Cracked Rods...

[Blk Mamba]

.. at work today, one of my immediate tasks was to inspect cracked rods. They are completely machined, honed, drilled, and tapped, then they break the crank end to be able to install them. We were talking about this process, and one man said you have them in your car. Is this right, I sure hope not.

[Raven34]

Cracked powder rods are in all 4.6 2v n 4v EXCEPT 03 04 cobra. Why do you hope that you dont have this?

[Blk Mamba]

The reason I'm inspecting these is a flaw in the process.

[Raven34]

Hmm interesting, well its a common design in most vehicles. Im assuming this flaw in the process would only affect rods that are currentlt or recently being produced.

[Blk Mamba]

It is a flaw as to where they are cracking, making it difficult to assemble.

[tbone]

Weird post. ?? REPORT the problem!

[RoyLPita]

I have 8 pistons and rods from another MM engine. There is a painted line on the sides of the rod. This helps in mating the two pieces together.

[Blk Mamba]

This is for a company I work for, not the MM, I do receiving inspection, with a CMM, and the angle of the fracture prohibits the installation of the rods once the pitons are assembled.

[FordNut]

The cracked powdered metal rods have been used in the 4.6 since the introduction of the engine in the early '90s

[RacerX]

It is a flaw as to where they are cracking, making it difficult to assemble.
That's why there are inspectors! :D Once inspected, then installed, they can withstand a lot actually before catostrophic failure. Lots of guys on here pushing the envelope with stockers a-ok.

[EMAS]

Well I sounds like you have a flaw in your process. As others have mentioned Ford pioneered the cracked-cap rods with the first modular in the early 90's. Since that time the method has become state of the art, with many other mfgs using it successfully.

[Blk Mamba]

We don't have a flaw in our process, we don't manufacture the rods. Ford pioneered this process in the early '80s, about '83, still if you knew the way metal fractures you would know it happens at a point of weakness, all the time stressing the entire rod.

[liquid]

From my anecdotal knowledge it would seem that most catastrophic mod motor failures are not caused by connecting rods. More like inadequate cooling, spark knock, or oil starvation.

Excerpt from a 1991 article in ASME's Mechanical Engineering (http://www.allbusiness.com/professional-scientific/scientific-research-development/155655-1.html) magazine:

"With cracked powder-forged connecting rods, the crankshaft sees as round a bearing hole as we can economically provide," said Pete Hoag, manager of the crankshaft design team at Ford's Romeo, Mich., engine plant. "The rough irregular mating surface that forms when the bearing cap is physically fractured from the rod virtually eliminates cap shift." Both out-of-round crank bearings and cap shift can increase interference forces within the bearing, which causes wear, he explained.
According to Ford product design engineer David A. Yeager, "Even after long-term tests on production engines, the bearings still looked great. There were no visible wear marks and almost no cap shift."
Besides improving engine performance the innovative technique used to manufacture the connecting rod saved millions of dollars of expenditures on production line equipment. For its efforts, the research team that developed the connecting rod cracking process, which included Yeager, Hoag, and principal research engineer Daniel W. Hall, has received the automaker's Henry Ford Technology Award.
Really an interesting read! Apparently they investigated cooling the rods with liquid nitrogen for a clean break...

[J-MAN]

Thanks for the above info. A most interesting read indeed!