Leaking flywheel... AGAIN!

[rizzz]

Mike,
Check out this post on the legendary Bob Hoover VW blog:
http://bobhooversblog.blogspot.com.au/2 ... -seal.html
It might explain some things.

Sounds like the AeroVee manual would benefit from some of these tidbits of wisdom!

I know my oil return hole is clear. I check that every time with a long pipe cleaner. As for installing the rear seal, pretty much everyone I know has done it with a rubber mallet or a mallet and a block of wood. I've removed 2 seals, and in both cases there was no damage, no nicks, no cuts and no sign of leaks coming from the seal. There was evidence of leaks coming from around the 8 pins that hold the flywheel. I'm letting the RTV set up for at least 36 hours (instructions say 24 hours) before trying the engine again.

By the way, for all us male type individuals, did you know there are "instructions" on the tube of RTV? And did you know that after applying RTV you are supposed to wait a full hour before tightening the parts and torquing them? This guy explains it pretty much like the instructions do:
https://www.youtube.com/watch?v=21CvanhKILA

I found the video made by the makers of RTV and Right Stuff to be pretty interesting, too, though if they say their Right Stuff is the best product to use, I'm not sure why they make all the other products:
https://www.youtube.com/watch?v=h_y9FTicNnM

Yeah...
As usual John Monnett and Bob Hoover don't quite see eye to eye on this one.
Both are considered to experts by many and I'm certainly not one, so I can't say whether one is overly perfectionist or the other is overly relaxed in their recommendations. Each of us mere mortals have to make our choice.
However if your problem persists and you''re just not able to find what's actually causing the problem in the first place, maybe try something different is all I'm saying. You can buy a seal installing tool on amazon for $10 if you would want to try Bob's method next time.
That said, none of this matters if the seal installation is not the problem and the oil leak is around the dowel pins.

[mike.smith]

Since I started the thread, I'll perhaps complete it. With all my practice I am now able to single handedly remove an AeroVee, rebuild the entire back side from the fly wheel out (while still hanging from the hoist), reinstall the engine, and wire tie everything back up in 6 hours flat. I feel like an Indy 500 pit crew!

Again I found the leak was coming from the 8 pins holding the flywheel to the hub. The rear seal was 100% intact, but I replaced it anyway. Couldn't hurt, right? The previous sealant at the 8 pins and hub was nearly non-existent. As I had surmised, by tightening up the gland nut while the RTV was still fully wet, apparently that let it ooze out so that there was very little left to stop the oil. So this time I follwed the (red) RTV instructions to the letter, only putting on the gland nut finger tight, and then waiting for a full hour before tightening down the nut and torquing it. I then let the sealant set up for 36 hours before starting the engine.

I took the plane on a 2 hour flight and no leaks! If that changes I'll be sure to let you know.

[Klimek]

There is caution given about using RTV under the cylinders on the AeroVee and certified engines. Theoretically the ultra thin layer remaining can cause cylinder movement and later failure. Is there the same possibility of flywheel to crank movement and failure? Why is there no o-ring in the flywheel? How much red goo do I use?
I really disliked taking my engine back off. I was very proud of the way all the wiring was routed and secured. Just hope I haven't gotten too old to do it again.
Frank
ONEX090

[mike.smith]

There is caution given about using RTV under the cylinders on the AeroVee and certified engines. Theoretically the ultra thin layer remaining can cause cylinder movement and later failure. Is there the same possibility of flywheel to crank movement and failure?

That's what I have wondered. Plus, since you can't measure for the rear shims with the sealant in place, you have to do it dry. Now you add the RTV and you've added thickness back there that is not taken up by the shims, so all the end play measurements are for naught. Sounds like a really bad deal. I think a good O-ring would be a much better solution than using the RTV.

How much red goo do I use?

Good question, with no good answer.

[Gripdana]

I was told that RTV on cylinders and case halves is a bad idea because any excess on the inside of the case will end up in the case and in the oil to potentially clog the oil passages.

[mike.smith]

Right, but we're talking here about the flywheel and hub, not cylinders and cases. Sonex does not call for RTV at cylinders or cases. They use Permatex.

[wlarson861]

Klimek
You don't need to take the entire engine off the mount. Leave the accessory plate (red anodized) attached to the motor mount and just remove the engine section. This leaves all the wires attached to the plane and gives access to the flywheel. The only wires that need to be removed are the spark plug wires.

[Sonex541]

I have been using hondabond or yamabond instead of rtv for years i used it to re seal my cylinders and it has been great , its what they use on Honda , Yamaha's motorcycles from the factory. , you can buy it online or any motorcycle dealer ,
Adam Simmons
Sonex
541sx

[Bryan Cotton]

Hey flywheel experts,
I'm about to pull the engine off the airplane. I'm in the middle of annual, and one thing I have to do is to re-shim the engine as it has sagged a little bit. While I have it off, I want to address the biggest oil leak in my collection, which seems to be coming from the back of the engine. I'm thinking it is the seal.

I've been reading the threads, looking at the manual, and watching some of Joe Norris's Aerovee videos. It seems like my best bet would be to do this sequence:
1) Unbolt the engine from the accessory plate and remove it, with the accessory plate still on the engine mount.
2) Remove the trigger shaft for the secondary ignition
3) Remove the exhaust so I can lay the engine on the bench
4) Remove the flywheel
5) Replace the seal
6) Replace the flywheel, allowing time for RTV to cure before torquing the gland nut.

Does that sound right?

Thankfully, Northern Illinois weather in January SUCKS!

[pappas]

I was never able to get my Aerovee to stop leaking completely. The back of the engine was always weeping to some degree. But, another possible remedy that might help to keep some oil inside is this.

I had a leak at the prop flange that would not go away. The oil slinger just wasn't sufficient to keep the oil inside the engine. I also had a pretty good leak at the rear seal. I purchased the Anti-Splat oil separator and installed it with the drain kit plumbed to the exhaust per instructions. It creates a small vacuum inside the engine case, reducing the internal crankcase pressure and the front oil leak stopped completely and immediately. The rear engine seep was considerably reduced as well.

I also went through the process of installing several rear seals, using different sealers, waiting 24 -36 hours for it to set up before final tightening, etc, etc, etc. I am a pretty good mechanic but keeping the Aerovee dry was certainly frustrating for me. There must be a better way. I haven't found it.