Lose power, backfired symptoms, then noise in that order.. Apologize for not making that clear..
Someone asked where/who was helping me.
http://www.cfdieselperformance.com/
Help: Need shop in Boca raton/Miami Florida
- Thread starter malibu795
- Start date
Lose power, backfired symptoms, then noise in that order.. Apologize for not making that clear..
Someone asked where/who was helping me.
http://www.cfdieselperformance.com/
This better?
Cracked, broke over time. You can see where crack started, and then got "polished" over time. The shiny part is where it started. One thing bout being a machinist, I see sheared pins almost daily:spit:
JMHO
The reluctor gear has a nice shinnny ring/grove around the inside of it and the keyway has a bulge on it
With that said.. Went through my fuel receipts for this trip...first tank was 9.5mpg through southern ohio to southern tn 8.5 through GA. From FL GA Line to out side Miami was 7.5. I figured it was heat/humidity since that has been issue of MPG drop in the past.. and FL is alot flatter then kentuckey, Tennessee ,Georgia and Ohio but hotter and more humid substantially.
Never really notice a mph drop on hills I was ~28,000gross so any serious long grades I dropped to 4th and cruised up at 58mph.
Snapped a picture
Ouch! 
I am a duramax guy. It is just hard to argue with the data my customer has collected. I love my lml, dont get me wrong but a snapped crank is always in the back of my mind...
This better?
Pin sheared from left to right. Which is weird since the crank should have been turning that direction and you would expect the break to go the other way if the gear suddenly stopped while the engine was rotating forward.
Polished surface is from the gear keyway cleaning off the top of the broken pin as it went by. Burr from the keyway pass is visible on the right side of the broken pin. Indentation on the gear keyway in the other post confirms direction of impact forces at failure.
Galling on the Dampener face of the gear would indicate that the gear was moving around a lot but I don't see matching indications on the cam pinion gear face. Would like to see other side of the Reluctor/Oil pump pinion gear.
I would say the pin sheared after the crank broke and was not the cause.
Any misfire strong enough to break a crank would have definitely bent a rod.
Is it the photo, or is there one heck of a witness mark on the front side of the #2 main cap.
Even at ~400hp? I know few have broke pistons lifted heads etc at the current level I'm at
I'm an idiot, I always run a 550 rwhp tune even towing. I guess I'm on here too much though, I probably read about everyone in the country that breaks...
I'm an idiot, I always run a 550 rwhp tune even towing. I guess I'm on here too much though, I probably read about everyone in the country that breaks...
I know of 3 trucks from around my area that have snapped cranks. 1 was a bone stock lmm with close to 100k miles
The other 2 were LML's with over 200k. Not sure of mods but they were hot shot trucks.
I'm an idiot, I always run a 550 rwhp tune even towing. I guess I'm on here too much though, I probably read about everyone in the country that breaks...
My motor has not seen a smaller tune than 600rwhp accept for break in and I tow all the time on it with wot runs in the mix. So far temps in the summer and killing clutches has been my only down fall. 35k on it since built and 200k on the crank
With all the crank failures we know of, pulling heavy certainly does not help, and heavy, I mean past GCVWR... 28k is CDL territory.
I fall under class A CDL at 36,000lbs
Have you considered maybe lowering your gear ratio to a 4.10 or lower to help reduce the engine load when loaded down? Running at those kind of weights, I would think it would help reduce some of the engines load and maybe reduce some of the stress on the crank if you lowered your ratio to increase your RPM's at cruise. It wouldn't help your unloaded milage, but I would think it would help when loaded down.
Been thinking about it for a while now.
With current setup.. I turn in 5th
1900@70 3.73:1/32" tire
2100@70 3.73:1/30" (OEM)
2100@70 4.10:1/32"
2300@70 4.56:1/32
My 99 3500 HD had 4.63 and ran 2500rpm @70
Figured reduce engine load my EOT would drop as well
Engine falls on its face below 1800rpm especially noticeable with heavy loads..shows up better with the. Bigger charger as well.. Naturally
With current setup.. I turn in 5th
1900@70 3.73:1/32" tire
2100@70 3.73:1/30" (OEM)
2100@70 4.10:1/32"
2300@70 4.56:1/32
My 99 3500 HD had 4.63 and ran 2500rpm @70
Figured reduce engine load my EOT would drop as well
Engine falls on its face below 1800rpm especially noticeable with heavy loads..shows up better with the. Bigger charger as well.. Naturally
With my 4.56s and 37, I turn 2100 at 70mph in 5th. It's night and day better compared to the 1800 at 70mph in 5th with 3.73s and 37. 4.10s would be awesome in your rig
I still got 6th. But barely use it.. Due to fuel consumption/heat goes up in current setup
I mentioned about the towing Duramax failures in your piston failure thread because I feared this would happen. Buddy is a diesel tech at a rural GM dealership, seems duramax's that tow alot grenade engine hard parts more often that I would have thought. Stock to moderately modified. No brand is trouble free, I've owned all 3, but, at your towing/power level, the Cummins is a more suitable motor. In my eyes it is totally unacceptable to break a piston and a crank at 400hp, especially in a truck that works for a living.
Side note:
I've always been a GM guy. I started with a Duramax, went to Cummins, bought a second truck that was a Powerstroke, then sold it and got another Duramax, then sold that one and Cummins still remains. Had numerous other diesel trucks for work. Honestly, I've had fewer paralyzing issues with my 1997 Dodge at 550hp than with the Powerstoke, which had less issues that either of the Duramax trucks. My last Duramax left me stranded 3 times and I was always waiting for the next issue. I had to ship it home truck freight from NM one of those times. Everyone talks trash about the rest of the dodge falling apart, but in my experience it's just not true. It's just cheaper and easier to fix and has less moving parts and issues. The only bad part is you don't get an Allison, but that's why I put a G56 in mine.
Hope you're up and running soon!