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3406E crankshaft breakage

27K views 12 replies 11 participants last post by  bigcat06 
#1 ·
Maybe someone could give me an idea understanding what causes a crank to break in a 3406e while cruising down the highway at 65mph. Thanks
 
#2 ·
Whatever it was that caused it to crack in the first place. Just finally gave out.

Out of balance, abusive driving (i.e. severe shock loads),..............
 
#3 ·
If it breaks at the #2 throw it is from the belts to tight, That is the area and cause of most breaks.
#5 throw is usually from the transmission being loose.
Tell us where it broke, and pictures, of the break area.
 
#4 ·
There are alot of reasons posted on here, but the real reason is because Cat admitted to having a supply of defective crankshafts. Ynot explained this sometime ago. Particularly the 5EK and 6TS series. I had one of each to break at the #1 journal. Both had less than 800K miles.

I had a Cat service bulletin at one point explaining this. I'll try to find it and post.
 
#6 ·
Yea right and the metallurgical guys were involved the machinists and the guys that do the testing the engineers that designed it, the truck driver that took it to the assembly plant and the machine that put it together. Everyone was to blame and the Management got a performance bonus. Those dam workers are destroying the economy.
Did I hit all the Frank Luntz hot buttons.
 
#8 ·
It just gets a little stale when it is always a union member, that cased the problem the Cam problem went on for years, I only saw one crank broken and that was from the belts. These defective cranks were was it they broke?
The cams were not a strong point for the B or C let alone the "E".
The rollers failed, the rocker arms bent, studs st reached, was that all someone else's fault?
Every batch coming out of the pot in a foundry, there is a sample taken for testing. someone with a lot higher pay grade than a union member has to OK every batch.
We all know it could not be CAT trying something different.
I was working at and engine dealership when Detroit had a huge batch of defective Cranks there was not talk about a conspiracy they recalled thousands of engines and replaced them with new one's. Thousands of engines because a key way was cut into the nose cone fillet.
What did Cat do? I never heard of a recall, what was the number?
I did a lot of Cat work and always went on line looking for any recalls according to serial number. If it was not done by the service writer.
 
#12 ·
Not even gonna read this, but yes, IT WAS NON-UNION STEP IN'S THAT FUBARD THE IRON IN COMBO WITH HARDNESS PROCESS WHILE IN THE MIDST OF THE EVER OCCURING STRIKE MODE THEY GO THRU EVERY FIVE OR SIX YEARS, HENCE THE SAME BREAK IN THE SAME PLACES ON ALL THE CRANKS THAT BROKE. This can be traced back to the first "strike motors" in '87. We all have heard that nomenclature used at times over the years. All I'll say, cept... hell never mind. Just a thought............................ :bdh But in all actuality, being it was 4 + people out of the Mossville plant, yep, that would actually be "text book" conspiracy as more than two people involved is illegal conspiracy. Good call :) And if it was you, would you TSB, PSP, or PIP a CRANKSHAFT times 180 thousand + at $15K to $34K equaling around 4.5 billion dollars PLUS or just shut up, feed lines, and fix the ones that broke, when they broke, as apposed to every single guy with a 5EK and up freaking for a new crank; faulted or not.
 
#11 ·
I can only comment on what cat did for us: Our 5 e k motor broke a crank well out of warranty and cat replaced it. when we ask them why they did not recall these motors they said it was cheaper to just replace them as they broke. I guess that's their call,right or wrong, but they did stand behind their defective product in our case.
 
#13 ·
Most time casting flaw. If you look at the break, see if you can see where the crack started. If you look real close it will be smoother waves where it has cracked and vibrated smooth, then it will be real rough when it breaks the rest of the way. When you find the smooth area look for any imperfections. I just had one that broke and you could see what looked like a bubble in the casting.
 
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