Quarter Panel rust

[project_x]

Like just about everyone in the northern half of the continent... I have some rust on my rear quarter (a hole in the drivers and heavy surface on the passenger).
When stick my finger in the hole... I can feel a lot of crude and dirt. How does it get in there... and how does one get it out?
On the driver's side with the hole... it is easy...Rust made a convenient hole

I'm going to cut out the rust and replace that side...which gives me a chance to treat all the rust inside...

On the other side, I see the rear plugs that I can pull out and I guess try to run water thru the drains....What do I do to make sure I stop the rust inside the rear quarter.

Thanks,
Rob

 

[project_x]

The entire bottom of the quarter panel cavity seems to be filled with dirt... and when it gets wet... collects moisture and destroys the panel from the inside...

Has anyone found a reliable way to clean these out?

 

[B-train]

Isn't there some body plugs on the back side? Maybe remove a couple snd blow air in and vacuum out the other?

 

[project_x]

Isn't there some body plugs on the back side? Maybe remove a couple snd blow air in and vacuum out the other?

That's exactly what I've been doing... but i still mind there is "mud" in the bottom of the one I can get my finger in....
I'm thinking of plugging the drains, filling it up and letting it soak for a few hours and then spray water and air to get it all out....

 

[B-train]

Or, just leave them open, use some sort of pick or stick to stir it up and let it dry out. Then blow/suck it out. Maybe a right angle air nozzle would be your friend, or a flexible one to bend to the bottom and sweep around.

I wouldn't add more water to the corrosion concoction if it were me unless I knew there was an ultimate low spot to drain from.