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-   -   Engine Seize... What actually happens inside? (https://www.team-bhp.com/forum/technical-stuff/45790-engine-seize-what-actually-happens-inside.html)

We are lot hearing about engine seize in cars. In simple terms we can say that engine stops working due to some external or internal cause. But this would not give detailed explanation about engine seize.

I started this thread after reading so many complaints of Honda, Skoda etc owners about engine failure in their car due driving in heavy rain/flash floods or so.

Why many time service stations simply changes the engine and do not try to repair the same? Is that engine gone beyond repair? What actually happens inside?

For older engines, like Amby, Jeep etc mechanics simply overhaul the engine and it starts working whenever it seizes.

Experts please throw some light of this.

Is there a possibility that they are replacing over hauled engines to save on turn around time?

As far as I know, when water enters the engine, the pistons and crank rods will break. This is because water is not compressible unlike fuel and thus when the compression stroke happens with water inside, the load bearing parts simply give way.

That and the water removing the oil film will pretty much gut the insides of the engine in a few rotations (which happens in fractions of seconds thanks to people 'racing' the engine to keep water out of the exhaust).

As far as I remember engine seizure has got more to do with over heating and non-lubrication than water entering engine.

Yes, it can be one reason. But why new generation engine is simple unrepairable? That is my question and what actually permanent damages happen inside?

When engine operates, the pistons move up and down. There is very thin gap between pistons and inside wall. Oil fills up this space and acts as lubricant.

If oil runs out (for whatever reason) then pistons just stuck inside the engine and no longer moves. This is usually known as seizure of the engine.

That's why it is so important to check engine oil often.

In India, seized engine is repairable. However, in most developed countries, cost of labor is so high that if engine seizes it is considered irreparable.

In my opinion driving through rather diving in water leads to what we call as "Hydrostatic lock". In this situation water enters in the space between piston and the cylinder and since fluids are uncompressible in nature, the piston while trying to compress water either leads to bent con rods, sheared cylinder heads, blown crank cases or even bent broken crank shafts. Depending on the damage magnitude it is decided whether orgional block and cylinder head will work or not. If its a crack, blown case engine needs to be replaced, if only con rod has bent then you can do away with only sets of new con rod, pistons and bearings but ofcourse crank shaft conditions and cylinder head and crank case planes need to be checked for perfect alignment before repairing.
In typical Seizure or Cessare, the cooling system of the engine fails or underperforms and the rings on pistons melts and get glued to walls of cylinder sleeve, hampering to and fro motion and finally stopping the engine.

Yup, this is the best answer so far. In addition to the effects of Hydro Lock that is mentioned above, you can also bend valves, stretch head studs, blow head gaskets, etc.. When water enters the combustion chamber it normally results with catastrophic engine failure(and that isn't only with "new generation" motors, it is with ALL motors).

Other engine seizing is due to oil starvation and having the bearings "spin". Which means either the main bearings or rod bearings lose the oil lubrication it needs for whatever reason and the bearing literally "spins" instead of staying in place and doing their job. This results in damage to the crank journals, as well as the main caps, and the rod ends. Some can be fixed, some cannot. A lot of the times in extreme situations(modded cars), the rods will actually fuse to the crank then "fling" the pistons out the side of the block.. catastrophic damage.

And yet another form of seizing can occur from overheating of the motor in one way or another and the pistons will actually expand to a point where they actually rub on the cylinder walls and literally "seize". What happens is the oil layer is either squeezed out or burnt off in a sense(due to the piston being oversized from the heat expansion),and the clearance that is needed is lost. When the piston rubs against the walls it creates more heat and in the end, the pistons and the cylinder walls end up fusing or deconstructing each other.

So, I recently, unfortunately, got water in my engine, and indeed, a bent rod resulted. If this were to ever happen again to myself or anyone else, what is the correct method of attack? What can one do? Is there anything you can do?
Thanks :uncontrol

:eek:
In that case why the heck are you laughing??

Poor chap is in deep shock, hence doesn't know what he is doing..

They are repairable. Incase due to the seizure the cylinder walls are scratched or have deep cuts due to absense of lubrication, the block will have to be bored (make the walls uniform) which results in a slightly larger compression area. This in turn requires that we use a larger piston to make up for the larger cylinder.

a) What you referring to is hydrostatic lock, its like putting a small grenade inside the engine. Parts are bent and scarred, so in a modern engine to get the absolute tolerances back, its always advisable to take the replacement in part or completely is advised.

Also newer cars have lower stance which are prone to older amby and fiat which has the filter sitting on top and that too high. Moreover chances are electrical will conk off fast that the car cannot be started when flooded :) Funny theory eh.

Absolutely, where there is a will and means to pay the bill it can be. Though parts can be expensive and laborious process that its better to opt for replacement.

Usual culprits, cylinders, pistons, bearings, oil seals and valves are the first to go kaput in case of flooding. (not necessarily in that order)

Yes but if the job is not done by competent people following good tolerance levels, it will give more headache in the longer run.

Nice explanation Jaggu. I was thinking why these car manufacturers are willing to spend much more (by replacing engine) than just trying to repair it. Neither, car company (if it is in warranty) or insurance company objects.

As I remember, our older Amby had engine seizure due to flood and it came back home well within a week after engine overhaul and in complete working condition.

So, newer generation engine we can think off a complete unit rather than assembled with many parts.

:uncontrol

Good explanation Jaggu dada :thumbs up