slight scores on forged pistons (removal?)
04-13-2012, 06:09 AM
#1
slight scores on forged pistons (removal?)
removed these pistons after an oil pump failure and there were some scores on the block and also a few on the pistons. they are not really deep but it cant be good. not going to replace the pistons so what is the best thing to do?
maybe a little rub with some scotch brite or a little wet n dry just to take away any burs there may be. options please?
maybe a little rub with some scotch brite or a little wet n dry just to take away any burs there may be. options please?
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04-13-2012, 10:54 AM
#2
Remove the rings, first, so no grit can be held in by the rings.
Just a light touch with 1500-2000 grit wet dry, do it under the fluid in the parts washer.
Just smooth any high spots you can feel with your finger tips, sand in the direction of the factory machine marks.
You should still see the factory machine marks, and some of the score marks when done.
Mic the pistons for size.
Wash throughly, oil wrist pin
Just a light touch with 1500-2000 grit wet dry, do it under the fluid in the parts washer.
Just smooth any high spots you can feel with your finger tips, sand in the direction of the factory machine marks.
You should still see the factory machine marks, and some of the score marks when done.
Mic the pistons for size.
Wash throughly, oil wrist pin
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04-13-2012, 01:22 PM
#4
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If you leave the rods on how can you ensure that the pin to rod bearing area stays completely clean when sanding the piston? That would be a concern I would have. Can piston pin end clips be used twice or more?
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04-13-2012, 04:45 PM
#6
landrew.. good question, On most full floating set ups there is appox .0005 wrist pin to rod clearance in the small end.
A sheet of notebook paper is appox .003 thick
.0005 = 1/6 the thickness of a sheet of notebook paper
As long as the movement of the wristpin/rod/piston is smooth, and does not feel "gritty" when you move the rod on the wrist pin all will be fine.
If any debris is left from the smoothing, that didnt get flushed away, will proberly be about the same in size as what you would find in your engine oil when you change it at 3k miles.
The big thing is to make sure the oil galley holes in the crank are clean.
A sheet of notebook paper is appox .003 thick
.0005 = 1/6 the thickness of a sheet of notebook paper
As long as the movement of the wristpin/rod/piston is smooth, and does not feel "gritty" when you move the rod on the wrist pin all will be fine.
If any debris is left from the smoothing, that didnt get flushed away, will proberly be about the same in size as what you would find in your engine oil when you change it at 3k miles.
The big thing is to make sure the oil galley holes in the crank are clean.
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