This is one I posted over on the festering evil forum a couple days ago with moderate replies. I wouldn't mind hearing from you guys on this, especially ya fellow builder guys.



Here's my original post:



"I'm pitching this out to you all who've assembled any motors using the Rotary Aviation o-ring kit w/ the TES (teflon-encapsulated silicone) inner o-rings. Have any of you have any issues with not only assembly due to the o-rings being slightly too skinny diameter-wise but also with random, intermittent symptoms that suggest an overheated motor even though the motor has no history of it?"



Some of my replies to others' responses:



"That's been my experience. Most of the motors I built between '03 and '06 use that o-ring set. The problems I had with their o-rings were the orange, inner water jacket ones. I'm getting odd reports from a few customers here and there that are exhibiting partial symptoms of overheating for absolutely no reason whatsoever. None of the motors have overheating or water-burning history yet they are showing some of these symptoms that would say otherwise, even though it's usually only some of the symptoms instead of all of them. I discontinued using this o-ring set in mid-late '06 and have since reverted back to stock as I am beginning to believe that these inner o-rings from that RA set are not a good choice to use, even if the material and construction of the o-ring is superior (my original motivation for using them in the first place). I am also curious of the technical aspect of using a round o-ring in a square-ring land."



Basically, I'm done with these things. I won't build another motor with them nor will I ever recommend them again. The last motor I built with them was I think around Aug or Sept time as I've since gone back to stock. I'm sick of the fitment trouble with them. What's taking a typical 3-6 hour assembly job is taking two days sometimes because of those o-rings. I'm also sick of having to deal with some of these engines that are exhibiting such odd symptoms of overheating even though these motors have absolutely zero reason to be doing that. The only consistent thing is those o-rings. Heck, even a buddy of mine, Mario, told me about how his car was spitting coolant out of the exhaust the other day after having let the thing sit for a week. It's blowing white smoke that smells like syrup yet it has never overheated once.



What do you guys think? Don't get me wrong; I am a fan of the teflon-encapsulated silicone idea, but I don't think the RA o-ring is the right way to go about it on our engines.



B

 

Found a couple of pictures of what I'm talkin' about.



Here's some from an engine I built in summer '04 that had one of those o-rings pop out of the groove and shear during assembly. It required me tearing nearly the whole thing down and replacing the ring. Two pictures show the sheared o-ring. The other pictures show my miserable attempts at "weighting" the o-ring down in place, forcing it to adhere to the shape of the iron's o-ring land. The sheared o-ring "event" occured after all this effort.



Wonderful.



B

 

I have yet to have a problem with them. To get around the fitment issue, I took a piece of 1/2" MDF, and cut it to the same size as the groove, and scewed it to another piece slightly larger. I usually keep o-ring kits on hand, and just leave them on that until I need to use the seals. They come out perfectly shaped every time, and drop right into the groove. Theyre even easier to install than the stock seals like that.



I could certainly see even a slightly damaged o-ring causing the overheating problems, and its very easy to damage the o-rings if theyre not pre-formed to the groove. Like I said, I have yet to have a problem since I have been using that board to form them to shape.

 

This is a bit of an ideological question I suppose, but nonetheless one I feel that's valid: Why in the world should we have to do this to o-rings that are already specifically and decidedly sold for engine use? What's going to happen to those of us that aren't as intuitive as you that just assume they're good and go for building the motor with the rings as-is? At best, it seems like a very bad way to sell a product IMO.



B

 

I agree, but think about it this way. The material engineering on those o-rings is solid. The problem is they arent engineered specifically for our application. While Im sure RA could spend a little time forming them to shape before selling them, it would add to the price. So from a business perspective, you could charge more for a superior product, or less for an imperfect one. Who is to say one is bad business, because in the end, both are profitable. And isnt that the point of business?





Heres wahat I use to form the o-rings:

 

I don't agree entirely. The purpose of business is to make a profit. That profit, for a business to survive in the long run, needs to be done reasonably and well. Part of that reasonable work needs to be quality control, not to mention good advertising. When I go to the RA website, for example, and check out their "13B O-Ring Kit", and see nothing else nor any warnings concerning having to do any extra work, I am fully expecting to spend my money on a kit that's tailoured specifically to the engine that doesn't require any extra "assembly" or "modification" on my part. That's part of my whole beef with this -- There's been so many times where I've purchased these o-rings kits that sometimes they fit just fine and yet sometimes they didn't, requiring some sort of trickery. So I rhetorically beg the question again, "why should I have to modify these o-rings (half of the time) to get them to fit? Why should I have to do any work at all when I've already spent my money on a product that wasn't advertised with any extra information regarding work on my part?" If they chose to "fix" these o-rings by "molding" them into the inner o-ring land and then raising the price, then it wouldn't be a fair thing to do IMO, as a consumer. It seems to me that if they're motivated to do a great job and sell a killer product, they ought to be conscious of this fact and build the o-ring right so it's sold and delivered exactly as it's advertised.



B

 

http://www.rotaryeng.net/O-rings-sizes-and...uct-6-30-06.txt



Thought this info was pretty much common knowledge.





http://www.rotaryeng.net/TEFLON_COATED_O_RINGS_IMG4.GIF

http://www.rotaryeng.net/O_RING_STORAGE_BOARD.JPG



Having custom made to order rings is an expensive proposition,,,



ask me how I know

 

I know what you mean about the fitment issues, they tend to pop out at times. Before I lower each plate I check them to make sure they are ok and use a lot of frozen vaseline. If I use vaseline that is room temp they seem to pop out more. I leave the vaseline in the fridge for a while and ONLY apply the vaseline to the irons to hold them in place just before I close them together. That works for me.



I just started building motors for others (no porting) and have used them with no issues yet. I also have used them in my motor for a few years and reused them for a few rebuilds with no issues.



Anthony

 

True bolt-and-go components in the aftermarket are rare beasts. Almost everything we do involves some modification, tweaking, or fabrication in order to make it fit properly. This seems to go double for so-called "kits", too.



Even the Mazda factory seals aren't formed-to-shape, and require a bit of fiddling to get them to stay seated in their grooves.

 

Fiddling is one thing heretic, but having to use a wooden template to mold an o-ring that doesn't otherwise fit or questionably does is something entirely different. It's jacked up three of my builds because those o-rings don't otherwise fit some of the time. Having to do modifications is fine; I've been doing that for 10 years now, but good grief -- when you buy o-rings per an "O-ring kit" you'd expect them atleast be basically reliable, right? They ought to be able to fit the stinkin' engine they're designed for and not give these kinds of annoying problems over and over, right? Not to mention these strange, overheating-like issues they seem to show....



B