Where in the block can a ring hide?

[One1]

My 657 ate a ring and I have cleaned out the bottom end with suction and flushed it however I have concerns it's more likely that it blew the ring pieces out the exhaust. I have found no trace of the upper ring anywhere. I can see down through the crankshaft to the bottom there's no remaining gas or oil and flushing it doesn't produce anything. What's the likelihood that any part of that ring could still be down there how much space is there? I don't think it could go further than under the crank on that side due to the crank bearings?

The attached pic is a reference (not mine). I don't see how the ring could be anywhere else if no pieces are under the crank that the issue occurred. Seems most likely the entire top ring, in however many pieces it went out, blew out clean (wasn't found anywhere in the expansion, muffler, exhaust tube).

 

[etemplet]

Oddly enough I have the same thoughts about a ring and piston parts on a 657 I am working on. Upper ring failed on the PTO side with piston top broken. Cylinder Bore looks great with a slight bit of damage to the head, nothing serious at all. I guess everything went out the exhaust port. I'm gonna do lots of looking though.

 

[mikidymac]

Like asking will I win the lottery. There is a 50/50 chance it’s in the bottom. Either split the cases and be 100% sure or roll the dice.

 

[One1]

Well that's the question..... Can it be anywhere other than in the chamber under the piston that failed.... The bearings on the crank seem to say no, are there any passages?

 

[mikidymac]

There can be pieces in the crank and rod bearings as they are open to the crankcase.

 

[etemplet]

My 657 ate a ring and I have cleaned out the bottom end with suction and flushed it however I have concerns it's more likely that it blew the ring pieces out the exhaust. I have found no trace of the upper ring anywhere. I can see down through the crankshaft to the bottom there's no remaining gas or oil and flushing it doesn't produce anything. What's the likelihood that any part of that ring could still be down there how much space is there? I don't think it could go further than under the crank on that side due to the crank bearings?

The attached pic is a reference (not mine). I don't see how the ring could be anywhere else if no pieces are under the crank that the issue occurred. Seems most likely the entire top ring, in however many pieces it went out, blew out clean (wasn't found anywhere in the expansion, muffler, exhaust tube).

 

[etemplet]

I'm not rolling the dice, I spent a couple of hours looking around for pieces. The whole compression ring is gone on the PTO side and a half penny size piece out of the top of the piston. The top ring is in place. I found a couple little pieces in the bottom end. Like One1 I spent a lot of time cleaning blowing air, got my camera in there and found absolutely nothing. I also found damage to the Mag cylinder rings... half the compression ring was gone... no sign of anything. I cleaned it all up checked it a dozen times are more and checked again. This baby is going back together.
Hey One1 I'll post some pictures of the pistons tomorrow. I just finished honing the cylinders. I'm always do a lot of prep, port chamfer, stoning the gasket surfaces, and clean clean clean.

On a side note, the mag cylinder still had 150 pounds of pressure. I am convinced that checking compression on these engines does not tell there condition.

 

[Sportster-2001-951C-Stock]

Broken rings and bits of metal dust are probably washed into the rod bearings waiting to sieze them in a short time.

 

[Sportster-2001-951C-Stock]

I am convinced that checking compression on these engines does not tell there condition.

I promise you that if blow-by is too much, the oil film on the cylinder sleeve will fail.

 

[Sportster-2001-951C-Stock]

half the compression ring was gone...

Sounds like the ring end may have snagged in the cylinder port. Look and see if the ring-end locating pin in the piston is missing or sheered.

You can have great compression up until a ring snags in a cylinder port.

 

[Sportster-2001-951C-Stock]

Wrist pin clips have been found as far away as the intake manifold and flame arrestor also spinning around in the RV. I've found plenty of broken rings in exhaust manifolds as well.

 

[etemplet]

Sounds like the ring end may have snagged in the cylinder port. Look and see if the ring-end locating pin in the piston is missing or sheered.

You can have great compression up until a ring snags in a cylinder port.

Even AFTER. The Mag cylinder still had 150 pounds with 1/2 the second ring in place which proves the top ring was doing it's job.

 

[etemplet]

Sounds like the ring end may have snagged in the cylinder port. Look and see if the ring-end locating pin in the piston is missing or sheered.

You can have great compression up until a ring snags in a cylinder port.

First thing I checked was the cylinder bore edge of the ports. Whoever bored the cylinders did not champfer the edges. I take a bit of time with each cylinder to make sure that isn't the case when I bore cylinders.

 

[Sportster-2001-951C-Stock]

Yep, I've seen instances where the ports weren't properly chamfered (radiused edges) and ring snagging was occurring. Sometimes it makes sense to yank the head if there's any doubt (sometimes you can even feel it by turning the crank) and look for slight scoring (such as rapid loss of honing marks) around the port edges b/c the oil is wiped off the ring as it passes across the port.

In the case of the broken/missing ring, this reminds me of the couple engines we once built and left the 2nd ring out, looking for a performance gain. LOL, I don't recall noting anything of significance but those engines were run that way for as long as I can recall and were likely sold that way.

Man, you were lucky (IMO) when the ring snagged it didn't damage the ring land and pinch the other ring.

But anyway, as you noted, it's MUY IMPORTANTE the ports are dressed with the proper radius and machinists should know this.

 

[One1]

All i have is a block in. No top end, no intake or exhaust. I looked WELL before asking. Just don't want to needlessly upset the bearing and seal on the shaft if there is no way anything could get past the crank bearings to the other chamber. You can't flush them any better in than out and vice versa, so....... Long as a piece can't get from the offending chamber to the other areas then i believe it's ready to be put back together.

 

[One1]

Even AFTER. The Mag cylinder still had 150 pounds with 1/2 the second ring in place which proves the top ring was doing it's job.

Lost my upper ring on the exhaust port and it dropped by half immediately. Wouldn't start.

 

[mikidymac]

Well, you keep asking and we keep telling you it can get into the crank ball bearings and the rod big end needle bearings. Run it if you want but we are just going to keep telling you what you should do and split the cases. Also a great time to replace the old outer crank seals.

 

[etemplet]

All i have is a block in. No top end, no intake or exhaust. I looked WELL before asking. Just don't want to needlessly upset the bearing and seal on the shaft if there is no way anything could get past the crank bearings to the other chamber. You can't flush them any better in than out and vice versa, so....... Long as a piece can't get from the offending chamber to the other areas then i believe it's ready to be put back together.

I agree. You just have to made a decision based on what you see and feel.