Help: lbz cracked piston?

[dwax]

under a full throttle run my truck suddenly lost all power and started pouring white smoke, (threw cyl #4 misfire) so i pulled over, shut it down and checked all fluids but all was normal, no water or fuel in the oil. Cranked it back up and the engine was running really rough and stil pouring white smoke. the smoke smells like burnt oil.. I checked my inj. rates and #4 was at 11.9 with all the rest being around -4 to 2. I put a new injector in #4 and it runs exactly the same. does this sound like a cracked piston? It gave me no prior symptoms! Oh ya, and i have bad crankcase BLOWBY!

 

[Kat]

Sounds that way

 

[wdino73]

Sorry to say but I would say yes, I just went thru this with mine, pull the number 4 glow plug an the injector fuse then have someone crank it over if it's a cracked piston thier will be no compression, u can test it with your finger, Good Luck

 

[Builtlngbd]

yep thats what mine did. sorry to here that man

 

[duratothemax]

cracked piston, without a doubt.

 

[giterdirty06]

Yeah man that's exactly what mine did as well. Except when my piston went it shot the dipstick out and oil went everywhere.

 

[duratothemax]

when I cracked a couple pistons on my LLY it blew the oil cap off and put a dent in my hood.

 

[dwax]

thanks for the replies. i was hoping not but it looks like its time for a build. EXPENSIVE!!!

 

[jonathancasey19]

Would it be possible to have a minor cracked piston and only show these symptoms under throttle?

 

[duratothemax]

Would it be possible to have a minor cracked piston and only show these symptoms under throttle?

IMO, no...even a pinhole at idle will cause big problems.

Just my opinion though.

 

[emiller3]

I did the same thing the first time with changing two injectors and ended up with some burnt pistons sad to say.good luck with it buddy.

 

[jonathancasey19]

cool thanks ben

 

[TrentNell]

Sorry to hear man good luck with the build though :hug:

 

[rcr1978]

how big of tune was used?

 

[hondarider552]

And how many miles?

 

[JD4440]

There is a thread on here somewhere it would be a good idea to post in that list all the specifics at the time of the failure. I believe Trentnell started it IIRC

 

[dwax]

it has 50000 miles with 20000 being hard miles and the first 30k being completely stock!(even tuning). it was my race tune which runs about 12.90. i dont understand this, i guess it was a freak accident! Can anyone reccomend a good piston to go with my mpi twins that are on the way?

 

[whitetrash21]

lb7 cut (and coated, if you so feel inclined) pistons are the popular choice for rebuilds.

 

[dwax]

thanks. thats what i was just figuring from my research, might as well do it right!

 

[dwax]

i already had the twins on the way, and i was plannin on leaving my engine alone!