-----Original Message-----
From: Orosa, Sixto
Sent: Tuesday, August 12, 2008 3:09 PM


Hi Dave,

I uploaded a folder called 603 bent rods.

Here's an explanation of the pictures:


#01 = left to right are pistons 1 through 6 viewed from the exhaust side (prechamber pit on the far side).  Note how central wear shifts to diagonal wear as you move away from the center.

#02 = left to right are pistons 1 through 3 viewed from the exhaust side.

#03 = left to right are pistons 4 through 6 viewed from the exhaust side.

#04 = left to right are pistons 1 through 6 viewed from the intake side  (prechamber pit on the near side).  Note how the skirts are not symmetrical intake side vs exhaust side.

#05 = left to right are pistons 1 through 3 viewed from the intake side.

#06 = left to right are pistons 4 through 6 viewed from the intake side.

#07 = #1 rod on a straight edge.  .006" gauge slips easily under the top edge of the small end.

#08 = #1 rod on a straight edge.  .008" gauge doesn't slip under the top edge of the small end.

#00 = #1 rod on a straight edge flipped from 4901/2.  .004" gauge slips under the lower edge of the small end.

#10 = #1 rod on a straight edge flipped from 4901/2.  .005" gauge doesn't slip under the lower edge of the small end.

These are the rods and pistons out of my 93 SD.  The block had a *lower* serial number than the datacard and it came with a #20 head.  #1 and #6 rods were bent forward about the car's pitch axis determined by the forward edges of the piston crowns being below spec above the block deck.  The aft edges were within spec.  I don't remember what the measurements were but I might have posted them on mbshop.com.

There was no detectable bending in the #3 rod using the same straight edge I used in the pictures.

FWIW, #1 piston pin slipped out easily after I removed the circlip.  #3 piston pin took some heavy thumb pressure to get moving but slipped out easily once it got moving.  I didn't notice any pitching slop between any piston and its rod.  I didn't notice wear in the #1 pin or small end or anything at all different from #3.

I wish I could do more analysis of the bent rods.  I'd like to know if they're generally bowed or bent about a weak spot like a hockey stick.  I don't think my level and feeler gauges are the right tools for that :)

I have pictures somewhere of the cylinders but generally the hone was intact, not notably more worn in #1 or #6 than the middle cylinders, and no major ridge or difference in ridge among cylinders to speak of.  All top rings look good for having slid past whatever ridge there was.

Block was scrapped.  Everything else was fitted to the .961 that got totalled with the SD. I have the head (no cam) and pistons and rods (#2-6 rod caps went to Michael LaFleur).  



Regards,
Sixto