 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
budyerly@msn.com
Joined: 05 Oct 2019
Posts: 282
Location: Florida USA
|
 Posted: Sat Jan 06, 2024 7:28 am Post subject: Slight exhaust leak at cylinder head manifold joint |
 |
|
I found simply lapping the exhaust into the head cured the issues with the exhaust leaks at the cylinder head. Attention to detail is essential as I covered in my troubleshooting document.
The exhaust leak issues were normally with the 912S. The development woes of the 912S and its shaking, kickback, harmonic problems and cracking of the block were well covered up (probably a poor choice of words, more like "development issues") and many individual owners suffered (and still do) as Rotax blamed propellors, fuel, carb balancing etc. rather than just fixing the engine. By 2005 Rotax silently (in my opinion again) fixed most of these issues and after reinforcing the block, changing timing, carb mixture and stronger starters, we now have a well reinforced and timed 912S being produced. Those soldiering on with the older 912S engines have had to rebuild or replace the short block, gearbox, sprag clutch and other issues. The newer 912S is still not perfect but is an acceptable engine in my opinion as Rotax did address nearly all the original issues. I'm still not a fan of the 912iS or the big bores so don't ask . Time will tell on that. The 912 and 914 do not have near head leak issues as the 912S (pre-2006) but are not full proof either. Early models of the 912 and 914 had their issues also.
Lapping of the exhaust down pipe to the head has to be done at the angle and orientation the final fit will be, so alignment marking is essential as is patience holding pressure and slightly rotating the downpipe during the lapping process. It helps to have strong wrists or a helper to push while the other pushes and pulls on the downpipe. We used valve lapping compound at Custom Flight, and in about 20 minutes of work we had a good fit curing the leak around the offending conical exhaust fittings used on most of the 912S exhausts supplied for the Europa. I found the lapping method to be superior to trying copper or asbestos exhaust gaskets. Just make it fit properly! Aluminum is soft and easily "machined by hand" with the lapping compound.
The large cone to cylinder mating surface is ideal for lapping. Some have issues with the studs coming off with the nut. Remove the corroded nut, clean the stud or get a new one, and Loctite the stud back in and allow to cure. (Yes, the Loctite will fail with heat, but it will allow fitting and proper torque during cold installation.) PUT ON NEW NUTS as they are worth it. Don't be cheap or too quick to try Band-Aids as Aera 51 commented.
The muffler ball joints on the muffler originally did not have a proper seal either. I had to use exhaust sealing paste on the older CKT mufflers as a Band-Aid (pre 2010). Later Robin at CKT redesigned his downpipe to muffler joint and I find the new exhaust to be nearly full proof as the cup and ball seal works very well, especially with a little exhaust paste. CKT also found that the exhaust springs were best to be made from stainless spring material and they did extensive work on the cause of spring failure as well as securing the tooling needed for smooth, nick free spring manufacture which greatly improved the spring life. Hence you see nearly all the LSA aircraft using his exhaust or a copy. I know that motorcycle springs are cheaper, but they also do not have proper hooks in most cases. Again, don't be cheap, even motorcycles have issues and quality springs are not used due to cost. If they cost more, they don't sell but they last longer. Flying is not cheap unless you like a lot of downtime or excitement in flight. As my old friend Walter Hudson said: You know what keeps an airplane airborne, MONEY. It costs time and or money to fly a well maintained airplane.
Personally, I don't like springs on exhaust joints, so I also run .041 safety wire through my springs to the hooks to assure a broken spring did not become a FOD hazard. Plus, the exhaust stays together if a spring corrodes or fails because you chose cheap steel springs. To prevent spring harmonic resonation on the 912S I also run a thick bead of high temp silicone down one side of the spring which dampens the vibration increasing spring life.
Note: Any 912S maintainer should change all the springs at the 5-year point in my opinion. The springs will be heat cycled many times by then, and although looking OK, will eventually fail. Corroded springs should be replaced period.
Finally, exhaust manifolds and mufflers are not forever pieces of equipment. They endure extreme heat, vibration and are often abused with poor mounting on any internal combustion engine. Inspect your exhaust often and repair properly as an ill-fitting exhaust not only leaks, but it also causes harmonics of its own that contribute to fatigue around the heads. It is money in the bank if you have an original troublesome exhaust to simply "drop a thou" and replace the exhaust. (Engines don't last forever either. If your engine is excessively shaky, consider a short or long block overhaul if it is one of the early 912S engines. Maybe even a new replacement as even engines at or near 1000 hours are due serious maintenance, just like those dinosaur Lycoming and Continentals.)
My "Rotax Engine Troubleshooting and Maintenance from Experience" paper is still on the Europa Club website and my website (www.customflightcreations.com). It was updated last in November of 2021 and is still current. It has many of my maintenance techniques over the last 20 plus years maintaining the Rotax, including the exhaust.
Just my thoughts,
Bud Yerly
Custom Flight Creations
--
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
 |
peterz(at)zutrasoft.com
Guest
|
| Posted: Sat Jan 06, 2024 8:07 am Post subject: Slight exhaust leak at cylinder head manifold joint |
|
|
Great advice Bud!
I’d add two points:
1) sample size = 1, the copper gaskets are effective and durable, even with badly pitted heads unable to be rectified by lapping.
2) again, sample size = 1, my ULS (read high compression) classic with the factory approved heavy (measured 5300 rotational mass at the upper region of the rotax spec limit) 3blade fixed pitch non tapered warp drive prop, combined with low throttle & lower rpm cruising (underdamped lightly loaded blades), will set up gearbox dog resonances (as measured in flight with the smart avionics balancer isolating to the rotational axis and measuring in all three) which will ultimately pocket the dogs (amplifying the issue), and damage many engine attached components - and cracking exhausts ad nauseam. Blaming the engine/timing/start etc might be incorrect.
