Water in a petrol car

forgotmyname

Pew_Pew_Pew_Lasers! wrote: »

This is utter rubbish. Water doesn't compress, but neither does petrol.

Water will be pumped into the cylinders in exactly the same quantities as petrol - ie - practically nothing. So all that will happen is that the engine will refuse to fire, and the battery will go flat through trying to turn it over.

What you're talking about is when uncontrolled quantities of water get into the engine through the air intake. That hasn't happened here.

OP, drain the tank, change the fuel filter, refill the tank with petrol, keep the battery charged, and turn it over until it starts. It may be slightly difficult as the spark plugs may be slightly damp, and it will also depend on whether or not your fuel system is self-bleeding, but I very much doubt you'll have caused any damage at all, except to your pride.

When petrol gets injected the spark ignites it, Then gets ejected as a gas, Water doesnt so it will build up in the cylinder.
Exactly the same way when a headgasket blows.

If it was running then the speed of the combustion process will force the water out but cranking speeds it wont get ejected from the cylinder.

Kids used to wee in the fuel tanks of their off road scooters to make them go further, Whether they did or not is a mystery but they used to smoke like a steam train. If left ticking over they would cut out.

darich

bigjl wrote: »

Actually no, the water is more likely to force the exhaust valve shut, and the engine was running when the water would have been injected, you don't think that the temperatures in a running internal combustion engine are quite high do you, I do.

Have you ever heard of hydraulic lock, the most common case of this was in early DCI Clios, the air intake was very low to the ground, water was drawn up, through the air filter, into the engine, result bang, and no the water wasn't expelled out the exhaust valve in these cases either.

So, actually you are talking nonsense, please feel free to furnish us with your example of a car that ingested water, via the fuel system or induction system in the cylinders whilst running and not been damaged, as I have furnished you with an example that was well known at the time it happened, and yes Renault did try to pas the buck onto owners, even though the depth of the puddle which could cause damage wasn't actually that bad.

And don't mention"oliver" from topgear, though note they did expel any residual water by turning over with the plugs out.

The hydraulic lock you mention is a completely different issue from the one being discussed.
Hydraulic lock, as you you rightly state will cause severe engine damage.

However you also state, "the water is more likely to force the exhaust valve shut". So what happens when a head gasket blows and water enters the system? That doesn't cause the valves to shut. The car will continue to run despite the water in the cylinders.
Other damage can result and it obviously requires a repair but the car does run. In fact I'd suggest that depending on where the gasket is damaged, the car could run for many miles with a blown gasket provided levels are constantly topped up.

You also asked for an example of a car that has ingested water and not been damaged. I think most posters are in agreement here that some damage will have been caused even if the engine is ok - the fuel filter or pump may need replacing.

skiddlydiddly

Bigjl from what the OP says the car started, moved a few feet then cut out.I presume that it started using existing fuel in the pipes then stalled when the water hit.Even if the OP kept cranking over the engine without the water being able to escape a 1.6 engine isn't going to be able to squirt in that much water with what, maybe 200-250cc injectors?With hydrolocking its more water in a shorter time.
I'm not sure(genuinely don't know) what you meant about the water closing the exhaust valves though, I thought the cam opened and closed them?

bigjl

Surely water in the cylinder is water in the cylinder, when a head gasket goes it doesn't end up in the bores, just mixes in the coolant and the oil, some may be in the oil that lubes the bores, but this would be below the piston rings surely.

The reason for hydraulic locking of an engine is that water enters the engine from the top, either from the fuel or induction system, which is totally different to a head gasket.

Though it is entriely possible that an egine could blow the head gasket in such a way the water enters the bore above the pistons ans then I would think that hydraulic lock is a possibility, it depends how much water we are talking about, the engine can deal with small amounts, but only so much, if the too much water is involved then damage will result.

Note that even an interference engine can snap a cambelt without causing damage, would you recommend turning it over for a while just in case, no, as then you are guaranteed to damage it.

There is nothing wrong with taking a precautionary approach and planning for a worst case scenario, which would be treating the engine as though it has water in the bores, in other words, turning it over with the plugs out to make sure they water is expelled.

