How to seal heater hose lines hole in firewall

[Desert4x4]

So I changed my heater core and evaporator, but the foam piece that goes around the heater and ac lines on the firewall disintegrated. I now have it installed without it. Can I just use some spray foam to deal the hole up? I'm a little worried about spray foams temperature limits though.

 

[ehall]

Cut some closed-cell foam to fit and fill in the gaps with high-temp sealant

 

[xcm]

Shouldve made a replacement gasket out of mouse pad material while it was still out. You can buy larger sheets (like 18x24") at proper computer stores (Fry's electronics)

 

[md21722]

The dealer sells a foam kit with everything that's needed. It's recommended to buy it when replacing the evaporator and heater core.