broken crank?
- Thread starter punkmechanic
- Start date
condor74
Full Access Member
not wanting to rig anything really but if the rest of the engine is still sound, couldnt you just bolt a new crank kit in there or was there more damage?
punkmechanic
diesel tech
I plan to put a different crank in it. I didnt even pull the heads. Gonna put new rod and main bearings and a crank in it and give it a go. It looks to be a really low mile rebuild, judging by the internals and paint marks on everything. It will take a good long while to trust this motor, maybe it will be my "loaner" for when Im rebuilding one.
punk
punk
dyoung14
Is getting worn out
what happened to your re-man engine that was in the truck back when i talked to you on the phone that time you said it was a gutless wonder did it kick the bucket or something?
david85
Full Access Member
Is there any way to reliably verify that the mains in the bottom end are still strait. I'm thinking that if either the block or the crank were not perfectly strait after an impact (if that was the problem) either could have stressed the crankshaft into snapping.
That might be total BS however, since I am still a novice when it comes to building engines.
That might be total BS however, since I am still a novice when it comes to building engines.
LCAM-01XA
Full Access Member
What I'd like to know is, what's up with the accessories setup? That ain't nothing like what you find in a pickup truck, not usually at least...
dyoung14
Is getting worn out
what i dont get was how it was still holding together to pull the cam and injection pump?
SparkandFire
We're drinking beer
What makes a crank break like that? I understand a bad machine shop job could make it fail, what do they do to it???
cetanefreek
Full Access Member
take the block down to a good machine shop and have it line-bored.
many have speculated that is the reason the GM 6.2's break cranks so easily, the block is kinda weak and it flexes. so yes yours is a valid concern.
punkmechanic
diesel tech
dyoung, this is the reman It was supposedly a known good engine that came with my buddies truck when he bought it. His truck supposedly needed an engine, turned out it needed time and return lines.
It broke across the throw for the 1-2 journal. The mains held the crank shaft so that the pieces lined up and the cran would still turn.
david 85, I think this is fine. All the main bearings looked reusable except for the one between the front main seal and 1-2 piston journal. That one took the brunt of running with a broken crank and wore through the babbit into the copper. It didnt transfer heat into the main cap (that I can see) so Im just gonna stick a crank in it and see.
mlsc, Im not sure what your talking about. That engine looks the same as the other two I have on the shop floor at the moment. I assume you mean alt, p/s, vac, etc. by accessories. Please fill me in and I will answer as best I can.
spark and fire, I suspect that they either dropped it or reground the crank and had a knick in their grinding wheel. It snapped at the point where the crank connects to piston rods 1 and 2. It is about 1/8th inch toward the center line (mains) up from the rod bearing surface. I looks like they didnt radius the ends of the grind correctly and some knick or burr caused a hot spot that cracked and spread. No real way to know for sure, but that is my best idea on what I see.
punk
It broke across the throw for the 1-2 journal. The mains held the crank shaft so that the pieces lined up and the cran would still turn.
david 85, I think this is fine. All the main bearings looked reusable except for the one between the front main seal and 1-2 piston journal. That one took the brunt of running with a broken crank and wore through the babbit into the copper. It didnt transfer heat into the main cap (that I can see) so Im just gonna stick a crank in it and see.
mlsc, Im not sure what your talking about. That engine looks the same as the other two I have on the shop floor at the moment. I assume you mean alt, p/s, vac, etc. by accessories. Please fill me in and I will answer as best I can.
spark and fire, I suspect that they either dropped it or reground the crank and had a knick in their grinding wheel. It snapped at the point where the crank connects to piston rods 1 and 2. It is about 1/8th inch toward the center line (mains) up from the rod bearing surface. I looks like they didnt radius the ends of the grind correctly and some knick or burr caused a hot spot that cracked and spread. No real way to know for sure, but that is my best idea on what I see.
punk
probably got dropped at a wrecking yard and also tam has been known for not properly dressing the radius on the grinding wheel for the larger radius that a diesel crank needs. Look for cracks around the front of the main boss, I bet it is ok. that is a thick bulkhead.
THECACKLER
Full Access Member
( again ) Cranks break from Torsional Vibration. More commonly to the front than the rear because the flywheel helps dampen the vibrations to the rear. There is little that can be done to avoid these vibrations so engine designers try to adjust the harmonics of the engine to keep the Critical Speeds out of the power band. I've seen mismatched cylinder heads destroy both the HB and the Crank. Use as heavy ( massive ) and good Harmonic Balancer ( Torsional Damper ) as you can. As far as the case involving the Frontal Impact I would not wory about the block, it was more likely that if anything was damaged it was the HB. Anyway, I've heard that Fluidampr makes one for the 7.3 but I've not seen one yet. Here's a short blurb from them. www.fluidampr.com/TORSIONAL.html
Again, not just the vibration can break a crank. Inherent flaws, poor workmanship, dropping it, the list goes on and on, doesnt matter how, its broken now.
LCAM-01XA
Full Access Member
Ya know what, I just realized what we see in the video is not a direct look at the engine, but a mirror image of it - notice how your PS pump seems to be on the passenger side while the alt and the vacuum pump are on the driver-side, that threw me off at first till I noticed the PS pump bracket and how that's positioned in your video, it all made sense then
punkmechanic
diesel tech
I want to try and clear up some stuff, as Im getting a little lost in the questions and wondering where the question originated.
This engine by all appearance has never been dropped, wrecked, impacted, or (by everything but the crank) abused.
It was rebuilt by tam engineering and from the looks of it, they will never have a hand any anything I build. ****** workmanship kills motors, tam let at least one go with ****** workmanship.
I plan to reuse all the compontnents and stuff another crank in it. I dont know how much damage to rods and what not was caused (if any) by running it, so I wont put it in a critical rig, just in case it finds another weak link and goes down.
Right now the main concern is getting the known good running (not knocking) engine I pulled into the pearl so she is back on the road. Then Im gonna rebuild the pearls original engine for future use, while im working on that I also have a bronco that Im stuffing an early stroke in.
My garage currently has 1 running idi, 1 idi with worn rings and bores (pearls original engine), 1 idi with broken crankshaft, 1 95 7.3 stroke, 1 c6 2wd auto (selling it off, dont like 2wd or auto, lol), 2 rear axles, at least 8 turbos (benz, and strokes), 1 disassemble mb 5 cyl diesel, and Im still acruing parts. I like to build engines but this is getting kinda crazy.
punk
This engine by all appearance has never been dropped, wrecked, impacted, or (by everything but the crank) abused.
It was rebuilt by tam engineering and from the looks of it, they will never have a hand any anything I build. ****** workmanship kills motors, tam let at least one go with ****** workmanship.
I plan to reuse all the compontnents and stuff another crank in it. I dont know how much damage to rods and what not was caused (if any) by running it, so I wont put it in a critical rig, just in case it finds another weak link and goes down.
Right now the main concern is getting the known good running (not knocking) engine I pulled into the pearl so she is back on the road. Then Im gonna rebuild the pearls original engine for future use, while im working on that I also have a bronco that Im stuffing an early stroke in.
My garage currently has 1 running idi, 1 idi with worn rings and bores (pearls original engine), 1 idi with broken crankshaft, 1 95 7.3 stroke, 1 c6 2wd auto (selling it off, dont like 2wd or auto, lol), 2 rear axles, at least 8 turbos (benz, and strokes), 1 disassemble mb 5 cyl diesel, and Im still acruing parts. I like to build engines but this is getting kinda crazy.
punk
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