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(eagle 383 rotating assy) crankshaft broke>final update
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Post (eagle 383 rotating assy) crankshaft broke>final update 
I have to drive back to my Dads today to "try" to find out what exactly happened. Yesterday I just filled up with a tank of gas and was on a Hour drive to a family event with a date when something started sounding different at a certain rpm... like a weird vibration or exhaust leak at the header flange when taking off..... well after passing a few cars that wanted to drive slower than I wanted to since I was running late.... I made it to the next town and the belt started squealing and the motor started knocking slightly and skipping on a cylinder or 2. I drove it about 2 more miles to a advanced auto parking lot and popped the hood...... the Harmonic ballancer is jumping up and down about 1 inch or so out of round....
Well I made it to the family event 45mins late but on a wrecker Smile
I am getting tired of this $hit breaking down on me... I know 100% I put the motor together correctly and with all the quality parts and didn't cut any corners except using a "CAST" crankshaft that is the only thing I can see would have failed.
We will see.
the 6.0L LS motor is sounding better might just go and buy me a truck with it already in it and part out this one or just sell it to someone with a 350 in it or if someone wants this truck cheap.
Robby



Last edited by stroker97k1500 on Mon Dec 22, 2008 9:41 pm; edited 6 times in total
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Well that sucks. Any chance it's just the crank pulley that's tweaked or is the balancer definitely all over the place?

This sounds like my situation right before I switched to the 6.0L...

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Ahh that sucks Rob. I hate hearing strories like this. I'm hoping that its just your balancer thats busted up.

I dunno about a 6.0, but these GM crate engines are looking better and better the more horror stories I am hearing.

Personally I dont consider using a cast crank as skimping at all. Not needed IMO unless using forced induction. The 400's used cast cranks and held up fine. And they were swinging more weight than a 383 does.

Maybe an engine retrofit into your current truck? I dont like the GMT800 GMT 800 trucks, too heavy, bad rear brakes(until 2005 went with larger front rotors and back to rear drums) and the worst part IMO BCM's.

If you do like the 99-07 GMT 800 GMT800 trucks, I might find a nice 4.8l truck you like and drop whatever you wish into it.

Good luck man, let us know what you find. My fingers are crossed for ya.

peace
Hog

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Well I have a small update,...somewhat...
I pulled off the top half of the fan shroud, belt,and removed the center bolt in the crank snout/balancer. I can move the balancer up and down 3 inches both ways or so with feeling the hole of the crank snout still inside the balancer snuggly and I can shake it around like a limp noodle. What I dont understand is that the motor will still run and is evidently turning the cam/ timing chain ect. but I cannot just pull the balancer (with broken part of the crank inside) out through the front timing cover.
I just haven't gotten the "drive" yet to pull the motor out again or dig in too deep as of today... I have to go and get a engine hoist from someone first.
Robby

edit:
just removed the balancer and with the little bit of crank snout sticking out, I can wiggle it all around but not able to pull it out the hole of the timing cover. the only thing I can think of is that the break happened on the the 1/2 part of the counter weight and it is still pushing against the other "front" part of the crank in order for it to move or rotate with the rest of the engine and still keeping in time with the camshaft...
I'll try to get it ready to pull out and tear down hopefully in the next week or comming up weekend. Thankfully dad is loaning me his little trash truck to drive for a little while.

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Robby:

Man, I am so sorry to hear about this! That really is just horrible, rotten luck....

Fred

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Post HERE ARE SOME PICTURES OF WHAT I FOUND 
















I will be in contact with Eagle about this.
I am not even comfortable with using this block after having it machined again with the counterweight cutting a groove in the back side of the front main journal. I even took out a loan for the parts for this engine and because of their defective crankshaft, my entire assembly is now useless.
I am a little frustrated with Eagle at the moment, but I will see if they are going to make it right with me and I'll refer the person I talk to there to the pictures here on this page.
Robby



Last edited by stroker97k1500 on Sat Nov 08, 2008 6:16 pm; edited 2 times in total
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Man, I'm really sorry to see this... that really, really sucks. Totally unacceptable on the part of Eagle on this one, as I really don't see what could have possibly caused a failure of that magnitude (in this case at least) other than simply a defective crankshaft. Again, hope they are of some help to you on this.

