Water Stuck Behind Rocker Panels?

atfcharger · September 4, 2011

Hello,

Have not posted in a long time as I was issue-free with my truck until recently. It's an '03 Sierra 1500 and I noticed a few weeks ago I had water bubbles in paint on the rockers. I figured it was from rock chips and rain and such had gotten in there. I didn't actually think it was rusting from behind the panel...

Wanting to prevent further stone and debris damage I picked up a Herculiner kit from Fleet Farm on sale for $40 and figured all I'd have to do is clean and prep the water blisters, prime the bare metal from the blister spots (after I'd sanded them down clean the rust off), and then go through the instructions of applyin the liner.

I washed the truck on Thursday, August 25 and parked in the garage. Last week I peeled of the blistered paint and sanded down the affected areas to clean metal and got rid of the rust. The surfaces were prepped and primed with two coats and I left it sit the rest of the week.

Now tonight I go out to start masking and prepping for the Herculiner and I find that more water somehow blistered through the primer! See attached pic. Apparently it's rusting from behind the panel? I could barely tell there was even a pin hole in the metal but there must be. How do I get the water out from behind the panel? Is this why it's still weeping?

I'm just a weekend garage guy. After searching a bit online it seems rocker panel rust is just part of owning the truck, but at this point I'd like to finish my Herculiner job even if it doesn't do anything than hide what's going on behind it.

It looks like there's three layers of stamped metal in the rocker area (other, inner, and a middle piece)? For as high up on the rocker as the picture shows, is there water trapped?

Thanks for any info on this! I just want to get it back on the road!

Rons05z71 · September 21, 2011

Hello,

Have not posted in a long time as I was issue-free with my truck until recently. It's an '03 Sierra 1500 and I noticed a few weeks ago I had water bubbles in paint on the rockers. I figured it was from rock chips and rain and such had gotten in there. I didn't actually think it was rusting from behind the panel...

Wanting to prevent further stone and debris damage I picked up a Herculiner kit from Fleet Farm on sale for $40 and figured all I'd have to do is clean and prep the water blisters, prime the bare metal from the blister spots (after I'd sanded them down clean the rust off), and then go through the instructions of applyin the liner.

I washed the truck on Thursday, August 25 and parked in the garage. Last week I peeled of the blistered paint and sanded down the affected areas to clean metal and got rid of the rust. The surfaces were prepped and primed with two coats and I left it sit the rest of the week.

Now tonight I go out to start masking and prepping for the Herculiner and I find that more water somehow blistered through the primer! See attached pic. Apparently it's rusting from behind the panel? I could barely tell there was even a pin hole in the metal but there must be. How do I get the water out from behind the panel? Is this why it's still weeping?

I'm just a weekend garage guy. After searching a bit online it seems rocker panel rust is just part of owning the truck, but at this point I'd like to finish my Herculiner job even if it doesn't do anything than hide what's going on behind it.

It looks like there's three layers of stamped metal in the rocker area (other, inner, and a middle piece)? For as high up on the rocker as the picture shows, is there water trapped?

Thanks for any info on this! I just want to get it back on the road!

I think I have the same problem in that general area. There are drain channels and mine were clogged. If you crawl under the truck and feel back around the rocker panels there are some channels

Austin83 · September 21, 2011

Do you live up north or near the ocean?

Drifthopper · September 22, 2011

atf.... know exactly what you are typing about, and must live in a northern state where road salt is used. if you look underneith and maybe someone else will reply, but its rusting from behind, i'd suggest getting in there from undernith and spray some heavy oil to try to slow it down.

Good Luck.