Pulling head/s

[Chevy1925]

Cross hatch is still there and you can feel it, Pistons looks brand new other than they all are started by to crack at the top, some in multiple places, #8 has small cracks on the lip in between the injector marks in three places, and it’s got a 32nd of a wide crack, with that and #2 cracked that’s where my oil in the driver side PCV was coming from.

I’m not doing anything glorious, stock lb7 slugs, new bearings, new head bolts and gaskets and back together it goes.

looking at it wont tell you anything, you would be surprised at the wear from new to used.

Anyhow, thats me being a stickler when putting an engine together. if i were in your shoes, id do the same but id SERIOUSLY delip those pistons. just take them to a machine shop, tell them to take 1/8" off the lip, round it out and give them back to you. shouldnt take them more than a day to do. it will really help with your right foot. add in some new rings too

 

[PureHybrid]

Open up to 2.5" on the bowl with a 3/8 radius IIRC

 

[WVRigrat05]

Joe’s gonna post of pics of the pistons so you can see how they’re cracked.

 

[lutzjk913]

Here they are man

<a href="http://s1053.photobucket.com/user/lutzjk9131/media/475D06E0-AAF7-4BDF-A89C-E577A2A6CABB_zpsyfddua2c.jpg.html" target="_blank"><img src="http://i1053.photobucket.com/albums/s469/lutzjk9131/475D06E0-AAF7-4BDF-A89C-E577A2A6CABB_zpsyfddua2c.jpg" border="0" alt=" photo 475D06E0-AAF7-4BDF-A89C-E577A2A6CABB_zpsyfddua2c.jpg"></a>

<a href="http://s1053.photobucket.com/user/lutzjk9131/media/E2FDD531-9AA8-4C17-AE3F-6BF04BA2794E_zps1g9x8izl.jpg.html" target="_blank"><img src="http://i1053.photobucket.com/albums/s469/lutzjk9131/E2FDD531-9AA8-4C17-AE3F-6BF04BA2794E_zps1g9x8izl.jpg" border="0" alt=" photo E2FDD531-9AA8-4C17-AE3F-6BF04BA2794E_zps1g9x8izl.jpg"></a>



<a href="http://s1053.photobucket.com/user/lutzjk9131/media/D5AA4C2E-5456-4081-802C-D7B7BF99AB6A_zpslc9atg7q.jpg.html" target="_blank"><img src="http://i1053.photobucket.com/albums/s469/lutzjk9131/D5AA4C2E-5456-4081-802C-D7B7BF99AB6A_zpslc9atg7q.jpg" border="0" alt=" photo D5AA4C2E-5456-4081-802C-D7B7BF99AB6A_zpslc9atg7q.jpg"></a>

 

[Robby Avery]

That's only four I thought all 8 were toast? Is that the only one cracked all the way across or were there more? Rest look like hair line fractures

 

[WVRigrat05]

That's only four I thought all 8 were toast? Is that the only one cracked all the way across or were there more? Rest look like hair line fractures

I only took pics of the driver side, passenger side is just hairlines on the top just like the ones in the pic, only one was completely split, just never seen pistons start to crack on the tops like that was the reason for the pics.

 

[Chevy1925]

That’s not uncommon. This is what happens when the lip gets super heated from high duration, high timing tuning. One of the pistons from my engine was the same way. I still have it if you want a pic lol. Anthony has pics of his race cast Mahles that all 8 cracked on him too, I just don’t remember if he was running stock injectors back then too or not.

Now take the damn lip off the lb7/lly pistons!

 

[WVRigrat05]

That’s not uncommon. This is what happens when the lip gets super heated from high duration, high timing tuning. One of the pistons from my engine was the same way. I still have it if you want a pic lol. Anthony has pics of his race cast Mahles that all 8 cracked on him too, I just don’t remember if he was running stock injectors back then too or not.

Now take the damn lip off the lb7/lly pistons!

Didn’t know that James, my LLY had 6 with cracks in it and they were all on the sides and one had a nice hole, I looked online and couldn’t find any cracked like mine, figured timing did it, just didn’t imagine there’d be multiple ones on this truck, I really was surprised.

 

[Robby Avery]

That’s not uncommon. This is what happens when the lip gets super heated from high duration, high timing tuning. One of the pistons from my engine was the same way. I still have it if you want a pic lol. Anthony has pics of his race cast Mahles that all 8 cracked on him too, I just don’t remember if he was running stock injectors back then too or not.

Now take the damn lip off the lb7/lly pistons!

Similar to running tuning on kill all the time and a heavy foot helping

 

[WVRigrat05]

Similar to running tuning on kill all the time and a heavy foot helping

I ran my 120 tune 98% of the time, but the truck weighed 9k and I have a 100 pound foot.

 

[Chevy1925]

Those cracks were what I was looking for when I pulled my heads a couple years ago. It’s how blown pistons start and then when under wot, when one lets loose, it blow torches through and hurts the block

What’s kind of interesting is the fact every crack is headed perpendicular to the wrist pin but the one that cracked all the way is over the wrist pin like so many others do.

 

[WVRigrat05]

Those cracks were what I was looking for when I pulled my heads a couple years ago. It’s how blown pistons start and then when under wot, when one lets loose, it blow torches through and hurts the block

What’s kind of interesting is the fact every crack is headed perpendicular to the wrist pin but the one that cracked all the way is over the wrist pin like so many others do.

See how #8 has cracks at 12, 3, and 5 o’clock? Weird.

I figured the other 7 would be perfect and the block would be junk, I drove it around 7 miles and left it idle while I waited on my ride because it was hot out.

Mine let go at 1600 rpms, the LLY let go at 4500 rpms and it scratched the block up but was reusable.

 

[PureHybrid]

I'd venture to say high sustained EGTs started the small cracks, plain old high cylinder pressure started the big parallel crack.

 

[NC-smokinlmm]

Remember when you got stuck in the creek and blew your dipstick out? I'd be willing that or the road rage incident you described once were the culprits of the split pistons. :spit:

Seriously, I've seen it before. My buddies looked just like that, big PPE tune 100% of the time and a heavy foot. Split one just like yours...

 

[lutzjk913]

Needless to say I'm a little worried now after seeing these.

 

[Robby Avery]

I ran my 120 tune 98% of the time, but the truck weighed 9k and I have a 100 pound foot.

Don't shoot the messenger but guy trip of so cal diesel said it best to me a long time ago either turn the wick down and enjoy it for a long time or run it hard shorten the life and rods and find the weak links or in this case crack the pistons. I for one wish mahle would bring the unicorn monotherms back into production for the duramax I know I know it probably will never happen. But we all can dream and maybe they will:thumb:

 

[WVRigrat05]

Don't shoot the messenger but guy trip of so cal diesel said it best to me a long time ago either turn the wick down and enjoy it for a long time or run it hard shorten the life and rods and find the weak links or in this case crack the pistons. I for one wish mahle would bring the unicorn monotherms back into production for the duramax I know I know it probably will never happen. But we all can dream and maybe they will:thumb:

I knew it was gonna happen, just not to this effect so quick, oh well I’ll have it back together soon enough, just gotta round up the parts

 

[Josh154]

I need to stay out of this thread been running a 3300uS tune for 2 years now and blown a turbo up I’ve pushed it so hard

 

[Chevy1925]

I need to stay out of this thread been running a 3300uS tune for 2 years now and blown a turbo up I’ve pushed it so hard

told ya to borescope them pistons but maybe its best left unknown so when it does go, you can have the actual surprised face for the little woman

 

[Josh154]

Hopefully it lets go when she’s driving it :roflmao: