Newbie dropped forged piston
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On The Tree
Joined: Sep 2010
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From: Lima oh
Newbie dropped forged piston 
Dropped a piston on the floor , during an attempt to pull the spiral circlips to flip the con rod. Due to my
piston valve reliefs being incorrectly oriented.
here’s photos of the damage. I lightly sanded the inner bottom skirt and top where dinging occurred.
I can run my fingernail 3/4” above the bottom and catch my nail on the small dings.
im leaning toward biting a fat bullet and ordering a replacement. Again I’m coming to terms that assembling
A motor from the bottom end up is a bit of a learning curve. Just looking for anyones .02.
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On The Tree
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From: Lima oh
Just got off the phone and forwarded this photo to the manufacturer’s sales supervisor
I’m in shock and pleasantly surprised that he advised myself to take penetrant and 400
grit and take down the high spots just enough and send it. Advised me it would be fine.
This logic somewhat makes sense since the rings are contacting the cylinder wall. not the piston
itself. As for the coating he said it was a xylene. Not here to start an argument or say that years
of experience to those people chiming in here is wrong at all. This is merely my experience today.
I’m in shock and pleasantly surprised that he advised myself to take penetrant and 400
grit and take down the high spots just enough and send it. Advised me it would be fine.
This logic somewhat makes sense since the rings are contacting the cylinder wall. not the piston
itself. As for the coating he said it was a xylene. Not here to start an argument or say that years
of experience to those people chiming in here is wrong at all. This is merely my experience today.
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From: Nebraska, The Good Life
Well, you would be wrong about that. The skirt of the piston is what keeps the piston square in the cylinder. Now, technically there should always be a film of oil between the piston skirt and the cylinder wall, but the same goes for the rings. Anyway, point being, the rings are NOT the only part to touch the cylinder walls.
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On The Tree
Joined: Sep 2010
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From: Lima oh
Well, you would be wrong about that. The skirt of the piston is what keeps the piston square in the cylinder. Now, technically there should always be a film of oil between the piston skirt and the cylinder wall, but the same goes for the rings. Anyway, point being, the rings are NOT the only part to touch the cylinder walls.
that doesn’t have a piston skirt ? In that case would those rings be the only thing in that situation keeping the piston square?
Last edited by thedetroitkid; Jan 17, 2022 at 03:05 PM. Reason: Na
I stand corrected- I’m going on a tangent here but I do love learning new things… in this matter how would One go about explaining an f1 style piston or even crf450 dirt bike piston
that doesn’t have a piston skirt ? In that case would those rings be the only thing in that situation keeping the piston square?
that doesn’t have a piston skirt ? In that case would those rings be the only thing in that situation keeping the piston square?
If you are comfortable with what the sales manager said, then definitely run it as is.
Making an informed decision and being comfortable with the possible outcome is about the best one can do.
Me, I'd replace it regardless of what the sales manager said for my own peace of mind.
Making an informed decision and being comfortable with the possible outcome is about the best one can do.
Me, I'd replace it regardless of what the sales manager said for my own peace of mind.
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From: Texas
Guys, it's just a piston that hit the floor from three feet - maybe four.
How hard could it have hit the ground? If the piston is junk with that kind of impact, it must be a pretty shitty piston.
How much force does a piston see at 6K rpm? Probably a lot more than that one saw.
I'd sand down the high spots and send it.
O/P, what brand/ part number of piston is this?
How hard could it have hit the ground? If the piston is junk with that kind of impact, it must be a pretty shitty piston.
How much force does a piston see at 6K rpm? Probably a lot more than that one saw.
I'd sand down the high spots and send it.
O/P, what brand/ part number of piston is this?
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From: PDX-OR-USA
That's spot that took the scuffing is the part of the skirt that has the most contact with the cylinder..
How much is a replacement? vs a whole engine tear-down, cleaning it up would work, life
expectancy after losing the coating probably a minor hit ..
Post doesn't say how hard this engine is going to run..
If I was going to use it, I'd work real hard with a fine sanding block to get that area smooth taking as little coating off as possible.
I'd order new as long as it wasn't some 400 dollar custom one.
How much is a replacement? vs a whole engine tear-down, cleaning it up would work, life
expectancy after losing the coating probably a minor hit ..
Post doesn't say how hard this engine is going to run..
If I was going to use it, I'd work real hard with a fine sanding block to get that area smooth taking as little coating off as possible.
I'd order new as long as it wasn't some 400 dollar custom one.
Thread Starter
On The Tree
Joined: Sep 2010
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From: Lima oh
spent about 20 minutes with wd40 and 400 grit taking off the high spots.
This motor will see long term use and abuse . I realize the predicament is less than ideal.
although what started as a budget build turned into a lot more in terms of everything.
including this build seeing a move into a new house and myself being laid off at them moment.
with that being said if the manufacturer is comfortable and will stand by their product.
it gives me a good feeling even if no warranty is expressed or implied.
I should’ve taken an after photo before I put it in the block.
sad part is I’m conflicted as to whether I should send it or not after the 1500 I spent at the machine shop. I may just call the good people in eastern Kentucky I usually deal with and
see if they can have a match made for this application. As others have said I’ll always wonder if it will be ok.
Last edited by thedetroitkid; Jan 18, 2022 at 07:22 AM. Reason: Indecisiveness
Just got off the phone and forwarded this photo to the manufacturer’s sales supervisor
I’m in shock and pleasantly surprised that he advised myself to take penetrant and 400
grit and take down the high spots just enough and send it. Advised me it would be fine.
This logic somewhat makes sense since the rings are contacting the cylinder wall. not the piston
itself. As for the coating he said it was a xylene. Not here to start an argument or say that years
of experience to those people chiming in here is wrong at all. This is merely my experience today.
I’m in shock and pleasantly surprised that he advised myself to take penetrant and 400
grit and take down the high spots just enough and send it. Advised me it would be fine.
This logic somewhat makes sense since the rings are contacting the cylinder wall. not the piston
itself. As for the coating he said it was a xylene. Not here to start an argument or say that years
of experience to those people chiming in here is wrong at all. This is merely my experience today.
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From: St. Louis
30k miles ago when I put my 2001 LQ4 that I had bored 0.065" over together, my Silvo-Lite LS3 pistons arrived in a box that looked to have been opened at some point and one of the pistons had a big long scratch all the way down and all the way through the middle of the coating on one side of the skirts. I made sure to install it with the scratch facing up towards the middle of the block because I would assume that more wear occurs on the other side of the piston facing down. I've been driving it every day since with not a care in the world.
I've seen many internal components reinstalled in the lower end of engines in far worse condition than what you have with no problem at all. You are more likely to have a bearing failure due to overly tight clearances of new parts or improperly torqued fasteners than you are likely to have any trouble with that piston.
I've seen many internal components reinstalled in the lower end of engines in far worse condition than what you have with no problem at all. You are more likely to have a bearing failure due to overly tight clearances of new parts or improperly torqued fasteners than you are likely to have any trouble with that piston.
30k miles ago when I put my 2001 LQ4 that I had bored 0.065" over together, my Silvo-Lite LS3 pistons arrived in a box that looked to have been opened at some point and one of the pistons had a big long scratch all the way down and all the way through the middle of the coating on one side of the skirts. I made sure to install it with the scratch facing up towards the middle of the block because I would assume that more wear occurs on the other side of the piston facing down. I've been driving it every day since with not a care in the world.
I've seen many internal components reinstalled in the lower end of engines in far worse condition than what you have with no problem at all. You are more likely to have a bearing failure due to overly tight clearances of new parts or improperly torqued fasteners than you are likely to have any trouble with that piston.
I've seen many internal components reinstalled in the lower end of engines in far worse condition than what you have with no problem at all. You are more likely to have a bearing failure due to overly tight clearances of new parts or improperly torqued fasteners than you are likely to have any trouble with that piston.
In full skirt pistons, as these, it doesn't really matter since each side is equal, but they are cam ground and need to expand correctly. Attention should be paid to ring clocking. No ring gaps on the thrust side and no ring gaps over the wrist pin. This applies to the top two rings. The oil ring gaps can be placed anywhere, and ring gaps of any type should not line up with each other.