Did I get a bad piston ring from Kubota?

[PWH]

Installing a new piston in my Kubota L3010 this afternoon and ran into a major issue. When compressing the rings with my compressor tool before inserting the piston it in the cylinder I could see the top ring was oversize as the compression tool would not compress the top ring completely. Top piston ring appears to be oversized but other 2 rings appear to be correct. I removed the ring compressor tool and now the top ring is stuck in the piston. I guess I should have gapped the top ring but I've never had to do this on any of the kubota engines I've rebuilt in the past using kubota original parts. Piston and rings are standard size and kubota original parts.

Any ideas on how to get top ring unstuck without damaging piston?

 

[NorthwoodsLife]

That sucks!

My 2 cents...

I'd sent it or take it back to the dealer you ordered it from exactly as it is.... with wrong ring still in place.
That way they'll see the problem without you having to explain it to them.

Because they'll probably tell you it's the correct ring. But when installed it obviously is not the correct ring.

 

[MountainMeadows]

It could also be the ring groove on the piston not being machined correctly.

 

[Fedup]

I see this as just another example of why each and every part needs to be individually scrutinized before assembly any more, no matter what supplier you get engine parts from. You can't trust anything to correct without checking it first.

 

[William1]

Any time I install a new ring (or piston for that matter!), I check the end gap. To make sure they are not too tight OR... too loose. I do not care who is the manufacturer or reseller. If there is a spec, it gets checked.

 

[TheOldHokie]

Any ideas on how to get top ring unstuck without damaging piston?

A dental type pick and patience.

Dan

 

[lynnmor]

Is there no gap as it is stuck in the groove? If you have a gap, maybe pry it out from there. Is the ring too wide forming a press fit in the groove, if so the piston may have the groove sheared and now needs replaced.

 

[North Idaho Wolfman]

I'm betting you put the ring in upside down.
The to ring is a wedge.
And if you did you more than likely damaged both the ring and piston.

 

[GeoHorn]

What Wolf said…^^^^

…. and, before installing rings on ANY piston…. lubricate the cylinder-walls and push the rings into position in the cylinder…and measure the end-gaps for clearance. .005” is typical most engines, in my experience.

(one method to put the rings down into the cylinder is to put the ring inside the cyl…then using an upside-down piston…use it to push the rings down into position inside the cylinder. This method will assure that the rings are running in proper alignment and not “cocked”.

 

[dholt53]

Installing a new piston in my Kubota L3010 this afternoon and ran into a major issue. When compressing the rings with my compressor tool before inserting the piston it in the cylinder I could see the top ring was oversize as the compression tool would not compress the top ring completely. Top piston ring appears to be oversized but other 2 rings appear to be correct. I removed the ring compressor tool and now the top ring is stuck in the piston. I guess I should have gapped the top ring but I've never had to do this on any of the kubota engines I've rebuilt in the past using kubota original parts. Piston and rings are standard size and kubota original parts.

Any ideas on how to get top ring unstuck without damaging piston?

ring is up side down. Tap our ring with a soft punch

 

[Nicksacco]

If indeed the ring is correct and yet upside down, once you remove it from the piston, Measure the piston to ensure it is still the same size OD. Pressing in the ring may have caused the ring area of the piston to "grow" a bit.

Check the piston to be sure the metal between the rings hasn't been "sharpened" and the piston still goes down in the cylinder smoothly.

 

[PWH]

Thanks everyone for the info. Before I put the ring in I did examine it carefully for a manufacture mark close to the gap ends (as stated in the wsm) but could not find one. I also looked to see if the ring was tapered. Probably a screw up on my end then. The ring is in very tight with very little gap and protrudes out in one area so there is no way it would be going in the cylinder.

Here's a few shots of the stuck ring in the piston and the old piston. Will examine the old top ring and piston to see if the top groove is wedged.

 

[PWH]

What Wolf said…^^^^

…. and, before installing rings on ANY piston…. lubricate the cylinder-walls and push the rings into position in the cylinder…and measure the end-gaps for clearance. .005” is typical most engines, in my experience.

(one method to put the rings down into the cylinder is to put the ring inside the cyl…then using an upside-down piston…use it to push the rings down into position inside the cylinder. This method will assure that the rings are running in proper alignment and not “cocked”.

Great advice! I should have done this but since I've never had an issue with oem parts I got lazy! Lesson learned!

 

[PWH]

I'm betting you put the ring in upside down.
The to ring is a wedge.
And if you did you more than likely damaged both the ring and piston.

View attachment 122082

Thanks for the info Wolfman! Very helpful

 

[North Idaho Wolfman]

Pull the rings off that come off easy.
Put the piston in a pot of boiling water, you might get enough movement in the piston to allow the ring to release.
Same could be said if you throw it in a freezer, or much better pack it in dry ice, or even better liquid nitrogen.

 

[PWH]

Pull the rings off that come off easy.
Put the piston in a pot of boiling water, you might get enough movement in the piston to allow the ring to release.
Same could be said if you throw it in a freezer, or much better pack it in dry ice, or even better liquid nitrogen.

Well got the ring off with a small right angled pick inserted in the gap and applied a couple light taps. Ring sprung open fairly easily. You were totally right that I put it in upside down. Can't believe I missed the manufacturers mark as I've replaced pistons in the past and not made this mistake.

Now my question is would you use the piston and rings or is there a chance I damaged the top piston grove by forcing the ring in the wrong way? As well, the top ring's outer surface has some scratches on it from when I pulled it out of the compressor tool but I'm thinking that's not going to affect it seating properly.

Thanks again for all the help!

 

[North Idaho Wolfman]

Well got the ring off with a small right angled pick inserted in the gap and applied a couple light taps. Ring sprung open fairly easily. You were totally right that I put it in upside down. Can't believe I missed the manufacturers mark as I've replaced pistons in the past and not made this mistake.

Now my question is would you use the piston and rings or is there a chance I damaged the top piston grove by forcing the ring in the wrong way? As well, the top ring's outer surface has some scratches on it from when I pulled it out of the compressor tool but I'm thinking that's not going to affect it seating properly.

Thanks again for all the help!

I think you'll be fine to run both.

 

[PWH]

I think you'll be fine to run both.

Ok thanks!

 

[Yooper]

Well got the ring off with a small right angled pick inserted in the gap and applied a couple light taps. Ring sprung open fairly easily. You were totally right that I put it in upside down. Can't believe I missed the manufacturers mark as I've replaced pistons in the past and not made this mistake.

Now my question is would you use the piston and rings or is there a chance I damaged the top piston grove by forcing the ring in the wrong way? As well, the top ring's outer surface has some scratches on it from when I pulled it out of the compressor tool but I'm thinking that's not going to affect it seating properly.

Thanks again for all the help!

Thank you for posting this follow up! And thank you Wolfman for posting the piston profile diagram! Learned something new today.

 

[hagrid]

Tap our ring with a soft punch

Sounds like my high school cheerleader squad.