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That's just crazy. It's externally balanced right?

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Thanks,
It was actually internally balanced. I bought a new (neutral) front balancer and flexplate (for the engine build) and went as far as using ARP flywheel bolts to prevent any potential vibration issues that could have (but not likely) developed by re-using old the bolts.

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Oh man, that make my stomach turn.

Where Bent1? I think he was the one that had some good insight when James broke the snout off his crank. IIRC He was able to "read" the failure on James crank when his forged GMPP piece snapped the snout off.

That sucks man. Keep us informed.
peace
Hog

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Some info...

5 WAYS TO BREAK THE NOSE OF A CRANKSHAFT



In recent months we have had numerous questions and issues raised about the nose of the crank and what can cause it to break. What we have found is that in most cases the crankshaft gets the blame for such failures. But in fact, it is the parts that are being used in conjunction with the crank, it is the additional machining done to the parts that are being used with the crank, it is 99% of the time NOT the crank that caused the crank to break.

1. IMPROPER MACHINED CRANK GEARS

A. Champher machined at wrong angle.

B. Champher machined with too small an angle.

C. Belt drive gears.

The seal sleeve bottoms to the face of the main before the interface of the gear bottoms against the step in the nose of the crank. All of the above prevents the crank gear from bottoming against the step on the nose of the crank. This leaves a gap between the gear and the step, which allows the crank to flex ...A fatigue crack starts. SNAP!!!! The crank breaks.

2. DAMPERS WITH MOVING INERTIA WEIGHTS - .Fluid, balls, springs, inertia rings with rubber O-Rings, etc. Can you balance a wheel on your race car if the tires are flat???? How can your rotating assembly be balanced if to quote one manufacturer," These units (Dampers) should not be on the crank for balancing as the inertia weight may not be centered until the engine starts. "NEWS FLASH!!!! Centrifugal force will always take the inertia weight off center no matter what RPM. Your assembly is never balanced. TELL TALE SIGN!!!! Metal transferred on nose outside diameter and damper internal diameter ...A fatigue crack starts. SNAP!!!! The crank breaks.

3. EXTERNAL BALANCE vs. RPM - Rotating weight multiplies as RPM increases. Engines have heavier or lighter balance weights and larger or smaller noses. RPM above 5500RPM is more risky on a Small Block Chevy than a Big Block Chevy. However, as RPM’s go up, the weight more and more wants to leave the crank due to centrifugal force. Do not be surprised if at some point fatigue sets in and the nose comes off.

4. DRIVES EXTENDING BEYOND THE NORMAL DISTANCE ON THE NOSE - Multi-stage oil pumps, blowers, etc all have belt drives that require torque taking off at 90 degrees to center line of the crank. More torque is necessary for driving these things and further away from main bearing support all leads to multiple of leverage wiggling the nose. Fatigue sets in, nose breaks, blower stops. The Small Block Chevy has the smallest diameter nose and the weakest of all. Note: Blowers take substantially more 90 degree torque than dry sump pumps, therefore, more likely to break noses. Not recommended for Small Block Chevy. If a blower is being used, use a crank with a Big Block nose.

5. IMPROPER BALANCING TECHNIQUE - The counterweights on a crankshaft are designed to work all together as a system within a certain bob weight range. To correct the balance on a crank where the counterweights are too heavy the following should be followed:

Internal Balance: If more than 2 holes are required in each end, the outer diameter of all the counter weights should be turned in a lathe to correct the out of balance condition in all the counterweights. If you try to drill more holes, you will create a secondary wave which will lead to crank flex and eventually a fatigue crank.

