Heater box repair, any engineers in the crowd?

[mark99]

I am in the process of restoring the inside of the heater box

There are a couple write ups of doing this (thanks!)

The write ups I have found suggest using polyurethane self-adhesive foam

The polyurethane self-adhesive foam I have found is heat rated to ‘only’ 190 degrees F
Without adhesive it is rated at a higher temp, I think it was 220

What do you think? Have you examined the polyurethane after some time?

Apparently the original foam was open cell
I would think open cell would be better for reducing air flow noise
Some people recommend closed cell so it doesn’t absorbed water
I realize there is moister in the air, but no liquid should get in there

Thanks!

 

[HB Chris]

Closed cell will last and not turn to dust, you will never reach 190 degrees.

 

[jmackro]

Some people recommend closed cell so it doesn’t absorbed water
I realize there is moister in the air, but no liquid should get in there

Right! No liquid should get in there. But some will (condensate from the air conditioning, rainwater from the air intake, ...). So go with closed cell - given the way the windows fit on our coupes, you'll never heat he acoustic difference between open and closed.

 

[mark99]

Regarding the temperature, the water in the core is probably 220 and there is foam wrapped around that
but if the adhesive failed there that piece should stay in place
Good point on the noise level, and I probably wouldn't drive it much when it is cold out

So you think closed cell would be more durable? Makes sense

It seems like any foam turns to dust with exposure to air and light
I have an old Triumph, most of the seat is as resilient as it should be, where there was a tear, dust