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Re: Crankshaft reuse?
[Re: mr111]
#1790563
03/31/15 07:27 PM
03/31/15 07:27 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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Quote:
As for the crank being welded, highly unlikely, this isn't the only place this happens, there's another journal near it that has something similar. In the picture I posted, there's another small pit in the upper right hand corner. I just can't see someone welding this thing from twenty pieces.
Cranks are welded to repair them, not put them back together.
If someone chews up an engine badly the rods can grind heavily on the crank journals. Pitted bearings can catch debris and wear down the crank like sandpaper.
A crank grinder can take that beat up crank, weld a bunch of material on the bearing journals, and make them big and sloppily oversized. Then, he will turn the journals back down to the original size.
*POOF*
Now your chewed up worn out crank is back to it's original dimensions and good as new.
HOWEVER, if the welder isn't that good or doesn't take proper care the welds can be porous. When they grind them back down to original size it will expose the little pin holes and imperfections.
Those imperfections are what I see in that crank. They can be found anywhere across a welded journal.
Little particles of metal, carbon, or other debris can be carried by the oil and end up between the bearing and the crank. Little holes will catch the trash. That's where it starts chewing up the soft bearings.
That crank either needs to be offset ground (gets rid of the pits) or welded up and repaired again.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: Crankshaft reuse?
[Re: feets]
#1790564
04/01/15 12:48 AM
04/01/15 12:48 AM
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Joined: Jan 2003
Posts: 1,791
Big Sky Country
MO_PA
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,791
Big Sky Country
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Quote:
HOWEVER, if the welder isn't that good or doesn't take proper care the welds can be porous. When they grind them back down to original size it will expose the little pin holes and imperfections.
I agree with Feets, that crank looks like it has been welded.
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Re: Crankshaft reuse?
[Re: Rhinodart]
#1790567
04/01/15 01:44 PM
04/01/15 01:44 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Chrysler built 750,000 440s and who knows how many 413s. I have a hard time believing that someone would weld up two journals on a 440 crank. That'd have to cost more than the core charge for a different crank.
Crankshaft welding is done by the submerged arc process and it produces a very good result. Heck, any weld is expected to not have porosity. It is not, as some posters imply, inevitable that a weld will have voids.
Any certified welder should be able to produce a weld with no voids using a flux coated welding rod, commonly called stick welding.
I mean really, I am far from certified but my stick weld samples passed guided bend tests. Chip off the slag and get enough penetration on the next pass to melt out any unseen slag inclusions.
My other clue is that the pits occurred in a line and not spread randomly over the surface.
My best guess is some sort of acidic material attack on the uncovered parts of the crank journal. I have seen pitting like that in an engine that blew a head gasket and got antifreeze in the cylinders, where it turned into something acidic, possibly glycolic acid. Boring the cylinders 1/2 mm, or 0.020", didn't get to the bottom of the pits, but it got close. The dark spots at the bottom of the pits were still visible after boring.
R.
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Re: Crankshaft reuse?
[Re: dogdays]
#1790568
04/01/15 06:44 PM
04/01/15 06:44 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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Nobody knows the history of this crank. It would have been welded by a hack.
Personally, I prefer spray welding shafts instead of stick or mig.
It's a good idea to have any welded crank heat treated after welding.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Price a new one lately? 
