I've known that my '86 944 has floorpan rust for quite some time now, and I'm finally getting around to correcting the situation. But I'd like to understand what the cause of the problem is so that after I've made my repairs, it doesn't come back years down the road (no pun intended
).
When I first purchased the car, the driver's side rocker panel was
entirely rotted out at the back; there was about a 6 by 4 inch area of metal completely missing. I've since had that rebuilt (at a fair price, too), but that driver's side is easily where the majority of my rust issues are.
Now, I'm finding that upfront, too, where the floorpan (I think) makes up the fourth side of that square extrusion rail along the outside of the car bottom, there is a large rust hole that I've had to cut out. Inside this frame rail is rusting as well, mostly on the thinner bottom (floor pan) side of the square extrusion. For reference, that hole stretches about from the far left of the pan (just back from the firewall), to just past the brake pedal.
So what could be causing all this rust? Could it be that somehow water is sneaking behind the firewall and pooling in that area? I do know that my battery tray is also Swiss cheese, but of course that would effect the passenger's side of the car first, which isn't half as bad as the driver's side. There's also evidence of a past accident, on that side of the car, but upfront where I don't think it'd make a difference.
It LOOKS like water has been dripping down the pedal board there... but from where?