Broken Crankshaft Count?
- Thread starter EDP
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super diesel
<<<< Under Pressure
I still cant rule out at least some of these failures was the results of wasted oil that had been over temped at one time or another. After that, you lose oil pressure in a hurry (not nearly as good as it is with fresh oil, or at least that's what my testing showed). Crank contacting the bearing from the thinness of the oil (thermal break down) and it's all over. Mains are usually always the first to go in these situations. What are WE doing to keep the cooling system of the lower section and internals cool? Nothing! Were relying on the stock system to get us by. 
So would you be opposed to filling (or even half-filling) the block to stiffen up the lower assembly since that eliminates the cooling passages? Or if done, pay particular attention to a quality oil cooling system since that's all that's going to cool anything except coolant through the heads?
super diesel
<<<< Under Pressure
Well Mitch. this is my story and I'm sticking to it. On a race only truck the filling isn't as important (short runs). If you watch the you tube vedeo "Duramax LLY overheating", look at the oil pressure gauge around the 18 min mark. Looks like it's setting darn near on '0' . There's no comment in the video about it. It remains this way through the limp mode. As far as I'm concerned if you tow ANYTHING with these trucks for any distance (over 20 miles and maybe less), you should be sporting a good oil cooler (oil temp gauge minimum to keep it alive and the damage to a min). I temped mine up unloaded and just going up a 10 mile grade without the cooler. Once the oil is degraded, it's ability to perform more and latter is extremely compromised and your driving on a prayers (worst of all it's unknown to the operator unless you have that oil temp gauge). The oil is by far wasted BEFORE the oil pressure gauge shows signs of it reading low. It only takes once.
. There's no comment in the video about it. It remains this way through the limp mode. As far as I'm concerned if you tow ANYTHING with these trucks for any distance (over 20 miles and maybe less), you should be sporting a good oil cooler (oil temp gauge minimum to keep it alive and the damage to a min). I temped mine up unloaded and just going up a 10 mile grade without the cooler. Once the oil is degraded, it's ability to perform more and latter is extremely compromised and your driving on a prayers (worst of all it's unknown to the operator unless you have that oil temp gauge). The oil is by far wasted BEFORE the oil pressure gauge shows signs of it reading low. It only takes once.
I out went drag racing with a friend last year and he was hot lapping his LBZ pretty hard. It spun 3 mains at the end of the night. I believe that the oil was hot and thin, causing that to happen. Fast forward 15K miles after the motor was rebuilt, crank finally let go.......
Well Mitch. this is my story and I'm sticking to it. On a race only truck the filling isn't as important (short runs). If you watch the you tube vedeo "Duramax LLY overheating", look at the oil pressure gauge around the 18 min mark. Looks like it's setting darn near on '0'
X2, I couldn't agree with you more! The oil is the life of the motor, period.
At work I get crank failures often enough and in 6 years of looking at failed engines, it's never been a flawed crank, there's always signs of poor oil quality, or loss oil pressure, or oil contamination.
Most of us are so worried about in cylinder performance that we regularly neglect the most important part of the motor... to Super's point you'll never get the engine to live if you don't protect what's protecting your engine.
Most of us are so worried about in cylinder performance that we regularly neglect the most important part of the motor... to Super's point you'll never get the engine to live if you don't protect what's protecting your engine.
LMM with 44k and a PPE tuner (Broken crank near the front) but is not tore down yet because of denied warranty. My understanding of tech Bul 06-06-01-007c is that engine need to be tore down by dealer and needs to show proof that tuner caused prob but the warranty is not really my issues but do have Lawyers working on it. Issues being, am I the only one thinking casting prob ? heard of to many stockers with breaks in the same spot (2nd Jr). I do have more info (on poss casting flaws)im not willing to post on here but will IM it if wanted.
super diesel
<<<< Under Pressure
Over temped and compromised oil will do this even on stockers. #1 & #2 journals seem to have lower oil flow than the other journals (my pressure transducer was displaying this by a registering a drop off in pressures there). This and compounded with possible oil quality issues (may not be the case in every situation but seems to be heavy in that direction from my testing) doesn't help any.
Hope you get the issues ironed out with GM.
all my bearings and crank journals looked fine, imo. im no expert, but i would think there would be signs of crank/bearing contact on at least a few of the bearings if the oil was compromised and the oil pressure had gotten low causing contact.
looking at the area on the crankshaft where it broke, it is a very small area of material right there where it breaks. i think there are possibilities of casting flaws, possibilities of balance issues, possibilities of nitriding issues, and not sure what else.
looking at the area on the crankshaft where it broke, it is a very small area of material right there where it breaks. i think there are possibilities of casting flaws, possibilities of balance issues, possibilities of nitriding issues, and not sure what else.
super diesel
<<<< Under Pressure
Looks like a flexing issue (not slowly cracked through over time but a sudden break from fatigue). You said there was black on the casting. I can see it on the crank journal in the pic. This would be from a degradation and burning of some sort. The thing about a casting flaw would be that this would be far more common than it is (production issue). Hard to say what made it give up the ghost. When I spun my #2 bearing, the crank flexed and warped .005 out of tolerance but hadn't cracked or broke. Would it have if I had go much further? I'm quite sure.