Thread: fiberglass insulation under hood ??

Tweet

I have a question about the fiberglass insulation under the hood.

Most of the cars I've owned, the 'glass matt is long gone.

But.. the 87 chevette I got is completely stock. It has five bad spots on the paint in the hood. They looked suspicious to me..

well today I got to work on it, and have concluded the rust came thru from the bottom. I suspect the 'glass mat got wet, and held the moisture against the hood. The paint on the underside of the hood was never intended to fight long-term moisture.. and in five spots it ate thru the paint, then thru the steel.

Well, I got the matt off in one piece, and it's in great shape. But I'm not sure I should replace it. I took a grinder to the worst of the rust, and shot some primer over it. Will get some grey paint to cover the primer, but the rust isn't 100% gone, and I am thinking the hood would be better off without the matt.

What do you thinK? replace the matt or no?

I've never been a big fan of the fiberglass stuff - holds moisture like a sponge and then we start the engine heating up the engine compartment with no place for the moisture to go. Engine stops, things cool down and the moisture beads on the underside of the hood. That's a problem..

Some of the new stuff is better for sound deadening and made with a closed-cell construction (the silver stuff). I like it a lot more that the fiberglass stuff that seems to just fall apart anyway!

My two cents says leave it off and if you need some deadening, use the new mats.

Regards,
Glenn

So you say it was for sound, not heat?

Cool. ( ouch, bad pun )

I can just leave it off then. The car is quiet as a churchmouse with a hang over anyway.

Unless you are building the car as a restored original, then I say leave it off. Only cars I see using the mats are those who are trying to be period perfect.