Cowl exhaust heat damage prevention

[vfrazier]

Another option:

Heat Shield Mat, self adhesive

[Dan B]

I am running the mufflers in parallel for cabin heat on our 9. I have covered the bottom of the cowl with self adhesive heat reflective material from the auto parts store. The left exhaust stack seems to move so I have doubled the clamps on the hangars to try and keep the muffler from getting against the cowl.

http://i1105.photobucket.com/albums/...5/DSCN2575.jpg

[Lars]

Originally Posted by rv9aviator

After the mods my cowl is doing OK but I am having a difficult time keeping the mufflers and tail pipes from moving around after a few hours. Right after I adjust the rubber hose hangers there is about 3/8 of an inch clearance between the back of the muffler and the cowl. After a few hours it will be down to 1/8 of an inch from touching the cowl. I sure wish there was a better system to support the exhaust than hose clamps and fuel hose. I bet it works OK with just pipes but the added weight of the mufflers may be the problem.

After reading a few reports of this, I've been pondering this myself. One suggestion I've read is to try flaring the ends of the stainless steel tubes provided by Vetterman. That would add some mechanical support, instead of just friction between clamped rubber hose and steel tube. I tried that; it makes it a lot harder to assemble the hose onto the tube. I don't like the idea of the relatively sharp edge of the flare biting into the tube ID, since with heat already trying to kill the hose, this could shorten the life even more. I'm going to try an ISO bubble flaring tool next. Bubble flares are used on some automotive brake lines, among other things. It may assembly easier, while still providing a mechanical "stop" for the hose clamp to lodge against.

Is your system mounted per Vetterman's instructions (one set of hangers to the engine, the other to the motor mount)?

[Ron Lee]

Find someone with a tool that creates the outward bulge just a 1/4" or so from each end.

Something like this but rounded instead of triangular

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[Lars]

Originally Posted by Ron Lee

Find someone with a tool that creates the outward bulge just a 1/4" or so from each end.

Something like this but rounded instead of triangular

_______/\__

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That would be an ISO bubble flaring tool

[vlittle]

Originally Posted by vfrazier

Another option:

Heat Shield Mat, self adhesive

I think Tony Bingelis provided a good solution that I used. Use some thin gauge aluminum sheet cut to size in the high heat areas and glue it down with a bead of RTV. Don't squish the bead flat, leaving about a 1/16" air gap between the aluminum and the cowling.

V

[Allen231ah]

Originally Posted by vfrazier

Another option:

Heat Shield Mat, self adhesive

This is what I used after having delamination problems with the stuff I got from Van's . I did lay a coat of plybond down before applying this material . This may have been an overkill , is has good adhesive on the product already . You want to make sure what ever shielding is used is secure , when the one from Van's came loose it shorted between the alt and exhaust stack, could have been ugly .

[chaskuss]

Originally Posted by Ron Lee

Find someone with a tool that creates the outward bulge just a 1/4" or so from each end.

Something like this but rounded instead of triangular

_______/\__

--------\/---

Ron,
The tool you are referring to is called a beading tool. Most of us have seen beeding done on the fuel filters we buy for small engines. Beading is also done for rubber coolant hose connections on our cars. You can find one here. See

http://www.earls.co.uk/earls/accesso...dingtools.html

http://www.aircraftspruce.com/catalo...s/ezbeader.php

Charlie

[Lars]

Originally Posted by chaskuss

Ron,
The tool you are referring to is called a beading tool. Most of us have seen beeding done on the fuel filters we buy for small engines. Beading is also done for rubber coolant hose connections on our cars. You can find one here. See

http://www.earls.co.uk/earls/accesso...dingtools.html

http://www.aircraftspruce.com/catalo...s/ezbeader.php

Charlie

I wish you hadn't posted those links... more tools that I can't live without- there goes the budget

I've used (borrowed) a KD Tools bubble flaring kit, but don't own one. The beader looks like a better tool for this job.

[Lycosaurus]

Originally Posted by rv9aviator

After the mods my cowl is doing OK but I am having a difficult time keeping the mufflers and tail pipes from moving around after a few hours. Right after I adjust the rubber hose hangers there is about 3/8 of an inch clearance between the back of the muffler and the cowl. After a few hours it will be down to 1/8 of an inch from touching the cowl. I sure wish there was a better system to support the exhaust than hose clamps and fuel hose. I bet it works OK with just pipes but the added weight of the mufflers may be the problem.

Jim,

I found that grinding grooves into the stainless metal tube hangers before they are inserted into the rubber hose creates enough grip for the hose not to slip once the clamps are tightened. I made the grooves using a grinding wheel. It works well for me after more than 300 hours.