I just put a patch on the lower part of the cowl on my car. (where the cowl panel meets the rocker panel) I took the heater out and all hvac stuff. so inside the cowl where the heater core would have been there is just an empty cavity. after patching it i sprayed some foam insulation thinking it would prevent moisture from getting in there and cause an issue later. but after sitting on it for a few hours i started to think was this a mistake? i dont want to have an issue with fire or anything. Its far away from the exhaust and the engine. But does any one see this as being a problem.???

 

You'll definitely get condensation in that area due to heating and cooling...which will cause rust. If you've already welded in a patch panel, I'd just clean out the foam.

 

You're worried about the foam starting on fire? Not unless you take a blow torch to it, but I recommend not doing that.

 

my 79 was in a fire, when the body shop burned down... i am a fire prevention fanatic... but im not concerned about moisture getting in there, because the panel is filled with the insulation and it will expand and fill the area preventing moisture.

 

That foam insulation is not moisture proof. It will actually soak up moisture and hold it there to let it work on your sheetmetal longer. I'd dig that stuff out of there. I've seen it in buildings where water got to it, and it's not pretty!