External Balance: The crank is spun with the external balance and flywheel. If it is determined that the assembly is too heavy where the weight is on the damper and flywheel, do not make the correction on the end counterweights of the crank. The out of balance condition is in the damper and flywheel, which is where it should be corrected. It is very simple to alter the bolt on weight of the damper and drill the balance weight on the flywheel. If these components need to be replaced simply bolt on the proper weight to the damper and match balance the flywheel which has to be balanced anyway. If you correct in the end counterweights, you will create a wave in the crank which will wiggle the nose of the crank which well eventually start a fatigue crack which will snap the crank.

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Man that sucks, I have heard a few people that dont like Eagle stuff because of the lack of quility. I ran some eagle rods in a big block I built a long time ago and didnt have a problem with them, but maybe those people were right.

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Sad and sorry to see this.

Why I've always gone to a forged crank whenever building an engine of 'mine'.
Any cast iron crank I've ever installed, insisted that it be shot peened after machining,
straightening and balanced. Just don't allow it to get too hot from shot peening.

Cast iron is fine, but the issue is that it is brittle and how it is handled so important.

It must be stored in the vertical position. Either on end on a table/shelf/etc, or hung
vertically by a string/wire/etc. If it was bent, even ever so slight, it will break usually
at the ends...like this one.

I've seen a bunch of them knocked over at a machine shop (I didn't do it, but another
customer did) like a row of domino's. Tried to tell the machine shop owner that they
were now all suspect and needed to be magafluxed. He didn't see the need to, so
that filtered him out as a potential machinist for my stuff.

Even if some of them were forged, I'd have had them checked out and then suspect
for high end engine.

Cast iron is way too easy to stress and create tiny cracks. The foundry where I had
my 48* dia disc brake rotor had a rule on the floor that if any of their cast iron
product was ever dropped hard enough to 'hear', reject that part.

The break has two planes, which inidcates initial break and secondary break. Which
is which tough to see and telling or pointing to what happened. There are two discoloration
areas and think oil, but if rust, tells that was busted before the clean area.


Usually look for pounded smooth spots, which says that area broken before the rest. But you
drove it a while after the noise, so no telling using that. Plus since inside and under pressurized
lube, there 'should be no rust', but if those two spots are rusty, I'd say there before you put
it into your engine....mean it was cracked before.

Since this break is between the bearing journals, to me, points to a weakness before the
out of balance did it's dirty deed on that stress raiser.

The nose breaks I've seen are all on the other side of that bearing journal, but if the vibration
high enough, just this side of that bearing journal. A lot of that has to do with the out of balance
and alignment sync'ing up just right.

If you don't mind, how's about a few more pic's but with a side light to shadow in the texture
of the surfaces.

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Forgot to mention that this looks more like a bending vs a torsional break

BUT, the two planes or surfaces kinda sorts tells another story, especially
if those dark spots are rust.

If there was a tiny crack before the crank was put in, then it could just
about any thing in any direction that broke or finished it off

If that is rust, think you have a case against the supplier or builder or
who ever had/handled/etc it before assembly into the engine.

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Hey Bent1,

If you hang a crank by a string and tap on it to hear what sound it produces? If it rings its probably not cracked but if it thuds then its cracked. Any tructh to this?

Obviously not as relible as a Magnaflux process.

peace
Hog

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I think the crank was partially broken for a few miles due to the weird vibration I was feeling. But it must have either worn the main journal bearing out enough to where it snapped off or where I really could tell there was a serious issue when it started skipping all of a sudden and the belt was squealing. I might have ruined any chance of reading the fracture by driving it to the nearest parking lot for about 1-2 miles but I didn't really have much choice.
here are more pics... I think the rusty colors were just oil on the crank.
EDIT: I am learning to use this camera... the close up pics were blurry so I deleted them... I will try the "macro" setting on the camera and re post
The Macro setting makes a difference... here are those:


















Here are the old ones that weren't very good.











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I just wrote Brian at eagle and forwarded him here to these pictures. I will let you guys know what he says to me.
Robby

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Sorry to see your having trouble, best of wishes with Eagle. Hopefully they will take care of this for you.

Wes

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Wheres the balancer? Its not in any pic. Its a "neutral" balancer that you bought but was it part of the balancing process as was the flywheel. Im not doubting you or your machine shops inteligence just asking a question.......Lorne

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