Shop wants to put in new rings in high mileage engine

Hi Is there any scenario where putting new rings in a high mileage engine would work? From what I understand the taper on a high mileage engine is most likely so high that the new rings will not seal properly. What would the result be? Poor running engine due to blowby? Someone even suggested that reusing old rings are better. Has anyone put in new rings with success? Was this OK to do on aircooled engines? Maybe the shop is applying aircooled knowledge.

I read a lot that new rings don't work in a old cylinder because of the old cylinder liners go oval. Don't believe you can hone out ovality.

Why replace the current rings?

That won't end well... The Aircooled engines could do this with good results, but the Porsche Aircooled engine, and the M9X aren't even on the same planet in regard to this. A high mileage M9X will have cylinders that have excessive taper, and ovality, as a best case scenario, in most cases. New rings hate this.

The ONLY possible scenario , is if the builder really was a ninja,, and had the right measuring equipment to profile the bores and they came out perfect. This sounds like a bait and switch, get your motor apart and "oh my goodness its got x,y,z wrong with it.. " Now we need a full rebuild it will only cost 19K.. LN & Hartech & Porsche, so far the only sources I've found for re manufactured engine cases.. (That seem like they have trust... ) The minimum you'll need is re-manufactured cases and all the rotating assembly at least gone through. Anything less your just short-sheeting the bed..

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That is a good question! Could it be they only want to change an oil ring or something like That? It's bit annoying, really like the shop. Seems like they are great with aircooled but less experienced with the water cooled. So what would happen? They would gap the rings to satisfy the diameter of the cylinder in the top? But once the piston moves downward the ring will squeeze to much? Or will they just wiggle and break? My plan was to not touch the bores/rings, little surprised by their statement. Thanks everyone

Basically the original rings wear to fit the bore and the bore wears to fit the rings... The Air cooled Porsches are like 2 stroke dirt bike engines,, you do rings if you open them, they are cheap and the air cooled jugs are stout,, a light hone and a new set of rigs are darn near a rebuild, and the old nikasil jugs would wear out 3 to 4 sets of pistons and rings before they needed touched if you serviced the engine.. Water cooled porsches are the modern water cooled dirt bike, The stock 996/997 is a Alusil bore, which is WAY thinner and not nearly as tough. Many modern thumper bike motors you get 1 run and when they wear out you buy a new top end.. Or you sleeve the cylinder or have it re-coated,, Sounding familiar?? LOL Just to compare, my 2006 KTM 950 V twin costs about $7000 to do a full rebuild.. So its on par with a FSI engine rebuild if you figure it by the liter..

I know what I would do if it were mine, measure the ovality, if it is more than .003 in, take it to a local machine shop willing to devise a special "jack-screw" to jack the cylinder back to round then install an aluminum support ring at the top of the cylinder to hold it round. This will also keep the cylinder from ovaling and cracking, or "D" chunking in the future. Then you could install new piston rings successfully. Also need to increase the dept of the cooling slots the required amount equal to the thickness of the support rings.. Hartech has had much success doing this and charges 60 bucks per cylinder. Over here may cost more especially for a first-timer machine shop, with having to design a special "jack-screw" to fit the cylinder. But some machine shops love a good challenge once in a while and something new.

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I had a YZ125, it's the best. Cost $1500 and sounds and feels amazing. Cost me an ACL but worth it, I guess you shouldn't start doing Motorcross in your 30s. You should stop motocross when you turn 18 They should make 2 stroke 996s... I think that is too much for my local machine shop. They say that they have seen it all but I think that is they seen it all in regards to different chevy blocks. It's an old school place. Also not sure if the rings need to be replaced, from what I know there is not a lack of compression. Any change they can break from age?

That's never heard of Lokasil cylinders....

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Alusil? I think you're getting the M96/M97 mixed up with the 9A1.

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Yep, or the Cayenne... Or they don't know the difference~

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I have found machine shops can be odd places at times, they go a little nutty chasing thousandths of an inch all day every day, and sometimes ten thousandths of an inch, and it's a moving target with temps ect. It's always best to know exactly what you want, and be able to convey that to them, at the same time be willing to listen to their advice if they offer it. And it course take full responsibility for the outcome, just ask for their precision and workmanship, equipment and time.

Maybe we should back this up a bit: Why is engine disassembly being considered at all? I'm assuming the ring idea is a "while we're in there" idea?

Alusil, Lokasil, no matter (as far as this question is concerned), I cannot think of any bore material that ends in "sil" that you can simply throw a fresh set of rings in.

I'm curious why new rings are on the table at all... Is there an issue at play?

Really, get some data. Compression and leak down aren�t the best for H6 engines, but at least something. I was told by my engine builder you can�t measure out of round unless everything is torqued down.

The IMS chain guide might be worn, so while disassembling the engine the builder wanted to fix some "while you are in there". This includes bearings and rings. I think this is a default move on the aircooled engines, but not so sure it's the best move on watercooled. What about main and rod bearings?

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OOPS,, yes ,, Senior moment..

Hartech in the Uk car hone a standard bore and fit a support ring on the top, new rings can then be fitted , did this with mine , depends on a pre evaluation process of how much ovality you have and wether it can be machines out without making the bore too big !