Sealing Exhaust

[lpaaruule]

Has anyone has success sealing the exhaust where the 3 pipes fit into the one pipe?

One my exhaust, this 3-1 slip fit is very sloppy. There is probably more than a 1/16" gap where I can see exhaust gas soot.

I've tried the exhaust paste, but that garbage just cracks and crumbles. I've also wrapping the slip fit junction worth exhaust wrap. I'm thinking of trying the Permetex copper high heat RTV, but doubt that will hold up.

This all stems from me wanting to get the carbon monoxide level below 10PPM. My last flight it would hover in the mid to upper 20s, and sometimes come close to setting the alarm at 35PPM. After landing it went above 50PPM. BTW, I've sealed every hole that any speck of light shown through the firewall.

Anyway, if there aren't other ideas, and the copper RTV doesn't work, I think I'm going to have the slip fit welded.

[daleandee]

Anyway, if there are to ideas, and the copper RTV doesn't work, I think I'm going to have the slip fit welded.

Hi Paul,

I'm guessing you're referring to the Jabiru 3300 exhaust system. There was discussion about this on the Jabiru Yahoo Group. I believe you have to be a member to view the messages: https://groups.yahoo.com/neo/groups/JabCamit/conversations/messages

I fly a Corvair and it doesn't have this concern as the head is one piece and the three into one exhaust system is also. I mention that because the baffles on the Jabiru are known to crack and I believe if you welded the exhaust the same thing would happen as the separate heads tend to heat differently and move separately. That movement would cause cracking, if not at the welded joint, somewhere else in the system.

As much of a pain as it might be, using something similar to the Rotax "cup & ball system " might work. We used to keep them lubed but they sealed pretty well against the movement.

Dunno if this helps at all ...

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
168.7 hours / Status - Flying
Member # 109 - Florida Sonex Association
https://www.youtube.com/watch?v=1VP7UYEqQ-g

[lpaaruule]

Thanks Dale. Yes, I'm referring to the Jabiru 3300. I signed up for the Yahoo Jabiru group and will check it out if I'm allowed in.

[daleandee]

Thanks Dale. Yes, I'm referring to the Jabiru 3300. I signed up for the Yahoo Jabiru group and will check it out if I'm allowed in.

Paul,

There is also the Jabiru Owners Group: http://www.jabiruownersgroup.org/index.php

I'm not a member but you can scan messages without being a member. After a quick look I didn't see anything relating to your question. Perhaps you might ...

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
168.7 hours / Status - Flying
Member # 109 - Florida Sonex Association
https://www.youtube.com/watch?v=1VP7UYEqQ-g

[peter anson]

Hi Paul,
Until I read your post a bit more carefully I was going to suggest sealing your firewall a bit more carefully, especially at the corners, but it sounds like you have done that. I have the same 3 to 1 exhaust system and high CO levels have never been a problem, but the only monitoring I have done is with one of those little colour-changing cards. How are you measuring the CO levels?

Peter

[lpaaruule]

Hi Peter,

I'm using this Sensorcon digital CO meter: https://www.amazon.com/gp/product/B004YUEPBW/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

I removed the belt clip, and have it velcroed to my instrument panel. I was actaully going to post a seperate message about the meter because I'm really impressed with it so far.

I still have a chemical color changing card, and it doesn't change at all (indicating everything is fine). The only time the chemical card changed was during a run-up before I ever flew the Sonex. Since then I've spent a lot of time sealing everything I can, and it's much better than before. I'm guessing that the remainder is coming from my cabin heat muff that's right behind the slip fit. I'm planning on double checking the RTV on the heat muff, and even tape over the cabin heat vent just to verify.

This FAA advisory circular really got my attention: https://www.faa.gov/documentLibrary/med ... 20-32B.pdf
It asks, "IS YOUR AIRCRAFT A DEATHTRAP? Concentrations of CO exceeding one part in 20,000 parts of air (0.005 percent) are hazardous." That's 50 PPM. I've seen more than that with the electronic meter, and would have not known it if I was only using the chemical card, as mine didn't change.

[sonex892.]

Hi Paul

David A made a clever bead roller tool to seal the engine pipes where they enter the 3 into 1 collector. it looks to be the best solution for sealing the pipes I've seen. I found this image on the old Yahoo Sonexplans site. https://groups.yahoo.com/neo/groups/son ... 0junction/



I reckon the exhaust will be way too hot for even high temp RTV.

Steve
Sonex 892.

[lpaaruule]

Thanks Steve, the bead roller solution looks like it would work well. I'm going to send David an email, and see if I can borrow it instead of building it myself.

[gammaxy]

I've also only used the CO cards, so can't provide any numbers to compare.

Since it sounds like you've done a good job sealing the firewall, I wonder if the CO might be leaking in through any of the holes on the tail?

[lpaaruule]

Hi Chris,

I suppose the tail is another place to look. I taped over a couple areas of the tail section, but didn't notice any difference. I'll look into it more if taping over the cabin heat doesn't work.

I suppose it could also be entering all the rivet holes on the bottom of the plane...there's hundreds of tiny holes there, even with the rivet stems in place, as I saw while sealing the firewall.