Hi, I recently spun 3 rod bearings on a freshly built motor with only 400 miles. After disassembling the engine, i did noticed that the wrist pins on my crower rod/ wiseco piston combo were a bit tight.
I can manually move the rod back and forth, however...

When i hold the piston side ways, rod perpendicular to the ground.
(see diagram)
Piston-->[ ]==O<--- bearing side

If I pull up on the bearing side of the rod, and let go, gravity cannot pull the bearing end of the rod down.
(Am I making any sense?)

3 of the 4 rods spun a bearing. Each rod that had spun a bearing also had a tight wrist pin. The 1 rod w/o the tight wrist pin did not spin a bearing.

-Could the tight wrist pin be a cause of spun bearings?
-Also, has anyone ever had a probem w/ tight fitting wrist pins on aftermarket rod/piston combos?
-Any other input is appreciated.'

BTW: There are no signs of heat(ie blue/or discoloration) on the bushing end of the rods.

Thanks
Tim

 

possible lack of oil to the wrist pins and/or rods that had spun bearings......?

have you determined what caused such a new engine to spin 3 bearings?

 

There are signs of detonation. Lots of white blast spots on the piston. But only on 1 piston.

 

Check out the piston closest to the thermostat.

 

looks like #4 was the only one dentonation or running lean.......

which bearings spun?

 

1,3,4. #4 looked the worst out of the rest. I drove on it for about 10 min after hearing the knocking before the engine locked up. Assuming the 4th one gave out first, Could it be possible after the 4th rod bearing spun, that i was ran low on oil pressure, leading to the failure of 1 and 3?

 

i think maybe it was a oil pump/filter/pressure failure.

even the most extreme cases of dentonation shouldent cause 3 bearings to seize up........eventually over time dentonation will be a factor but only after 400 miles.......i doubt it.......

plus dentonation only occurs under heavy engine load.....so unless for the first 400 miles you were beating the snot out of that engine i cant see it doing that kind of damage......