Question about heat shielding front lower cowl

[KazooRV-9A]

Removed the lower cowl on my RV-9A at 12 hours total flight time. Noted this appearance.
Comments on what this discoloration is? Don't see any indication of melting or deformation, on the outside of this area.
Should I install heat shield material?

 

[David Paule]

If it were me, I'd paint the inside of the cowl some gloss white, and then add the heat shield material Van's sells liberally. The white paint makes oil drips easier to clean up.

Dave

 

[Richard Connell]

Yes that’s considerable heat damage. It will likely have delaminated the core from the fiberglass. It certainly will over time.
Agree that painting it will help-it’ll also help stop fluid staining and seeping. any yes definitely also use stick on reflective ceramic backed foil as well where the exhaust is in close proximity to the cowl.

 

[Desert Rat]

The inside of those cowls appear to be pretty porous. To keep oil and crud from soaking into mine I sealed it with a brushed on coat of epoxy with white tint mixed in and then installed stick on heat shield. The edges of the heat shield are sealed down as well.

 

[PaulvS]

This cowl is also painted white inside using epoxy to seal the surface and the silver foil is to help reflect the heat from the exhaust pipes.

The black streak is an oil leak from the front seal, which cleaned off easily (leak has been fixed) . The edges of the foil have been sealed with high temp silicone sealant.

 

[Scott Hersha]

What I’ve done, and you could possibly consider:

. I sanded the inside of the cowl with 80 grit paper.
. Blow off dust with compressed air or vacuum it well with a strong shop vac.
. Wipe down with a clean rag and a solvent, like acetone.
. Paint entire inner surface with bilge paint from your local boat store. (This bilge paint is made to be used on fiberglass, and it is resistant to common boat bilge contaminants like fuel, oil, hydraulic fluids). I used a brush on the first coat to make sure it was forced down into the glass weave/pores. Used a foam roller for the second coat.
. Cover susceptible areas with the stick on aluminum shield sold by Vans. I also put 1/8” fiberfrax under the aluminum shield material in areas where the hot exhaust pipes are close to the cowl.

This has held up very well for 3 1/2 years now, including the bilge paint.

 

[wirejock]

What I’ve done, and you could possibly consider:

. I sanded the inside of the cowl with 80 grit paper.
. Blow off dust with compressed air or vacuum it well with a strong shop vac.
. Wipe down with a clean rag and a solvent, like acetone.
. Paint entire inner surface with bilge paint from your local boat store. (This bilge paint is made to be used on fiberglass, and it is resistant to common boat bilge contaminants like fuel, oil, hydraulic fluids). I used a brush on the first coat to make sure it was forced down into the glass weave/pores. Used a foam roller for the second coat.
. Cover susceptible areas with the stick on aluminum shield sold by Vans. I also put 1/8” fiberfrax under the aluminum shield material in areas where the hot exhaust pipes are close to the cowl.

This has held up very well for 3 1/2 years now, including the bilge paint.

Same as Scott ^ except I first applied neat epoxy. Followed with Kirker White EnduroPrime. Then fiberfrax and foil. Sealed edges with UltraBlack RTV.
AntiSplat exhaust heat shields on the pipes.

 

[KazooRV-9A]

Where would I find info on how to apply Fiberfrax? What have builders used to apply it to the cowl?

 

[wirejock]

Where would I find info on how to apply Fiberfrax? What have builders used to apply it to the cowl?

It has no adhesive. Basically like felt. Most use rtv to stick it in place till the foil is applied. You could also use double sided tape. The Vans foil is what keeps it in place. That stuff is really sticky. Roll the foil down then seal all the edges with Uktra Black RTV.

 

[dmattmul]

This works very well. Adhesive holds great.

https://www.amazon.com/dp/B0055BXW3Q?ref_=ppx_hzod_title_dt_b_fed_asin_title_0_0&th=1