wrist pin issues?

kleann

kleann

VP44 pwr
Joined
Aug 23, 2008
Messages
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Back in the summer I built myself a sleeved 6.7 engine. 6.7 block(sleeved down to 5.9 bore), standard size mahle cast 5.9 pistons(cut down to correct piston protrusion, slightly less than factory spec to account for hamilton 188), PTW clearances were looser than factory specs, although I will have to find exactly what I ended up telling the machine shop to make them. 6.7 crankshaft. R&R rods with bushings that came in them. All the wrist pins felt okay when I installed the pistons onto the rods, but I did not measure the clearances of these. The engine developed a light knock after a few passes. Ran it about 10 times in total. I tore the engine down and the wrist pin on #6 has major discoloring where it got hot. The rod/piston assembly would not fully rotate as far as the other rods/piston assemblies on the other cylinders, although it still rotated further than it would need to if it was in the block at where it is at the greatest angle. The piston on that cylinder must have been hanging on the rod because the cylinder and piston is now grooved. I'm not sure what the issue could be other than me not measuring the rod bushing/piston clearance, is that ultimately where I messed up? I'm a novice engine builder at best, but I figured it was worth a shot -- engine ran awesome other than the stated issues.
 

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Is the piston cooling jet okay?

Most of the time that starts out as a scored piston, then turns into a wristpin issue due to the piston distorting, the pin binds up in the piston, heat transfer to the rod, ect.
 
9724VF350 said:
Is the piston cooling jet okay?

Most of the time that starts out as a scored piston, then turns into a wristpin issue due to the piston distorting, the pin binds up in the piston, heat transfer to the rod, ect.
Click to expand...

Its look like all the others from the exterior, I will have to pull them out and see if it is clogged up. I found some metal shavings in the coolant system from where the sleeves were bored, so it is possible some could have gotten in an oil galley.
 
Improper wrist pin clearance, and maybe many other issues, looks bad.
 
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Thats wicked. Sorry to see that on a fresh engine. Has me paranoid putting mine together.
 
Could PTW clearance being too high cause this? I gave the machine shop 0.008"-0.012" for specs - 99% racing application, but then again, I don't have the tools to double check them when i was assembling it.
 
Broaner said:
Thats wicked. Sorry to see that on a fresh engine. Has me paranoid putting mine together.
Click to expand...

Do yourself a favor and buy the equipment to measure everything - wrist pin clearance, piston to wall clearance, main bearing, connecting rod bearing, piston protrusion, ring gap. And good name brand stuff. Also, torque wrenches. I was doing this on a very small budget. Probably could have saved money by just forking out the money in the beginning, and double checking all measurements, even the ones taken by the machine shop.
 
When you put it together did you have issues putting the wrist pins into the piston?
 
That's a bummer. Also a measurement I didn't check when I built my last engine. What kinda clearance should they have in the pin ?
 
Have any pictures of the wrist pin, rod and piston separated from each other?
 
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