Gudgeon Pin Failure After 7500 KMS

Was there ever a period of insufficient oil pressure or flow, or possible contamination in the oil?

Odd it would happen in only one cylinder.

OP, more information on overall condition of engine, please.

One cylinder? All?

What other damage?

yes. only one cylinder

pls.

Unlikely. The car under warranty and hence oil etc looked after by the dealer. Chances of low oil pressure very low.

There are many reasons for these parts to fail. If the vehicle was operated without an air filter, or for some reason the engine ingested sand, or dirt, it will score the pistons, rings, and cylinder walls very early.

If the engine was operated for prolonged periods of time with pre-ignition, the extreme heat will erode away the tops of the pistons. Severe overheating can also contribute to this.

In my opinion, low oil quality, quantity, or pressure would be more likely to damage rod or main bearings.

From that last picture, it looks like the piston pin was driven up into the piston. Also, the bottom ring damage. Is it possible the engine hydraulic'ed? What does the connecting rod look like? How about a picture of the piston crown? What kind of engine and what application/service?

Yeah, I was coming to that delusion, too.

Hi AJ,

Looks to me like something got stuck between the piston and the cylinder wall. When I look at the piston, perhaps part of the Seeger ring broke loose and came as a wedge between the lower part of the piston (under the pin hole)and tried to lock the piston. This explains to me why the piston got decapitated from the pin hole on.

If there is no Seeger ring, it might be a part that has been thrown upwards, with the oil with the same effect. The piston has also a bad number on it. I read 13. Did it happen on Friday?

Sorry, that was the devil in me, but I really feel with you.

Do you have also pictures of the cylinder wall?

to me looks like something jammed from below as top of piston is relatively undamaged and sidewall of piston damage is below the pin- - maybe bearing cap came loose and jammed on crank forcing piston up and breaking

Looks like an overheating problem.....Have you modified the block? Coolant system? Water pump? Turbo? Intercooler size?

It is likely that a high-load event, such as a partial or full hydraulic lock, initiated the crack in the pin.. In the combustion chamber, AIR is compressed (air is a gas and therefore compressible) and then the MIST of fuel is added and then the spark to cause the explosion. If there is a lot of Fuel (a liquid and not compressible) in the combustion chamber this will cause the liquid to act a stopper, causing damage to the engine cylinder head. This is more common in off road vehicles sucking in water through the air intake.....

Note that you have a spiral break in the pin, which suggests the pin was twisted. This initiated a longitudinal crack in the pin, which travelled along a weak line. So the pin must have seized in the piston at one end, the pin was locked in the little-end, et voila.The question remains, why did the pin seize? I am suggesting an incorrect boring of the piston OR inadequate lube, so blockage of a crankshaft oilway or conrod oilway is possible. The failure of the bottom piston ring reinforces this conclusion. Someone suggested the big-end bearing was possibly incorrectly inserted, hard to do as there is probably a locating lug on the bearing slipper. This then suggests the big-end bearing was tight, seized, and filled an oilway with bearing metal, or the slipper rotated OR rubbish travelled into an oilway. More photos needed.

He said it happened under warranty and presumably it was fixed under warranty. So that, and the fact that it only happened in one cylinder, rules out dusting, sand injestion, modifications etc. etc and points to an assembly fault or the failure of a part. Cotton waste in the conrod oil gallery maybe?

It could have been the result of a simple manufacturing defect and nothing else.

I have seen and heard of it happening many times.

I'm just like others here, I'd like to see more.

in your rod- pin- piston assembly the pin is usually the hardest and most durable of the group.someone mentioned the possibility of a hydraulic condition, that usually leads to bending of the rod and cracking of the piston at the pin bore. the 1st thing I noticed was the oil control ring is only partially intact, It might have been destroyed and drawn into the pin bore...damaging the pin and bore. did you assemble the engine yourself or was it done by a trusted and trained assembler?

The engine assembled by one of the best you get.

How was the car driven during the 7500kms?

That looks like a piston for a diesel engine.

Someone put gas in the tank instead of diesel?

You don't show the crown of the piston so I assume nothing struck it like a nut or bolt dropped down the intake system.

The wrist pin looks like it might have been the first in a string of failures. Note the crack along the length which suggests the pin was not machined from solid metal but perhaps rolled or forged from a flat piece of metal.

I don't think this was caused by lubrication failure. Either the wrong fuel, bad part or an impact with something on the top of the piston

Dropped valve.

I notice the bottom half of the skirt is missing and a piece of the pin still in the remaining part. Possibly if the piston was defective and broke away it would create a side load on the pin leading to the failure. I would suspect very high rpms could contribute to the failure, but new vehicles normally protect against over speed - unless that was defeated for racing.

There are so many things that could cause this, but assuming the parts used correctly, correct type, well lubricated at PROPER Assembly, I would guess that possibly a big end shell was wrongly orientated or badly drilled, blocking the oil flow to the gudgeon pin (though I would have expected an earlier failure than 7500KM).

Or the oil way was simply not cleaned properly and was at least partially blocked in that con rod/Piston assembly.

I feel that the problem was a catastrophic failure of the gudgeon pin/piston bearing. The rest of the piston above the gudgeon pin is intact, eg. it does not appear to be a hydraulic failure as usually all cylinders would be affected.

It would have been useful to see pictures of the sides of the piston at 90° to the gudgeon pin. That might show excessive wear from a seized pin/small end/piston.

Some engines have the gudgeon pin held firmly in the small end and locked with a bolt (what I think that was the case here, but just guessing!) and the pin oscillates in the piston, some have a floating pin held with clips or some other method.

Could have been as I said before, wrong assembly, wrong parts, badly made parts (missing an oil hole for example, blocked oil way, dirty assembly, possibly wrong oil....

If it's still under warranty, as discussed above, then it's the dealer's problem to rectify, and any attempt at investigation here is merely academic.

hi
The last picturer shows the location for the pin, it looks like there is a spring clip, wire retainging clip in place.

I had simular damage on a pistion when the clip came loose snarled up the workings.

This may explain why theres just damage to one piston, not all of them, no sign or oher mechincal damage.

It looks like the engine is not balanced. either temperature based or pressure based in (other words engine is not properly tuned) that's why one cylinder piston damaged if the engine is not balanced diff in bump clearence may reduce in cylinder and increase in some other cylinder and when acceleration it will be knocked down gudgeon pin fails due to ecessive load createdby imbalance cyclinder.root cause of failure is engine unbalance.every 5000 kms engine needs to checked for balancing means all the cyclinders takes uniform load

You have not mentioned the make of car is it "Nano"?

Ankush,

As has been mentioned you most likely just got screwed by your chinese neighbor.

The fix is likewise simple, replace the entire engine with one of known parts sourcing.

Sorry about your luck, we've been screwed by those same folks too. Damned expensive lesson to learn the hard way.

1- It is a fatigue crack due to the complex loading of this kind of pin: the sections between connecting rod bearing and piston are loaded in shear+bending + ovalisation.

2- Picture up right shows a fracture which started on the internal surface and progressed to the exterior till a catastrophic failure occurred.

3- Picture down right shows a longitudinal crack in the region where stresses on the internal surface are "tension" due to the way load is transferred between piston and connecting rod

4- Picture down left shows that above mentioned crack progressed from internal diameter to outside till it came to a catastrophic failue

Both show a behavior according to fracture mechanics theory: progressive crack increase till catastrophic failure.

The pin was made from a steel with a too low fatigue limit. It is a manufacturing problem. Look at the origin of this part since if replacement made with similar parts same results should be expected.