going through the puddle then there won't still be water on top of the pistons.

Well I don't suppose there is any harm in trying it? So if there is no water nothing will come out?

It would only take a couple of days for the water to start going rusty coloured. Don't worry about the rust doing any damage it will just be very slight surface rust at this stage, and will be polished off as soon as the engine starts. To be on the safe side, disconnect the LT side of the coil.