Yes, i am also running the smoothly sweet ignitech’s (start at ATDC), and a lithium battery with small starter - both installed prior to swapping in my super light e-prop (read no cruise resonances).
Cheers,
PeteZ
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
n7188u
Joined: 15 Nov 2015
Posts: 395
|
| Posted: Sun Jan 07, 2024 4:20 am Post subject: Re: Slight exhaust leak at cylinder head manifold joint |
|
|
Thank you Bud and Peter,
I cleaned the port yesterday and it is intact (shinny like when new) so for now I just applied some high temp paste (bandaid) since I really want to fly a little and I don’t think the problem is serious enough to be causing immediate damage.
On the mean time will read Buds procedure for lapping and will prepare to do that if the problem persists. I think lapping is indeed the best long term solution of the port surface is not damaged.
And thanks for the gasket info Peter. I will keep it on file in case I need something like that in the future.
I guess the main concern now is how to maintain the system with CKT gone but I am fairly optimistic that we will find ways. And hopefully the Europa Club together with Europa will find replacements for the most common serviceable items like springs.
It is my understanding the CKT mufflers are quite popular in the light aircraft world so hopefully either someone will take over that operation or parts will be available to allow existing muffler repairs shops to service our systems.
Chris
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
budyerly@msn.com
Joined: 05 Oct 2019
Posts: 282
Location: Florida USA
|
| Posted: Sun Jan 07, 2024 5:46 am Post subject: Slight exhaust leak at cylinder head manifold joint |
|
|
Chris:
Re: - CKT no longer in business!!! That is a shame. Shows you how much we 914 owners don’t follow up on the latest suppliers. We are all getting older and competition from “Cheap Chinese is getting to be more than a nuisance for suppliers, plus small airplane business is not a money maker, government regulations are a pain to work around unless you pay a politician, so folks don’t want to buy or continue these small plane supply businesses, hence our suppliers dry up.
- On your comment: “I just applied some high temp paste (bandaid) since I really want to fly a little and I don’t think the problem is serious enough to be causing immediate damage.” The weather is crappy now. Exhaust leaks are not minor in my opinion. I suggest you fix it, as little problems become bigger problems. A little time now saves a lot later on. (A stitch in time saves nine eh?)
Keep plugging away. You are making a very nice airplane even better.
Bud Yerly
--
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
n7188u
Joined: 15 Nov 2015
Posts: 395
|
| Posted: Sun Jan 07, 2024 7:04 am Post subject: Re: Slight exhaust leak at cylinder head manifold joint |
|
|
Hi Bud,
Thanks for your reply.
First on the CKT thing yes it is very sad. But your comments about why are right on. I am personally facing a similar situation as a product development Engineer for a big medical device company were things are so business oriented that it’s becoming more and more difficult for us Engineers to do an adequate job. To the point I have decided to go into early retirement this year and find something else to do. BTW, what is happening with Boeing is a good example of the consequences of what I see at work every day.
Anyway, setting that aside let’s hope someone picks up the CKT baton and provides support to these great components.
Regarding my exhaust leak, rest assured I am not going to sit on this. I am not the type to ignore issues, but I generally like to do my research and be prepared before jumping into the fix. My plan is to read up on your procedure, get what I need and do it. But this morning I was able to go for a short flight and have some fun (spending 8 month grounded to paint the airplane requires some compensation at the end  )
Chris
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
budyerly@msn.com
Joined: 05 Oct 2019
Posts: 282
Location: Florida USA
|
| Posted: Sun Jan 07, 2024 7:38 am Post subject: Slight exhaust leak at cylinder head manifold joint |
|
|
Chris,
I have small 3D printers and use a CAD program and draw up and produce my items for the shop, woodworking, home, and auto as the problem with engineers is we think we can do it better.
Hence, I have stopped going to manufacturers, machine tool and die shops and sourcing those folks to do some of the work. Hence they are all just giving up and closing the doors as the competition for "one offs" is non existent and overseas producers can do it on the cheap even for small production runs if you supply an STL file or similar. (Of course they like your design as they now have your idea and may be able to hack your design and sell it.) Heck, a printed circuit board you design can be made for only a few bucks a piece by PCB Way, and you can get it back in a week or two. Technology is great, but the manufacturing is all overseas today. Even the small metal items we used to hand fabricate are now easily done on inexpensive desktop CNC machines allowing amateurs to do fabrication and machining "it in house". Doing the CAD/Design/Printing/CNC work can be extremely time consuming posing the question, should I do this or farm it out. Of course, the problem is finding the shop that will accept your work and do it anymore is getting hard to find. So, I spend the 4 days necessary to design, CAD, print/cut, test, modify, CAD, print/cut, test and after 4 or 5 iterations I make a trinket that will be "damned adequate" for the task.
As for exhaust and other pipe type needs, we still have to go outside unless you are an experienced TIG welder of thin stainless tubing. We can buy the elbows and lengths we need online and even the ball joints for sockets, but again, this is a trial/error/fit issue even if you are copying an existing part and will be time, and learning curve issues.
As you well know, I'm not saving time or expense doing my own parts, as the enemy of good is better. My redo pile is becoming a need for a recycling means. The work just keeps snowballing. However, it keeps me out of getting in trouble as idle hands can and will find inappropriate ways to stay occupied. At least this is productive to me.
Stay safe,
Bud Yerly
--
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
