Mystery rod failures

A small bit of info for those of you that don't already know. When installing and torquing rod bolts do not use anything that might be considered a quality lubricant. Any lubricant that does a really good job at reducing friction can cause problems. Especially if you do not normally hone the rod before installing. If you do hone your rods on a machine like my machine in the attached photo, first remove, lube and re torque rod bolts with the same lube you would use during assembly. And true the stones often. And lastly, if whatever you are doing now never causes any problems, don't go changing what you do. Also I found that anything much better than cheap motor oil on bolts is asking for trouble.
 

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That leaves more questions then answers .
Did the High Quality lubricant cause the rod bolts too loosen and fall out ?
Was the High Quality lubricant the solution to this Problem ?
Resulting in over torqued deformation of the rod bore .
 
I'm thinking the high quality lube caused over-torqueing of the bolts which the cheap Chinese rods didn't like... I never use anything more than 30wt motor oil on mine. The only time the moly lube comes out is with ARP hardware that requires it.

Captain- did you find the issue that was causing your problem?
 
That leaves more questions then answers .
Did the High Quality lubricant cause the rod bolts too loosen and fall out ?
Was the High Quality lubricant the solution to this Problem ?
Resulting in over torqued deformation of the rod bore .
The so called high quality lube can distort the bore. As a generalization, the better the lube, the more tension the bolt is placed under.
 
I'm thinking the high quality lube caused over-torqueing of the bolts which the cheap Chinese rods didn't like... I never use anything more than 30wt motor oil on mine. The only time the moly lube comes out is with ARP hardware that requires it.

Captain- did you find the issue that was causing
I believe that you are correct
 
different lubes will result in different pinch loads. ARP recommends using a mic to read the stretch of a bolt not torq specs. stretch is far more accurate.
 
different lubes will result in different pinch loads. ARP recommends using a mic to read the stretch of a bolt not torq specs. stretch is far more accurate.
Actually, when dealing with easily distorted aluminum rods, measuring the stretch is a recipe for disaster. Measuring bolt stretch yields poor results with aluminum rods. One bolt may reach the target amount of stretch at 90 inlb and the next could take 120 to hit the same amount of stretch. Your statement is mostly correct when dealing with a material like steel.
 
Actually, when dealing with easily distorted aluminum rods, measuring the stretch is a recipe for disaster. Measuring bolt stretch yields poor results with aluminum rods. One bolt may reach the target amount of stretch at 90 inlb and the next could take 120 to hit the same amount of stretch. Your statement is mostly correct when dealing with a material like steel.
or higher quality aluminum
 
I hesitate to post this, cause it's pretty shade tree,

As a quick check, when I built or tore down a motor, after removing the head I'd rotate to TDC and use two fingers on the top of the piston and try to twist the piston in the bore.
If it has rod clearance, the piston will twist. How much depends on how much clearance there is. After you do a bunch of them, you'll get a pretty good feel for the amount of twist equaling clearance.

They tend to wear more at TDC and BDC, I guess because that's where they change direction. :)
BTW, with a dingleball hone it's possible to crown the the rod bore, or have more clearance on the edges than the center.
 
I changed the above post because at the 90 degree points you would have the piston parallel with the bore, and the rod off to the side.
So the rod could slide on the crank journal, which would give the appearance of increased twisting. But I guess if it's sliding on the journal, it's got clearance. :)
Accurate measuring is still the best.
 
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