Spark plug crushed... how bad am I screwed
May 24, 2009, 01:23 PM
#46
The popped rocker is on the side of the piston damage.
May 24, 2009, 04:55 PM
#47
It wasn't valve float.
Detonation broke the ring land.
The ring land jacked up the valve (popped off rocker) and the spark plug. Probably jacked up the turbo as well.
The thing about failures is that typically the damage is actually done at some other point in time. A heavy detonation event may start a crack in the piston but not actually cause a piece to break off. Several detonation events later (or even just normal use) and the crack that was started a while back finally propagates enough to finally cause complete failure in the piece.
It's like the guy saying his piston broke driving around at 25mph. The piston didn't crack in that situation. The crack happened before then but cyclic stress from normal use caused that crack to propagate until failure.
Further, this idea of "With a knock count of 4, I wouldn't expect this to happen" is a false sense of security. It's not like a knock count of 4 means it was mild detonation. It just means there was ENOUGH detonation events to allow the knock counter to reach 4. 1 single HARD detonation event may only show up as a knock count of 1, but it can easily cause a crack in a piston. Realize cylinder pressure under normal ignition at that kind of power is probably 1500-200 PSI. Detonation on the other hand is 5000+ PSI. The force subjected to the engine under detonation is just SO MUCH greater then under normal combustion.
Detonation broke the ring land.
The ring land jacked up the valve (popped off rocker) and the spark plug. Probably jacked up the turbo as well.
The thing about failures is that typically the damage is actually done at some other point in time. A heavy detonation event may start a crack in the piston but not actually cause a piece to break off. Several detonation events later (or even just normal use) and the crack that was started a while back finally propagates enough to finally cause complete failure in the piece.
It's like the guy saying his piston broke driving around at 25mph. The piston didn't crack in that situation. The crack happened before then but cyclic stress from normal use caused that crack to propagate until failure.
Further, this idea of "With a knock count of 4, I wouldn't expect this to happen" is a false sense of security. It's not like a knock count of 4 means it was mild detonation. It just means there was ENOUGH detonation events to allow the knock counter to reach 4. 1 single HARD detonation event may only show up as a knock count of 1, but it can easily cause a crack in a piston. Realize cylinder pressure under normal ignition at that kind of power is probably 1500-200 PSI. Detonation on the other hand is 5000+ PSI. The force subjected to the engine under detonation is just SO MUCH greater then under normal combustion.
Last edited by 03whitegsr; May 24, 2009 at 04:59 PM.
May 24, 2009, 09:36 PM
#48
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IM NEW AT THIS BUT I HAD THE SAME PROBLEM........
HAVE A EVO8 WAS DRIVING 25MPH ALL OF A SUDDEN MAD A UGLY SOUND AND THEN SOUNDED LIKE A SUBARU GO TO FIND OUT CYLINDER # 3 NO GOOD CHANGE THE SPARK CAUSE IT WAS BENT IT WAS RUNNING GOOD BUT WITH TIME IT WOULD STOP WORKING JUST TO FIND OUT THAT THE SPARK PLUG KEEPED GETTING BENT.....
TOOK THE HEAD COVER OFF THE TAB HAD FELL OF TOOK THE HEAD OFF 2 BENT VALVES THE PISTON LOOK GOOD OK GOT THE VALVES FIXED PUT THE MOTER BACK TOGETHER AND AS SOON AS I MADE THE FIRST STOP SAME PROBLEM AGAIN ....
TOOK THE HEAD BACK OFF ONLY TO FIND OUT THAT THE 2 VALVES GOT BENT AGAIN BUT THIS TIME MY PISTON WAS NO GOOD I WAS LIKE
AFTER GOING THRU LIKE 6 SPARK PLUGS THIS WAS THE PROBLEM.. WHEN THE TAB FELL OF IT CAUSED THE VALVE TO NOT FUNCTION THE RIGHT WAY CAUSING ONE OF THE VAVLES TO CHIP(VERY SMALL PEACE) THE CHIP WAS SO LITTLE IT WOULD GO IN A CURCULATION MOTION THRU THE MANIFOLD,TUBO,INTERCOOLER, INTAKE(LUCKY IT DIDNT DO ANYTHING TO THE TURBO) BACK TO THE HEAD AND DOWN TO THE PISTON THEN BEND THE SPARKPLUG ONE AFTER ANOTHER....TOOK ME 6 SPARKPLUGS TO FIND THE PROBLEM REASON TO FINDING THE PROBLEM WAS THAT THE PISTON HIT THE SPARKPLUG SO HARD WHEN THE METAL WAS IN THE CYLINDER THAT THE SPARKPLUG BLEW UP IN PEACES THANX TO THE COILPACK FOR BEING SCREWED ON... IF NOT SPARKPLUG WOULD HAVE FLEW OUT THE HOOD....THIS TIME IT HAD BROKE THE PISTON BY LOOKING AT THE TOP OF THE PISTON U CAN TELL THAT THE PISTON WAS HITTING A PEACE ON METAL WHICH THAT SAME METAL WAS CAUSING SPARKPLUG TO BEND.....
