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quantico

re-use rings ? wrist pin retaining springs ???

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quantico
I am rebuilding a kohler m-18-S for my 917-H and the kohler manual says not to re-use the rings or wrist pin retaining springs ... My question is why do they recommend not re-using those parts. The engine threw a rod due to gas in the oil. The engine is only three years old, so I am curious if I can re-use the parts or not. I don't know why kohler insists that those parts not get re-used. I purchased spare sets of rings and even the pison wrist pin retaining springs.. I have the parts here if I need them, but would reuse the parts if they are ok.. The rings look great and I have not yet measured the ring end gap.. but I bet it's fine.. Please tell me what the deal is ... thanks

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Al
Hi, I never reuse rings that have been run, and always replace the retaining rings. Have had lock ring fail in a Harley-Davidson golf car over 25 years ago. Wrist pin came out and cost me a cylinder. Never Again. I also almost never re-ring an engine. If the cyl measures over 003 wear I rebore it even on our used tractors. I want people to know that when I do an engine, it will be right. I would ask why skimp 50.00 on this project now? Then have the possibility of having to tear it down in a year and spend it then. You then have to buy another 50.00 gasket set and have to do all of that labor over? AL Eden

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quantico
I am not trying to skimp.. I can put the new parts in. I have them in hand allready. My question is how three year old rings that look brand new in a cylinder (that measures like new) can fail ? do they fail to seat a second time ??? also how can the springs that retain the wrist pins fall out when they are correctly in their grooves and seem to have great spring tension ? I am trying to figure out why you can re-use a piston but not the rings. It would always be better to replace the crank and connecting rods and pistons and rings and install them into new cylinder jugs with all new valves... but that is not required in this engine. The wear does not justify it. I am trying to learn why the rings should not be reused.... why the valve springs are re-useable , but not the wrist pin retaining springs .

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UCD
You can re-use them it is your engine and you are the one paying the bills, but that is not the thing to do. Rings are a high wear item they seat in in a pattern and should not be re-used. Why cause yourself unforeseen problems down the road. Murphy's law anything that can go wrong will go wrong. Anything imposable to go wrong will go wrong. Some parts in an engine can be re-used with out a problem, rings are not one of them.

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PGL
I would expect the reason people don't reuse rings is because, as Al indicated, their experience has been that there is more likelihood of them failing prematurely. Why? In part just the strain on them from removing and replacing an extra time, maybe a little bend where there wasn't one before, who knows? It's probably just the collected wisdom of mechanics passed on to others. Maybe your newer rings and little use would overcome the problems, but without convincing evidence, why take the chance? Even if one or two people have done it without a problem, I would still put in new.

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Al
Hi, On the engine I had the lock rings had a little wear groove where the wrist pin had contacted them in use. I would suspect that that contributed to the failure. The lock rings are so cheap I don't question Kohler's recommendation. All I know is I bored this golf car and put a new piston in and the new lock rings that came with the piston were missing and I just used the ones from the old piston and about 2 months later if came back with no compression and when I pulled the head there were 2 big grooves in the cylinder where the pin had come out. I didn't think they looked very bad, but did see the shiny ring where the wrist pin had rubbed them when they were in the old piston. I have never reused one since. Keep in mind that in removing them they often get "compressed" enough to get a pliers on them to pull them out and re-compressed to reinstall them. As for the rings, the finish surface on new rings that seats with the crosshatch in the cylinder is gone when they seat. Reinstalling them puts a different surface finish against the cylinder to re-seat. My thoughts, they are free, keep this in mind when you evaluate these comments. Al Eden

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olcowhand
I don't mean to go against anyone's grain here, but I have reused rings many times & never had a problem. BUT when I take the piston out, I scribe tiny marks on top of piston indicating each ring's end gap position on the piston. Cylinders are never perfect circle, so this way they go right back in as they were. Even if rings aren't put back in exact position as they were, they will likely "migrate" back to where they were. There is no reseating when done this way, it's all just as it was. Now if you hone the cylinder, then new rings are needed. I reuse the clips also if clips have no wear. But I do replace if any have wear from the pin as mentioned. I do however expand the clip a bit to guarantee a good spring-tight fit. I've done this on probably 50 engines or so & never had a problem. But I can't guarantee success if you do it the same way as I did. Engines have a way of doing what they want sometimes.

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quantico
I used all new parts and did the rebuild with them. I have the engine back together and it started and ran several minutes and sounds great. I am having a carb or fuel / fuel mixture issue as the engine will stall unless I play with the choke and make the mixture richer. I have not had time to mess with the fuel issue, but am really happy that the engine starts and seems to be happy. I took apart the fuel pump and the carb float bowl to clean and look for the problem on where fuel was getting into the oil on this engine. I may have missed a problem or created one. I have not adjusted the screws in the carb, and seem to have the cables back in place correctly based on my extensive tear apart pictures. The engine stalls unless I pull the choke on.... or if I try to rapidly open the throttle...

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