Engine water hammer
If there is a puddle on the road in front of the car, many inexperienced drivers tend to pass it at high speed so as not to get stuck and not to get water in the cabin. And it is a very serious mistake! Very often, flying into the water at speed, the car “rakes” a large amount of water into the engine and instantly dies, shuddering with the whole body.
This is the first symptom of hydrostatic shock – a dangerous breakdown, when water gets into the moving mechanical parts of the engine, which causes jamming and complete failure of the power unit. What to do in this situation?
What is a hydraulic shock, and how does it occur?
Engine hydraulic shock is a sudden ingress of a large amount of water into the engine cylinders, as a result of which pressure rises rapidly in the combustion chambers, the operating cycle is abruptly interrupted and the mechanically moving parts collapse.
If a car suddenly flies into a deep puddle, the water, which has a low compression threshold, pours into the engine under high pressure, slams into the combustion chamber and hits the piston that performs rapid compression of the combustible mixture inside the combustion engine cylinder at up to 6000 rpm. Breaking into water as into a stone wall, the piston breaks, crank rods and rods are bent, cylinder head studs are torn, cylinder head gaskets and timing belt are torn, the crankshaft is deformed. The engine is completely destroyed and cannot be repaired.
Sometimes the water hammer can occur due to breakdowns in the cooling system, cylinder-head gaskets burning through, carburetor or injector malfunctions: then coolant or too much fuel starts pouring into the combustion chamber, which will surely lead to water hammer.
How can you tell if a water hammer has occurred?
During hydroblow, the car shakes the whole body so that you can feel it with your body, sitting in the passenger compartment, after which the engine immediately stops. But there is hope: maybe the crankshaft position sensor just flooded with water. Let it dry out and cautiously try to start the car. If the engine will start – everything is all right, you can go further.
- Wet air filter is not a good symptom, but not critical.
- Drops of water on spark plugs – not a tragedy yet: The engine has “hobbled” with water, but its main units can remain intact.
- If the engine has stalled at idle (the car has crashed into a puddle on inertia) – it means a little liquid got into the engine, but most likely, there will be no critical damages.
It is important! Even with these questionable signs, it is necessary to deliver your car as soon as possible for diagnostics and to check a condition of the engine.
The first and rather dangerous symptom of hydrostatic shock is water standing in the case. At the very least you should disassemble it and drain the water, otherwise it will mix with the engine oil into an emulsion and provide dangerous oil deposits.
If you have run into a puddle at high speed, and the engine was working at high revolutions, and water covered the engine, after what the car strongly vibrated and stalled – the probability of hydro strike is nearly 100 %. This means that water got into the combustion chamber and knocked out the cylinder block.
Additional signs of water hammer:
- The air filter is waterlogged and deformed;
- in the cylinders there is a stepped layer of soot (almost wiped off on top, shiny traces on the bottom);
- the piston in the cylinder is lower than standard and has a heavy layer of soot;
- shiny wear bands are visible on the liners;
- the crankshaft cannot be cranked by hand and water is leaking from the spark plug seats.
In this situation it is impossible to start the engine – other mechanical units of the car may start to deteriorate. Evacuation to a service station is necessary.
What to do in case of water hammer?
Of course, the degree of engine’s destruction will depend on many factors – water quality, the amount of water in cylinders, the speed of the car and engine speed. However, it is better to immediately recognize that the car has received the maximum hydrostroke, and promptly act according to a certain algorithm:
- stop the car and put out the emergency stop signs;
- unscrew spark plug and check if there is water on it;
- disassemble the cowl and check the air filter for moisture;
- try cranking the engine crankshaft with the spark plug removed – if it cranks and no water leaks from the spark plug seats, then there is no critical damage;
- try cranking the engine with the starter – if there are no knocks, you need to purge the cylinders, screw in the plugs and try to start the car.
If the crankshaft doesn’t turn by hand, or you hear some extraneous noise while trying to crank it with a starter, it makes no sense to experiment further. If after such procedure and replacement of air filter the car will start and drive, you are lucky.
If the hydroblow was of small force, you may hope that not all cylinders are damaged, the piston rods were slightly deformed and one or two pistons are simply jammed in liners. In this situation, the pistons themselves and the connecting rods with pins will have to be replaced.
But, more often, in flooded cylinders the pistons are torn, the connecting rods are broken, the cylinder walls are punched, the gaskets are torn and the cylinder head is destroyed, the crankshaft is broken and the timing is torn, and cracks are created in the cylinder block. In this case, the engine would have to be replaced.
The situation with diesel cars is even worse. In “diesels” the combustion chamber is smaller, and less water is needed for hydrostroke. That is why, if the owners of gasoline cars still have a chance to get away with it, the injector cars are guaranteed to be completely overhauled in 95% of cases.
How to prevent a hydro strike?