SOLUTION: NEW PISTON ONLY THING IS IM NOT A PRO..LOL FORGOT ONE BEARING ...2 WEEKS LATER MOTOR WAS NO GOOD LOL THATS WHY I LEAVE THE HARD WORK TO THE PRO'S NOW IN DAYS LOL
ANYWAYS GOT ME A FULLYBUILT MOTOR WITH AMS INTERCOOLER AND INTERCOOLER PIPEING.....SWEET..LOL
THIS WAS MY PROBLEM HOPE THIS HELPS OUT A LITTLE IF ANY QUESTIONS LET ME KNOW..GLAD TO HELP....
HAVE A EVO8 WAS DRIVING 25MPH ALL OF A SUDDEN MAD A UGLY SOUND AND THEN SOUNDED LIKE A SUBARU GO TO FIND OUT CYLINDER # 3 NO GOOD CHANGE THE SPARK CAUSE IT WAS BENT IT WAS RUNNING GOOD BUT WITH TIME IT WOULD STOP WORKING JUST TO FIND OUT THAT THE SPARK PLUG KEEPED GETTING BENT.....
TOOK THE HEAD COVER OFF THE TAB HAD FELL OF TOOK THE HEAD OFF 2 BENT VALVES THE PISTON LOOK GOOD OK GOT THE VALVES FIXED PUT THE MOTER BACK TOGETHER AND AS SOON AS I MADE THE FIRST STOP SAME PROBLEM AGAIN ....
TOOK THE HEAD BACK OFF ONLY TO FIND OUT THAT THE 2 VALVES GOT BENT AGAIN BUT THIS TIME MY PISTON WAS NO GOOD I WAS LIKE
AFTER GOING THRU LIKE 6 SPARK PLUGS THIS WAS THE PROBLEM.. WHEN THE TAB FELL OF IT CAUSED THE VALVE TO NOT FUNCTION THE RIGHT WAY CAUSING ONE OF THE VAVLES TO CHIP(VERY SMALL PEACE) THE CHIP WAS SO LITTLE IT WOULD GO IN A CURCULATION MOTION THRU THE MANIFOLD,TUBO,INTERCOOLER, INTAKE(LUCKY IT DIDNT DO ANYTHING TO THE TURBO) BACK TO THE HEAD AND DOWN TO THE PISTON THEN BEND THE SPARKPLUG ONE AFTER ANOTHER....TOOK ME 6 SPARKPLUGS TO FIND THE PROBLEM REASON TO FINDING THE PROBLEM WAS THAT THE PISTON HIT THE SPARKPLUG SO HARD WHEN THE METAL WAS IN THE CYLINDER THAT THE SPARKPLUG BLEW UP IN PEACES THANX TO THE COILPACK FOR BEING SCREWED ON... IF NOT SPARKPLUG WOULD HAVE FLEW OUT THE HOOD....THIS TIME IT HAD BROKE THE PISTON BY LOOKING AT THE TOP OF THE PISTON U CAN TELL THAT THE PISTON WAS HITTING A PEACE ON METAL WHICH THAT SAME METAL WAS CAUSING SPARKPLUG TO BEND.....
SOLUTION: NEW PISTON ONLY THING IS IM NOT A PRO..LOL FORGOT ONE BEARING ...2 WEEKS LATER MOTOR WAS NO GOOD LOL THATS WHY I LEAVE THE HARD WORK TO THE PRO'S NOW IN DAYS LOL
ANYWAYS GOT ME A FULLYBUILT MOTOR WITH AMS INTERCOOLER AND INTERCOOLER PIPEING.....SWEET..LOL
THIS WAS MY PROBLEM HOPE THIS HELPS OUT A LITTLE IF ANY QUESTIONS LET ME KNOW..GLAD TO HELP....
Good first post...just don't type with all CAPS. Punctuation helps as well.
May 25, 2009, 01:05 PM
#49
Pistons are out, head & turbo are apart. Two big pieces of piston were lodged in the hotside, they never made contact with the turbine (lucked out there). The valves were not bent, although the one with the popped rocker did chip at the rocker-end and will need to be replaced.
The head will need to be machined, there's a lot of melted material in that cylinder.
The cylinder will be ball honed, there is some scuffing opposite the piston failure. The rest of the cylinders look good, nice crosshatch.
The bearings & crank look perfect, unscathed.
The head will need to be machined, there's a lot of melted material in that cylinder.
The cylinder will be ball honed, there is some scuffing opposite the piston failure. The rest of the cylinders look good, nice crosshatch.
The bearings & crank look perfect, unscathed.
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