M939A2 hood undercoating

[dilligaf13]

So the hood on my M932A2 tructor has seen better days. It's starting to get some pretty big rust bubbles in more than a few spots. It's weird because the rest of the truck is immaculate, especially since it was a super low mile military refurb when I bought it. I assume there was an issue with the undercoating or prep work with these hoods, for it to rust like this. Was this an issue they addressed with later NOS hoods, was it something they all did, or did I just get lucky??

I'm deciding on if I'm going to just replace the hood with a NOS or play the game of kill the rust, which in South Florida never ends once it starts...

 

[simp5782]

So the hood on my M932A2 tructor has seen better days. It's starting to get some pretty big rust bubbles in more than a few spots. It's weird because the rest of the truck is immaculate, especially since it was a super low mile military refurb when I bought it. I assume there was an issue with the undercoating or prep work with these hoods, for it to rust like this. Was this an issue they addressed with later NOS hoods, was it something they all did, or did I just get lucky??

I'm deciding on if I'm going to just replace the hood with a NOS or play the game of kill the rust, which in South Florida never ends once it starts...

Sand it in the rust area. Spray it with acetone and atv. After 48hrs spray with prune tree spray. Let dry to 48hrs then sand and paint.

 

[dilligaf13]

Yeah, I'm willing to bet money more than a couple of those spots are going to be big old rust holes once I start digging. If it was regular rust I'd just treat, paint, and be done but I'm not looking to repair holes in the hood because I fully expect other spots to just keep popping up over time since there was clearly an issue with these other spots to pop up like this. Trying to figure out if other NOS hoods will have the same piss poor prep or if some earlier ones did and later ones didn't or if it's just a luck of the draw type thing.

 

[98G]

The foamy insulation holds water. I'd blame it on that.

 

[dilligaf13]

Probably a good bet because the fenders have not had the same issues. So what do you think, pull the foam and use dynamat instead?

 

[98G]

Probably a good bet because the fenders have not had the same issues. So what do you think, pull the foam and use dynamat instead?

Your climate isn't mine.

I tend to just pull the foam and not replace with anything....