The best way to keep your car engine from hydroblow is not to drive in puddles and keep the air inlet of the car from water. But if you have no choice, and you have to drive through a puddle, do it so that the water is no higher than half the height of the wheel.
When driving through puddles, try to move smoothly and at low speed, so that water does not rake into the air intakes. Add gas only after the deepest place has been passed.
If the water in the puddle was higher than necessary, it is better to stop and turn off the engine, and then try to pull the car out of the water cable. It is obligatory to diagnose your engine at once, at the first service station.
In conclusion it is necessary to note, that even insignificant for a car water obstacles should be overcome accurately if you want to avoid hydro strike which can destroy your engine in seconds, and drive you to long and expensive repair.
If you suspect a water hammer, immediately stop trying to start the engine, check the crankshaft position indicator, the condition of the air filter and spark plugs, and check the water level in the cylinder block. If you can not get away with blowing out the cylinders and drying the engine, the engine is likely to be replaced.
Author: Kiselev Ya.
How to avoid hydroblow? How to behave if you have got a hydroblow? The question is how to avoid hydroblow and how to repair the engine after it.
Hydrostroke is the ingress of water into the engine combustion chambers (usually through the air duct), with the subsequent impact of the engine pistons against this water plug, after which the engine fails. Water can get in two ways.
The first is when you “fly into” a deep puddle at high speed, the water is literally pressurized into the air filter, and then into the combustion chambers.
The second is when the water level is so high that the water itself flows into the engine air duct. It happens rarely, but it does happen, for example this type of water hammer has cars from the flooded areas of Europe.
Once the water gets into the engine cylinders, the following happens. Water is not compressible like fuel or air. After water gets into the engine piston, during the compression stroke (valves closed), the piston moving up rests against the water barrier (a kind of impact), the pressure inside the cylinder increases tens or even hundreds of times, but the engine tries to complete the cycle and tries to bring the piston to the upper point. Thus, the cylinder, where the water hit, stops almost instantly, bumping – hitting this water plug. This is where the hydrostroke occurs, respectively critical engine breakdowns, usually it is bent “connecting rods”, broken pistons or piston pins, but the most complicated breakdown is the engine block rupture, it happens quite often. Now imagine the pressure in the engine cylinders if the block ruptures.
– How to avoid engine hydrostroke?
Again, everything is simple.
1) You don’t need to “fly” through deep puddles at high speeds, there is a very high chance of getting water on the air filter and then into the engine cylinders.
2) Also, do not overestimate your car, when the small car, you almost float trying to overcome a deep puddle, like a small lake – the swamp.
In general, as the experienced drivers say, if it “pours like a bucket” and the roads turned into rivers, it is better to wait out such weather at home. The car will be safe, and you will save yourself from various troubles in the form of water pits. However, if all the same had to go, then remember one rule, the slower on deep puddles we go, the better. It is desirable if you go 5 – 7 km / h, in first gear, no more! Otherwise, it is better to bypass deep puddles!
How to behave if you have received a hydroimpact? Many people after crossing a deep puddle at speed, find that the engine has stalled. They try to start the engine (at first it may even revolve), and after “bang” and there is no piece of the block, or turn the ignition key, and the engine does not revolve! These are signs of an engine water hammer!
You have to be mentally prepared for it. For example – if you “flew through” a deep puddle at high speed and then the engine stalled, you should not try to start it, remember about engine hydrostroke! If you try to start it, and there is water in it, you just finish it off! There is one simple rule:
“If after crossing a large and deep puddle, your car stalled, this is the first sign of hydrostatic engine. In no case do not “twist” the engine, quietly go out and unscrew the plugs, and all of them, we do not know what cylinder we have water in. Take out the air filter cover and touch the air filter. After the spark plugs are unscrewed, now the engine needs to be tried “cranking”, if there is water in the cylinders, most of it will come out of the holes where the spark plugs were inserted. The engine spins, water comes out of the holes, consider yourself lucky! However, you do not need to tighten the spark plugs, call the tow truck and go to the service station, there should dry the engine cylinders and the engine finally, you can not do it yourself, at least because you need to remove water not only from the cylinders, but also from the air filter and air duct.
This is a lesser problem, after an engine water hammer, but it often happens that the engine does not spin or the cylinder block is torn, then only repair.
– Engine repair after water hammer.
To say it is expensive is not to say anything! It is very expensive! Okay, if you have bent “connecting rods”, it is half the trouble to change the whole piston and connecting rod group, which is not a little! But if you had a ripped engine block, then you will need not only a new cylinder block, but also a new piston and connecting rod group, plus all this needs a quality assemble and put in the end, the price will be very high.
Summing up in my article – hydrostroke of the engine, I want to warn you once again, well, you should not race on deep puddles, pass them accurately! Especially it concerns the PATHERS on the undervalued machines, such as “sports”, which are worn everywhere and always, slow down before a puddle, so that then it was not painfully painful, to restore the killed engine!
