How is this even possible?? ( graphic pics)

AGREED..i need an ej20g as well :yumyum:

 

Well...

Normally I'd say either fuel starvation or intake manifold leak to explode one piston, but being that they're different manifolds...

Possible situations:
- Fuel starvation leading to detonation
- Intake manifold leak on one piston which exploded, and somehow a piece of it escaped into the crankcase and found its way into the opposing cylinder, destroying that piston??


No matter what happened, RIP that engine. You've got quite the boat anchor now. I wouldn't try to rescue any piece of it. Two thumbs down, dude. Condolences.

 

^^ i like can see how that would do it. Both of those pistons got disintegrated while the other two are untouched. The crank has a some gouges on it we can see. But a very curious case of exploding piston this is to me.

 

1-2-3-2 shift is my guess, and if the engine were low on oil it definitely wouldn't help any. Owie. I watched a 3000GT do this exact same thing in front of me.

 

SOHC 2.5s are very interesting engines, they can be complete piles of **** in one car, and great in another

 

Comforting... :eek4:

 

If yours is quiet, its pretty much fine.

 

My guess? I'm with piddster - CAI caused lean conditions and mega-knock shattered the pistons. Misshift may have helped.

 

I have seen it before, in my old Baja.




Yes mine also munched the opposing side too. Once the first piston breaks apart its pieces are transferred to the other side via the crank rotation, then on the next down stroke of the piston, the piston collides with those newly introduced pieces drags them down into the crank where they get wedges in between the crank and the intact piston as it tries to reach bottom dead center the weak link gives way(rod or piston).

There are a number of possibilities as for a cause. Most basic being metal fatigue(were there any contributors(det, starvation.....) who knows?). As Piddster said, Cast aluminum does not fail with grace, it tends to be a catastrophic failure vs. a gradual one.

-Stuck a piston, and it shattered. The 2.5L has a short skirt piston. Combined with any of the following you have a recipe for a shattered piston.

-Loose fitting piston, piston slap would be an indicator, not uncommon in the era of this engine, the cylinder bore has worn into a egg shape and so on.

-A engine that was not fully warmed before it was reved out. Different expansion rates for different metals. Aluminum piston expands faster then cast iron cylinder liners combined with cold oil that doesn't get tossed around very well = inadequate lubrication which promotes galling which can all snowball into a stuck/seized piston that shatters. NOTE, this happens most often in my experience with dirt bikes, ATVs, jet skis and the like. They get pulled out of storage/trailer fired up and the guys takes off at warp speed down the track/field, lake to be stopped in his tracks 50-300 yards away when it grenades.

-Wrist pin clip popping out allowing the pin to walk out into the cylinder wall and get hung up in the access hole for the wrist pin (this was my case, you could clearly see the indications on the block and wrist pin bore of the broken piston and wrist pin where every thing impacted.

-Ever popular over reved, missed shift.

In the end some one who knows what signs to look for would have to look at the parts in person. I agree with others saying there may have been a contributing factor from a intake..... promoting det further fatiguing the piston that in its self or combined with other sources lead to cookie crumbles :yumyum:

 

WOW that was fantastic write up, your enigine looks identical to how my friends engine looks. I will post pics of the block when we tear it apart

 

Mine let go leaving a stop light in traffic(3rd car in line) on 169 in Elk River, hardly beating on it.

Unlike flesh and bone metal doesn't recover once it starts to fatigue. It only gets weaker and weaker until it fails. The det theory works because as time goes on the little bit of damage from each instance of det incurred by the piston slowly takes its toll, The piston gets weaker and weaker. Even in a case where the cause of det has been remedied, it could still fail years down the road from the damage that was started then.

Or a missed shift by a previous owner could have been what started the ball rolling, leading to the piston bits now.

Oh and stay away from the Cummins reman shortblock from Subaru. The build quality was less then desirable in my experience.

 

Yours was the only instance ive ever even heard of....must have been made on a friday afternoon.

 

I wish you guys could have seen some of the cash for clunkers. This is rookie stuff :laugh::laugh::laugh:.

 

They have gotten a lot better now, because of cars like yours.

There was quite a few, his was only one of two I know about locally.

 

Looks like your trying to smuggle heroin in your engine in the first few pics.

 

There are a few horror stories on various Subaru sites by several people, maybe a dozen or so. My old man works at Cummins, he kept tabs for a few months after my incident of how many RMAs/charge back claims they recived from SOA at the OEM engine remanufacturing plant. In the immediate 30 days after the number was in the mid 60s and after 90 days the number was over 200. So I was not the only one who was unhappy. I think I just took the brunt of the battle to get the issues recognized.

Still, no one should have to force your way to the cfo/evp to get it covered.

 

I'm not arguing with you, I knew they had their problems. I'm just saying they are now a lot better. And no you should not of had to fight so hard with them, if it was our old rep, then I could see why, he was a real D bag, our current rep is a very fair guy to both costumers and dealerships.

 

I don't know that I can quite agree with the CAI causing this much of an issue. If it was running that lean, to cause serious detonation...there should have been a CEL long ago. If there was, and it was a lean code...then it's the owners own fault for letting it go, until "it went".

I could see a faulty rod bearing though. If the rod got tight, that would put lots of extra pressure onto the piston, leading to fractures and breakage. Notice the rod is tweaked a bit, which could be from sudden impact of a piston to valve or extreme force upon the skirt of a piston. That couldn't have ruled out detonation, as knock and detonation can assist in killing rod bearings.

Either way, that engine is long gone, and I wouldn't attempt to salvage any part of it.

 

Sorry about the engine, but that's some damn good carnage.

Cookie-monster approved!

 

WOO ^^ lol yeah i thought everyone would like to seem them. I'll have more when the block comes apart.

 

My response was more towards awdimprezal. So no arguing.

 

I finally graduate in May, so I see the light. Shortly before my 29th birthday, lol. The gov't been pretty good to me so I'm not too far in the hole. The car hasn't helped though.