Your opinions on 2012 engine failure

If there was “lots of oil running under the car” after the engine failure, why do you think it was run out of oil?

Separately, what do you know about the provenance and maintenance history on the donor engine?

 

When a rod breaks, the engine would knock immediately.

So this actually sounds like two events:

1) Something happened that made a loud pop and created a lot of smoke......then 20 seconds later
2) The rod broke and the engine began to knock

Oil creates smoke that's bluish, not just white. Pure white smoke probably coolant. Maybe big coolant leak into engine (head gasket failure?) overwhelmed one cylinder (since liquid not compressible) and then that rod failed?

 

common get 3 head gasket failure caused by a clogged egr circuit

have you joined the class action lawsuit?

 

If a cylinder hydraulic locks, the associated connecting rod will instantly become light-seeking.

 

There is a class action suit? I had no idea. Where can I find this? I've had my 2013 Prius V for over 2 years. I haven't had issues...yet. But I'd like to be head of the ball game if there is a class action suit.

 

Here's what I think happened.
You may have had coolant flowing into the combustion chamber, during engine strokes. Since coolant can't be compressed in the chamber, it would act as a hammer, pounding the piston heads. Remember, these pistons have certain pressure thresholds they should bear during combustion strokes. So if the resultant pressure spikes from the coolant in the combustion chamber is more than necessary, the next component to bear the brunt is the connecting rod, as you saw it rip through the engine block.

Another prove to tell you the cause of tgr failure was coolant induced, would be the white steam you saw.

The oil you saw was just an aftermath of the incident.

I'd advised that you investigate the root cause of the problem. Make sure your cooling system isn't problematic. If not, same fate may befall any replaced engine.

 

I'm willing to say, and admit you should just put my opinion lower on the totem pole.
I sense you are seeking a clear consensus winner that clearly defines the connecting rod to some direct failure that would be assignable to an outside entity.

My opinion is, if the question is, " What caused the connecting rod to be thrown through the engine block? " .

There is no direct answer. No clear cut knowable cause and effect.
Most likely?

Which would put in in the range where one IMO could say any amount of possible catastrophic engine damage could occur at any given moment.
It sounds like maintenance was maintained and was happening. It sounds like warning symptoms of upcoming failure did not appear.

There's just a lot of things you can't see on an engine, from the outside. A lot of things a mechanic changing your Oil, fluids and spark plugs can't know just by doing those things.

Once the failure happened, you had a big hole in your engine. At that point leaking oil is inevitable. But really if you witnessed no leaks before hand? I wouldn't speculate that you were low on oil, leaking oil, and anything like that possibly caused the failure.
I think it possible, you simply had a connecting rod whose time had come. Maybe rare, maybe odd, BUT...really reverse engineering what caused this disaster is pretty difficult.

I also have to say I don't know if I can agree with this statement:

We would like that type of faultless perfection from those that maintain our vehicles, but again I think you can impeccably maintain a vehicle, having all the proper things done, and still at some point metal fatigues and failures are possible, and in some cases you can't blame those doing all maintenance for NOT seeing it coming. These are machines, they can go from working perfectly...to broken in the split second turn of a gear, firing of a piston, or short circuit of a wire.

The reason I say, put my OPINION lower on the totem pole. Is I respect that many of my fellow Prius Chat posters are more learned mechanics than I am. They may have better specific tangible ideas as to cause.

But my speculation is.....maybe this seemingly out of nowhere failure, was just going to happen. Be it failure of the connecting rod itself, or failure of any of the supporting systems.

I do agree that if you replace the engine, you want to make sure peripheral systems aren't failing.
About the worst thing that could compound this situation would be investment into replacement of the engine, only to have it damaged unknowingly all over again.

 

it's on a recent thread here somewhere.

 

The engine block damage suggests that the wrist pin end of the connecting rod or the piston boss probably broke. Maximum stress on a connecting rod/piston occurs at the end of the exhaust stroke. On the compression stroke, the compressed gas on the top of the piston assists in decellerating the piston at the top of the stroke. On the exhaust stroke there is no such assistance.

The rod is trying to slow down the piston and the piston boss or rod breaks and the detached piston slams into the underside of the head, possibly fragmenting the piston. The free end of the rod is flying around battering the cylinder and underside of the piston if the piston has not already fragmented until the rod breaks and then the shorter rod can get out of the cylinder and punches a hole in the block.

On the next cycle and assuming that the valves are still operating, when the exhaust valve opens and without a piston or a partial piston in that bore, it pressurizes the crankcase with exhaust gasses from the working cylinders. It blows oil out of the hole in the block leaving a smoke trail behind the vehicle. When the intake valve opens, it draws oil mist from the crankcase into the working cylinders producing the oil smoke from the exhaust.

Why did it fail? 1. Possible casting flaw in the piston or top end of the rod that propagated over time.

Just my theory.

 

"On the compression stroke, the compressed gas on the top of the piston assists in decellerating the piston at the top of the stroke."

True, as long as it's intake mixture (compressible gas) on top of the piston.

OTOH, if the bore has filled with incompressible coolant, the hydraulic lock that occurs easily fractures the piston boss, leaving the connecting rod free to flail.

 

I like the sound of that!

 

I believe that this failure was at freeway speed. An engine that is running at freeway speeds probably can't ingest enough liquid from a blown head gasket to fail from hydraulic lock. The combustion chamber is around 35 cc's and the head gasket is 1.2 mm thick so the combustion chamber could accommodate a fair amount of coolant. Coolant from a head gasket leak would be exhausted on every exhaust cycle producing lots of white smoke.

If the engine had a blown head gasket and had just been shut down then pressure in the cooling system would fill the cylinder and hydraulic lock on start-up would be very likely.

 

Agreed, but the head gasket failure mode most often reported has not been from typical leakage but from instant, catastrophic failure of factory defective gasket material -- a 'blow out' of the near-cylinder gasket wall.

That would manifest as instant leak-down of liquid coolant into the cylinder, forced by rapid expansion and boiling of the coolant in the pressurized system, which makes it unlikely it would be forced back by the advancing piston, and very likely the piston would hydraulic lock.

Just my two cents added to yours. So we've got nearly a collective nickel into this diagnosis.

 

Agreed

 

To the OP, one of your pistons likely looks like the attached picture. I had a similar hole in the block of my 2010, and this was my number one piston. 213,649 miles. Engine startup commanded with cylinder full of antifreeze. The wrist pin exited the block at the extreme bottom edge of the cylinder wall and disappeared.