Not sure if this is in the right place or not, but was thinking at work today about the piston failures, mostly from reading about the LLY and the LBZ failures but have heard there have been some Lb7 failures too, and what they are caused by. It seem s several were thought to be caused by a stuck open injector, so one of my questions is , is it dirt in the fuel that causes an injector to stick, or do they gum up? Next question would a additional in line filter help, and would would an additive help it is from the injector gumming up?
LB7,LLY, LBZ piston failure question.
- Thread starter redneckbuckeye
- Start date
the pistion faliure in my lly i think was a mixture of both studs and larger turbo. i cracked 3 they were 4,6,7. im thinking that the pressure in the cylinder what caused it. i blew a head gasket first then i studded the heads and the pressure has to go down instead of up. all my injectors were checked and they were fine.
im still not sure what caused mine, i was runnin a DD tune comin home from work when 1,3 let go, i had some weird inj balance readings on #3 but they said my injectors were fine but ever since i got my truck back it blows smoke with a stock tune in it, were it didnt before, and on top of that every tune i run i have to decrease pulse width so it dosent smoke a lot and to control my EGTs.
I was reading about a stock truck that let one go and it was said to be from a stuck open injector,in codyn's failure it would have been cheaper and easier to fix a head gasket.What kind of data is available on forged piston in a DD truck. It seems I read somewhere someone doubted the longevity of them in a DD. I sure wish we could get to the root of the cause with out a doubt I am nervous turning my truck up any higher, as I don't have money for a rebuild.
forged pistions are fine in dd i have 10000 miles on mine no problem. they have ran forged in cummins on the road so i see no problem in running them.
cheeper to fix a head gasket in my deal. i dont know because the heads were off might as well put them in while they were off. but i know one thing a forged pistion wont crack verses the cast pistion.
cheeper to fix a head gasket in my deal. i dont know because the heads were off might as well put them in while they were off. but i know one thing a forged pistion wont crack verses the cast pistion.
So are studs not a good idea, Cheaper to fix a head gasket than to fix piston failures
cheeper to leave it stock than beef them up. but you play you can pay
I cracked #1 on a hot tune stock turbo ... no studs .
I wasnt running it as hard as I usually do when it broke . I was on my hot+2 PPE with 2 cp3's . I had been really hard on it all season at the dunes running it way into 2000 deg temps . Not sure if it stuck an injector or just cylinder pressure to much . Either way it cracked a piston . On the billet pistons vs. stock . Ive heard you can run them , but not recommended for daily driver and heavy towing like I do . Basically you lose the oiling passage in piston top when you go billet . I just got my short block done and I used stock lly pistons with the lip on the bowl cut off by Guy Tripp at SoCal diesel . I used lbz rods from mcrat . Polished crank and balanced assembly . Should be back up soon . Also adding head studs and the cheetah turbo to the mix . I left the top of the piston alone and only cut lip to retain as much compression as possible .
Overall cylinder pressure is the cause of cracked pistons and heat cycling the pistons with high EGT's . Stuck injectors also can be critical , but no way to know really . I could have stuck one . Doesnt really matter , it broke .
All part of racing and having fun . The rest of my pistons looked good , even the cracked one looked good except for the crack and hole . No erosion at the lip like I would have expected .
Johnny
I wasnt running it as hard as I usually do when it broke . I was on my hot+2 PPE with 2 cp3's . I had been really hard on it all season at the dunes running it way into 2000 deg temps . Not sure if it stuck an injector or just cylinder pressure to much . Either way it cracked a piston . On the billet pistons vs. stock . Ive heard you can run them , but not recommended for daily driver and heavy towing like I do . Basically you lose the oiling passage in piston top when you go billet . I just got my short block done and I used stock lly pistons with the lip on the bowl cut off by Guy Tripp at SoCal diesel . I used lbz rods from mcrat . Polished crank and balanced assembly . Should be back up soon . Also adding head studs and the cheetah turbo to the mix . I left the top of the piston alone and only cut lip to retain as much compression as possible .
Overall cylinder pressure is the cause of cracked pistons and heat cycling the pistons with high EGT's . Stuck injectors also can be critical , but no way to know really . I could have stuck one . Doesnt really matter , it broke .
All part of racing and having fun . The rest of my pistons looked good , even the cracked one looked good except for the crack and hole . No erosion at the lip like I would have expected .
Johnny
The cylinder pressures inside an overheated piston cylinder get enormous. Advanced timing adds to the problem, with negative torque excess that sends CP north. Anyone who tows heavy, needs to add timing retard (with IAT and ECT) to the tune. This will also enhance power during these transient thermal conditions, reducing negative torque.
Applicable Article from days past
Applicable Article from days past
couple i have heard including me when the pistions let go we were not running them hard at the time. i was going up a hill going about 55 and the pistion let loose. i would kind of figure it would go when it was getting the tar ran out of it but it didn't
sometimes yes it did when mine let go. it depends how far you drive after it happens to
Mine left a huge gash in the cylinder . Still have that block . Got another block to use for now . That was the real bummer about it all .
Johnny
Johnny
Mine let go but i actually burnt a hole in the piston,I was running it hard at the time and sitting around 2000f I drove 150 miles with 7 pistons and the block was fine.....But mine wasnt cracked just holy
Mine let go but i actually burnt a hole in the piston,I was running it hard at the time and sitting around 2000f I drove 150 miles with 7 pistons and the block was fine.....But mine wasnt cracked just holy
pistion 4 had a hole burned in it the rest other 2 were cracked half wa though. sounds like it was a better deal than mine was
Mine let go but i actually burnt a hole in the piston,I was running it hard at the time and sitting around 2000f I drove 150 miles with 7 pistons and the block was fine.....But mine wasnt cracked just holy
thats how mine was, burnt but not cracked, the thing is on my way home the night it happened i only got into one time and i think it hit about 1700* right when i backed off and the rest of the time never went past 1200*
Wow
Id wrapped my 2000f gauge many many times before mine had enoughI remeber thinking before that happened that 1600f was childs play
now i will never go over that
Codyn, What brand of forged pistons are you running, if you don't mind? How is oil consumption, and winter startups with forged pistons? Thanks.