Help: lbz cracked piston?

[wdino73]

I posted earlier in this thread what I did, if it's a cracked piston u won't need a tester, just pull the g-plug, pull the injector fuse so it won't start, have someone crank it over a few times, you'll be able to tell with your finger if u have compression or not, I had alot of blowby, an no compression,

 

[shark1]

Hey guys after reading the entire thread, it's becoming more and more clear to me you gotta pay to play and that being said, it seems that you guys are rebuilding but then replaceing with OEM pistons my question is why? Also I was always under the impression that the duramaxs had a pretty stout bottom end am i worng? or are you guys just pushing the limits as far as you can go ?

 

[duratothemax]

Hey guys after reading the entire thread, it's becoming more and more clear to me you gotta pay to play and that being said, it seems that you guys are rebuilding but then replaceing with OEM pistons my question is why? Also I was always under the impression that the duramaxs had a pretty stout bottom end am i worng? or are you guys just pushing the limits as far as you can go ?

Almost all of the pistons that are cracking are LBZ/LMM pistons. They are an inferior design compared to the LB7/LLY pistons.

Guys are pushing these motors very hard; it is mainly EGT's that get the better of pistons. We're talking running them way over twice what they were designed for....

When the LB7/LLY stock pistons are prepped correctly (de-lipped, maybe coated), they have proven to last well under high HP conditions....and are pretty cheap to buy (used). So generally when LBZ/LMM guys crack pistons they replace them with stock/delipped LB7/LLY pistons.

 

[calabria69]

i hate reading threads like this!! im almost 100,000 miles now and im crossing my fingers everyday!!

 

[hondarider552]

100k on your LMM? Holy crap!

 

[Gya0ma7ha]

Delipping them cuts down that sharp lip on the bowl right? I assume that's to cut down on the heat transfer to such a small area. I can guess that the edge of the bowl gets extremely hot.

 

[TeaBagger2006]

we need some titanium pistons ....titanium crank..... titanium rods.....and a titanium block.....

 

[Redbowties88]

we need some titanium pistons ....titanium crank..... titanium rods.....and a titanium block.....

ok let me give my formula 1 buddies a call:rofl:


actualy they still use steel cranks as per regulations....we just gotta figure out how they get them to last at 21k+ rpm

 

[TeaBagger2006]

i can only imagine how much mula that would take

 

[whitetrash21]

ok let me give my formula 1 buddies a call:rofl:


actualy they still use steel cranks as per regulations....we just gotta figure out how they get them to last at 21k+ rpm

Easy....itz called 250 ft/lb tq. Massive torque and slow speeds is a recipe for parts failure, espespecially when asking those parts to handle 3 or 4 times what they're rated for

 

[8100 Power]

i wanted to confirm a cracked started by taking the #4 glow plug out, running the engine and checking for blowby. Well it still has blowby! i guess i need a compression tester

Any update?

 

[dwax]

got a new engine out of a 3500 dually with 6 thousand miles. the new engine and twin turbo setup should be in next week! im just goin to slowly build my old engine