Broken crank?????????
 

My buddy has a 555 ci (502 block) that had 45 hrs on it when the crank broke. He bought the crank from my marine mechanic. My mechanic told his engine builder that the crank was used and in good shape and had been magnafluxed (sp). This is what his engine builder told my buddy.
My buddy is all PIss OFF about the crank because the guy that sold him the crank will not do anything for him. I don't disagree with the seller of the crank. That is his call.

MY QUESTION IS:
Was the crank bad or could the engine builder assemblied the engine incorrectly? Example: Not balanced correctly. etc, etc. I know this could be a wide open question but thought I would ask.
The crank was a Lanati (sp)
The owner said the crank let go will cruising at around 4500.:confused:

also forgot to mention
 

my buddy hit a concrete sea wall at night head on. It damaged the front of the boat and fiberglass work about 6 inches in from the front of the nose. Could it have done engine damage?

I am not inferring that anyone did defective work, or sold bad parts, but I'm not surprised the seller won't do anything for the buyer. Used parts are normally "AS IS" unless a prior agreement is reached, such as contingent upon passing a mag particle test. The engine builder SHOULD have checked it for straightness, size, and magnafluxed it himself, rather than take anyone's word for quality. As to why it broke, hard to say.

The world I know
 

you don't even get warranty on new parts when it comes to performance engines.
A few do but most don't.

I gotta ask...
 

How the hell did he hit a concrete wall? DAMNIT... I hate it when that happens... did it abruptly stop the motor (like instantly)? How long after rockin out before the motor puked? I feel for the guy, it's a bummer no matter what (especially hitting the wall)...... I hear they hurt stuff

tooooooooo many beers and
 

not knowing the surroundings. He said the wall had no lights on it where he was at. He said he had been running about 50 mph and for some reason he backed off and when he did his docking lights shined on the wall. He said he crambed it into reverse. Got it slowed down but not stopped. He was very lucky. He was working out of the windy city so he took his boat from SC with him. He ran it a few hours in SC after hitting the wall. Then he ran it again this weekend. It broke on Monday afternoon late. 1990 27' Carrera.

Slaming it into reverse wouldn't be good for it.

I broke a crank at 7000 rpm once. There wasn't much left that was usable.

I wouldn't think that it was an assembly problem. He did get 45 hours out of it. Besides, what could be assembled incorrectly to cause a crank to break? If the oil clearances are off, it would spin a bearing before snapping the crank. I would bet the crank had a crack in it from the beginning. Maybe forcing the drive into reverse shocked the crank a bit and caused the damage to occur a little sooner, but I think it would have happened anyway.

The crank was used. It was second hand from a third party. And you want the builder to cover it? If you want the part to be covered, then it should have come from the builder. When he supplied the part, he assumed the liability.

That said, a buddy built a engine back in high school. He got about 45 miles on it when the crank broke. Turned out he forgot to torque one of the caps. Must of tried hitting the final torque value in one step.

keep'em coming
 

interesting

I agree with Checkmate, the crank must have had a crack. Also agree that if it did have a crack, sudden reverse shock could have made the crack propagate. As for the magnaflux job, I do that kind of non-destructive examination at my job. It is not all that complicated of a process but the part that takes extra care and attention is interpretation of indications (possible cracks). There are a ton of boneheads out there that wouldn't know what a mag partical (magnaflux) indication or actual crack looks like even if they fell in it. Plus, these guys can tell you they magnafluxed it but who really knows? Sleezy *$!@@!*$ all over the place out there! You have to get that kind of work done at a truely reputable shop (or bring it to me and I'll do it right). I feel bad for your buddy about the crank - about the wall though, did he have "beer-vision" that night????:D

Cord my buddy is pissed because the engine builder he bought the crank from will not
 

Quote:

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Originally posted by Cord
The crank was used. It was second hand from a third party. And you want the builder to cover it? If you want the part to be covered, then it should have come from the builder. When he supplied the part, he assumed the liability.

That said, a buddy built a engine back in high school. He got about 45 miles on it when the crank broke. Turned out he forgot to torque one of the caps. Must of tried hitting the final torque value in one step.

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do anything for him. Not the engine builder who built the motor for him. DID THAT MAKE SENSE:o

when you tear the engine down it shouldn't be too hard to figure out what happened. cut the oil filter open and look for metal, metal chips, or shavings in the oil pan, lay the main bearings out in order and look for signs of scoring from loss of oil and compare them to the journal that broke. a cracked piston ring or broken valve, gouges in the cylinder wall could indicate seizing of a piston. if there are no cylinder gouges, melted bearings, blue pistons, chips or shavings, and the caps were tight, i would guess you had a defective crank.
going from forward to full reverse is not a good thing but worse for the drive than the engine. the engine still spins the same direction just under more load. i'm surprised the drive survived.
sorry to hear of the damage, lunati has a pretty good reputation. they aren't cheap cranks.

Either way Mike, it doesn't change the response. If somebody bought a crank from you and broke it, would you cover it? No. You don't know anything about how the engine was built. If the builder used the wrong clearances, why should the crank seller cover the crank? If the crank was defective, why should the builder cover it? The buyer took that responsibility when he bought the part.

I bought a used 427 crank for my hot rod one time from a guy who was a reputable source for hi perf used chevy engine parts. He said, "It was just magnafluxed and turned .030 on the rods and .020 on the mains". It had a tag with the sizes on it and it was in a bag from a machine shop. I should have known from the journal sizes it had been around the block a few times, but I bought anyway and took it to my crank grinder to have him check it out........ 3 cracks. When I called the guy back, he got mad at me for having it checked before installing it in my motor. WTF... I asked for my money back ($350) and he said no way. I ended up giving it back and getting "store credit". I got a $200 dominator intake and a $50 set of valve covers. Now I only feel half screwed...... I feel bad knowing that somebody probably bought and used it.

Where exactly did it break?

DON'T KNOW YET.....
 

Will find out this weekend

Lunati does make good cranks.
I think a lot of it depends upon the stresses placed upon the crank. For example, we used to run 304 inch small blocks in NHRA comp eliminator to 10000 rpm. :eek:
We found cranked cranks all the time and ran them another 40 runs before trashing them. Why? In that setup, clearances are loose, very short stroke, and very light load. Cranks will last forever in that application. Valve trains are a different story;)
I guess what I am saying is that with the load and stress put on a high torque big block, any small crack in the crank can become problem real quick.
Used is used, your buddy is out of luck.

I broke one in two after only 10 hours, forged GM crank, never over 5000 RPM. It had been mag'd just before installation. Journals were cut undesize .010 from a prior spun bearing, but it didn't break near the journals with the bearing damage. I'll dig up a picture from my system at work on Monday if you want.
Broke right behind first throw, actually still ran that way but made some noise and oil pressure was way low :) .
-Greg

Engine builders have the upper hand in that there are so many other variables that must be considered before a warranty will be covered. Add in used parts and it may be impossible to really prove the engine builder is at fault. If it failed on the dyno or on initial fire up then there is a stronger arguement against the builder. If it lived 45 HRS, forget it. All a good engine builder can do is be sympathetic. My builder gets dirt cheap on his labor in the winter so if guys need some help he is glad to do it then for real good prices. The only other thing is to try getting the crank manufacturer involved, but I doubt they will do anything on a part with unknown previous useage and time. I learned a long time ago that used parts can be cheaper and more expensive than new ones.:rolleyes: