2210 Piston Oil Ring

[Tole]

Installing my oil ring on the piston, I find the gap in the piston the ring sits in is so tight over the pin that the oil ring would need forced into the groove. Physically the piston looks fine. The whole piston is clean and nothing is in any of the grooves. Measuring the ring groove, over the pin, the gap is .0035 smaller then the rest of the groove. I don't get how it could be anything but a defect, the other piston was not this way.

Should I be replacing this piston?

I guess if I have to ask, I already know the answer. Seems like such a waste.

 

[winston1]

Is this a new piston? How long is the area that is .0035 smaller? Is the piston pin to piston within specs? If an old piston it would almost seem that piston might have taken a knock from the top and maybe the pin pushed that aluminum up a little. Pure speculation on my part and I would think you do need to replace the piston.

 

[Tole]

It is the same piston that came out. I did not notice the oil ring sticking when I took it out. If I roll the ring around the hole, its only immediately above the left side of the hole, just enough that rolling it around will bring it all the way out and then drop it right back in after maybe .1 inch in length. The piston does not show any damage on the top, however the crank broke directly in the middle of the journal under this rod which is what got me here. The specs were spot on with the pin, I did replace the rod due to a minor skuff on the side where it rubbed the broke crank.

I guess while I'm here and to be safe, i'll just order a new piston.

 

[winston1]

I think you would be wise to do that. A stuck oil ring wouldn't be good.

 

[clemsonfor]

I can't even understand what is going on here. I'm having trouble understanding where the gap is smaller and which direction?

 

[ruffdog]

I can't even understand what is going on here. I'm having trouble understanding where the gap is smaller and which direction?

I'm thinking that the ring groove is narrow near the wrist pin.

 

[winston1]

I'm thinking that the ring groove is narrow near the wrist pin.

Right on! :thumbsup: