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Driving down the road this summer and my wife's 04 Avalanche nosed over and started pouring white smoke. Naturally I assumed it was s head gasket. Well I just finally got around to opening it up, and this is what I find. Cylinder wall has like a 4" crack in it. It appears, that at the bottom ish there is even a small hole and it looks like the sleeve is paper thin. This thing is stock as stock can be, 120k. Blows my mind, guess I got the one in a million block.
Yea I've bored plenty of them to 3.89 and even some aluminum ones to 3.908, this is crazy. Here is the rest of the aftermath. In starting to wonder if the previous owner didn't freeze it. The piston ring lands and rings are all intact and in good shape, I'm leaning more towards the cylinder wall doing this to the piston, than the piston cracking the cylinder wall. Crank has been turned .010 and has std bore speed pro Pistons
Okay, so engine had been apart before. I was assuming it was never touched when you said “stock as stock can be”.
With the skirts broke off that piston, you had quite a noise on your hands.
I would lean toward the block freezing up, by the way the material at the crack looks like it was torn, or pushed inward of the cylinder.
Coolant passages in the block show signs of rust? Would be an indicator of someone running straight water.
That block should not have graphite head gaskets... They should have been MLS.
Someone has definitely been inside of it with the crank being turned .010 under and the speed pro part number on the top of the piston. I wonder if the block was rusty in the cooling system as in the ran it with straight water.
Where the head bolts all the same length???
What's the number and letters on the front of the right front of the block above the water pump hole???
That block should not have graphite head gaskets... They should have been MLS.
Someone has definitely been inside of it with the crank being turned .010 under and the speed pro part number on the top of the piston. I wonder if the block was rusty in the cooling system as in the ran it with straight water.
Where the head bolts all the same length???
What's the number and letters on the front of the right front of the block above the water pump hole???
it's a 3 length block, agreed it should have been mls. Not sure on the numbers I'll have to look
Originally Posted by MY_2K_Z
That motor is nasty on every level
agreed, this truck ha been a joke since the day I bought it. In 6 months. New trans, tcase, Ac pump, wheel bearing, , break lines, etc etc etc. I bought it because it was low ish miles at 120k.... I think someone must have swapped clusters, shouldn't be this bad with that low of miles.
No sense wasting any time trying to figure out what some yutz graunched into it. Not least because, probably no sense went into it in the first place.
Into the trash. Start over. Pick one up at the junkyard. No way you can fix that POS for ANYWHERE CLOSE TO the cost of a perfectly good used one which if all it is, is a DD for your SO, is all it would have had if it came to you PERFECT except with 120k on it, instead of ... that. Maybe put a fresh set of crack-repaired heads on the junk one, if you can't get one with something other than the Castech nightmare.
No sense wasting any time trying to figure out what some yutz graunched into it. Not least because, probably no sense went into it in the first place.
Into the trash. Start over. Pick one up at the junkyard. No way you can fix that POS for ANYWHERE CLOSE TO the cost of a perfectly good used one which if all it is, is a DD for your SO, is all it would have had if it came to you PERFECT except with 120k on it, instead of ... that. Maybe put a fresh set of crack-repaired heads on the junk one, if you can't get one with something other than the Castech nightmare.
fixing it was never the plan after the crack was founded, I'm saving the gen 4 rods and throwing the rest away. I've got l33's, lc9's, gen 4 irons etc, but I didn't want to waste any of my good motors. I bought wrecked 04 taboe for $400, yanked the motor yesterday, just going to drop it in and go. I was just curious if anyone had seen one crack like this
Can't say I've ever seen a failure like that; where it was that thin, from the water jacket side. That doesn't even look like a "crack", as such. That's ... special. And not in a good way.
I ran into the same thing last year in an 08 5.3. Iron block cracked on cylinder 5, but we all thought it was a head gasket at first. Compression check showed #5 was low so I tore it down only to find a good looking head gasket. Looking hard enough I found it.
01-30-2018, 12:48 AM
Anyone seen a stock 5.3 crack a cylinder before? 