Actually I have seen a car with hydraulic lock after a possible head gasket failure, think it was a Fiesta with the 1.4 TDCi engine, when stripped there was loads of water in the bores, but the owner denied driving through water and as the water was in the bores it must have come from somewhere, cracked head, headgasket, something caused the water to get in there, never got to the bottom of it a new engine was fitted. The engine was definately siezed, as prior to stripping it couldn't be turned over atall.

bigjl

skiddlydiddly wrote: »

Bigjl from what the OP says the car started, moved a few feet then cut out.I presume that it started using existing fuel in the pipes then stalled when the water hit.Even if the OP kept cranking over the engine without the water being able to escape a 1.6 engine isn't going to be able to squirt in that much water with what, maybe 200-250cc injectors?With hydrolocking its more water in a shorter time.
I'm not sure(genuinely don't know) what you meant about the water closing the exhaust valves though, I thought the cam opened and closed them?

When the cam opens the valve the water can't be compressed so it will force all the valves closed, there is more force being applied upwards than the valve can cope with, the valve stem will usually bend.

This isn't me making this up, it is engineering fact.

skiddlydiddly

But if its compressed enough to do that wouldn't the pressure force it out into the exhaust manifold?Bearing in mind its a relatively small amount of water and it will take the path of least resistance.

I don't think you ar emaking it up btw, am interested.

Norman_Castle

From my understanding combustion engines run at a ratio of approx 20:1. (20 being air, 1 being fuel). Surely hydrolocking occurs when a large amount of liquid enters the engine, ie replacing the air rather than, as in this case, a non combustable liquid enters the cylinder in place of a combustible one. The ratio of 20,air to 1,liquid will remain the same. The engine will not fire because, unlike petrol, water does not burn. The unburnt mixture will be expelled through the exhaust valve in the same way the fuel air mixture would be in an engine with a non functioning ignition system.

bigjl

We are all getting a bit to focussed on what is basically a theoretical point, does anybody know how much water it would need to hydraulically lock and engine, the water contaminated the fuel, so it is entirerly possible that the engine ran with more and more water being injected, with the engine running rougher each time.

The engine still runs in the OP's situation and I introduced a possibility of hydraulic locking and valve issues as possible problems, the fact that the engine turns over means that it probably isn't siezed, but to take a belt and braces approach is sensible, and my point was that the OP shouldn't just turn it over incase water was in the bores, and how to make sure it wasn't, by turning over with the plugs removed.

Your point Norman is probably correct, but as nobody knows how much water is needed to lock an engine then why take the risk, and is water was always pushed out the exhaust valve then there would never be a concept of a hydraulically locked engine, yes a certain amount my be ejected, but tha fact the sometimes it doesn't means i must advise that the engine is turned over with the plugs out to make sure.

The Renault DCi engines mentioned where locked by a relatively small amount of water, that had also gone through the air filter, the engine involved this time is only 1600cc, so each cyclinder is about 400cc in capacity. How much is injected each time needs to be multiplied by the number of time water was injected. it is likely that contaminated fuel was injected more than once.

I still think that in the OP's position he should turn it over without the plugs as a precaution, any other advice than that is risky, we don't know what is in the bores.

Then change the plugs, try to drain the tank as much as possible, then refill to the top to reduce the amount of water that could be in there, much in the same way you would drain a misfuelled car.

Then change the fuel filter and give it a go.

Flying-High_2

bigjl wrote: »

Surely water in the cylinder is water in the cylinder, when a head gasket goes it doesn't end up in the bores, just mixes in the coolant and the oil, some may be in the oil that lubes the bores, but this would be below the piston rings surely.

.

So where does the White smoke/steam come from on many vehicles with headgasket failure?... Water in the bores being turned to steam.. Hence often the nice clean piston crown nearest the failure due to the steam cleaning action.

Flying-High_2

Firstly drain tank... Remove fuel hose at the Injector rail and turn it over without the plugs in...You should then get whatevers left in the fuel lines/pump out as its turning over... Use a bucket or something to catch it... It's not Ultra High pressure so the world wont stop spinning before bedtime.. Just use common sense.

If the fuel hose isnt dis-connected you'll be pumping whatevers in the fuel lines back into the engine and therefore !!!!ing in the wind.... You'll see when the fuel lines are clear as no more of the Water/Petrol coming out... Petrol in/Filter change and go from there... could also leave the injector rail hose off until the first trace of fuel and then if you have fuel that far then at least the pump lines etc looking at least OK