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Exhaust pipe vs firewall

D

deltamike197

Member
Lately I've been having a strange issue with the right side pipe. I have Vetterman straight pipes on an RV-6A with 180 Lycoming FP. When I preflight I notice the top of the pipe is touching up against the bottom skin. Since these pipes have the ball joint forward of the tail pipe I just gently pull it downward to center it in the open space of the bottom cowl and go fly. But when I return the pipe is sitting against the bottom skin again. It obviously has been touching during engine operation because there is a little bit of the skin worn away in the shape of the radius of the pipe. Anyone experience this? How did you fix it? I have flown the airplane for 4 years now but this hadn't happened until recently and nothing has changed so I'm scratching my head. Thanks

Dean
 
Yup, my -6 has done it since Day 1. I put a wood dowel inside the 3/8" rubber hose which is the same length as the gap between the steel strut tubes. This works well and in 500+ hours I've only replaced the dowel once. Funny how only the RH side is affected.
Heinrich
 
Exhaust vs firewall

Henrich:

I'm not quite sure I'm following...are you talking about inserting the dowel in the black rubber tube in the exhaust hangar that extends down to the exhaust pipe clamp from the engine sump? And the gap measurement is between which steel strut tubes? Please clarify. Thanks

Dean

----------Original message-----------------------------------
Yup, my -6 has done it since Day 1. I put a wood dowel inside the 3/8" rubber hose which is the same length as the gap between the steel strut tubes. This works well and in 500+ hours I've only replaced the dowel once. Funny how only the RH side is affected.
 
It sounds to me like some oil has worked its way into the smashed tube assembly and needs to be taken apart and cleaned with some solvent. If the tube is lightly scuffed and the hose is clean, the hose will vulcanize to the smashed tube after 1 or 2 heat-cool cycles and stay put. Clint
 
Pipe movement

I have a Vetterman 4 pipe on my -4, and instead of the typical rubber mounts, I fabricated a tube for each side that has Hiem ball ends similar to the flight control hinges.They attach to a flange on the collecter/tip bracket, and another flange attached to the engine case/sump. This way it allows for movement created by vibration and heat/cool, but stays fairly rigid to the engine. Some "factory" aircraft have similar set-ups. It is amazing what happens during start-up/shut-down with "shake" that may be causing yours to move so much. I have about 200 hrs on my set-up, and no cracks, loosnes or airframe contact.
 
I had exactly the same happened on the right exhaust pipe and I would do the similar adjustment by pushing down on the pipe. After a flight the pipe will be right back against the bottom of the fuselage. I fixed this issue by readjusting the steel tubing and rubber hoses provided in the Vetterman exhaust kit. The clamps on the rubber hoses need to be very tigth without damaging them. I have now flown for a couple of hundred hours and have not had to re-adjust.
 
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