I'm doing a build on a lml right now with busted crank. Stock fueling, built trans, s475/stocker. Not sure on miles it had.
Broken Crankshaft Count?
- Thread starter EDP
- Start date
So I'm assuming the only true fix for the broken crank issue is reducing the width of the rod journals, correct?
That's the current approach by most aftermarket producers.
What I would like to see is someone increase diameter on the mains. Mercedes used that approach to address harmonics and twist on their latest diesels with good success.
Well sure hope this is the fix because I just bought a billet crank for my build really don't want to risk it with the stock one so I'm spending the extra cash
It's all Just luck really. I'm still running my stock crank on my lly at 250k with built motor and I'm very hard on my truck lol
summer of 2015 I fractured a crank at the merchant automotive battle of the diesels. the motor was completely stock with stock fuel and a stock/s475 compound kit and 231,000 miles. After one of my passes the motor had a slightly different knock. balance rates were within spec but when I shut off cylinder 7 the knock went away. I drove the truck another 600 miles. One day the knock noticeably got worst so I pulled the lower oil pan to find copper shavings. Pulled the motor and torn it down to find the #2 main spun. With the crank out I could see the fracture on the throw next to the #2 main. since the crank never snapped and I shut it down right after the #2 main spun, I was able to reuse the block. I still have the crank, I put a lamp shade on with some Led lights and made a lamp out of it.
November of 2015 i finished my motor build. I went with a new LML crank Ati damper billet mains with studs externally balanced 40 over fingers 16 to 1 pistons carrillo rods. 6480 af cam ported heads and put it all back together with the stock fuel system. From day 1 the motor always had a weird know to it. Some suggested the different knock was the mahle pistons had a centered wrist pin instead of being offset like factory pistons. Every oil change in the motor was lab tested and they all came back clean.
A few months later 1 added an exergy 12mm pump and drove it all last summer. in the fall I tossed in some 100 over S&S injectors and it ran great for a few months. With 14 months on the motor and already 30,000 miles It was running great until this last week. A few days ago the motor started to sound a bit louder. I though it was an exhaust leak. Then on my way home from work the motor started missing. It threw a crankshaft position sensor code and the belt was squeaking. I pulled the belt and grabbed the damper and it flops all around. Broken crank number 2. I'm scared to put anything back in it unless its a narrowed journal billet crank. I'm not the kinda guy who likes to take another shot at something I already tried to do well. It would be nice if there was a proven solution. Not complaining I just wanting to help find a solution.
November of 2015 i finished my motor build. I went with a new LML crank Ati damper billet mains with studs externally balanced 40 over fingers 16 to 1 pistons carrillo rods. 6480 af cam ported heads and put it all back together with the stock fuel system. From day 1 the motor always had a weird know to it. Some suggested the different knock was the mahle pistons had a centered wrist pin instead of being offset like factory pistons. Every oil change in the motor was lab tested and they all came back clean.
A few months later 1 added an exergy 12mm pump and drove it all last summer. in the fall I tossed in some 100 over S&S injectors and it ran great for a few months. With 14 months on the motor and already 30,000 miles It was running great until this last week. A few days ago the motor started to sound a bit louder. I though it was an exhaust leak. Then on my way home from work the motor started missing. It threw a crankshaft position sensor code and the belt was squeaking. I pulled the belt and grabbed the damper and it flops all around. Broken crank number 2. I'm scared to put anything back in it unless its a narrowed journal billet crank. I'm not the kinda guy who likes to take another shot at something I already tried to do well. It would be nice if there was a proven solution. Not complaining I just wanting to help find a solution.
Sounds like you gave it every thing you could to prevent the broke crank...
I think you already called it, Waglers narrowed journal crank.
I think you already called it, Waglers narrowed journal crank.
Like Burn Down said...get a Wagler narrowed journal crank. Once you do that everything else around it will start breaking.
I'd be a bit shy about using that same block again at this point. Might check the line bore to be safe.
It's one for sure. Lots of mods done to it so interesting to know what hp/tq it was at. A little strange with the noise right from the build-may have been something going on with it right from the start but hard to say.
Who did the machine work and assembly? There shouldn't have been any different noises associated with the LML crank. Who does the tuning as well? Something wasn't right from the beginning. Did you reuse the same block? The two that I have broken all happened in the same block and it was checked and machined again. That block will never see use again.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
AF cam shafts have a very distinct sound to them that is different than a normal firing order cam. And as stated the oval bowls make a unique sound as well. Was probably a combination of the two that he was hearing and nothing wrong with the build.
It would be nice to see a slightly cheaper option for a narrow journal crank for those of us that aren't going for an all out build. Possibly forged narrow journal crank, that should cut down on costs I would assume? Correct me if I'm wrong.