I have started seeing rust and some bubbling paint on the rocker panel (?) at the base of the van sides, below where the side doors are.

I was of the impression this lower compartment was closed. I now see, from under the van, weeps on the inside edge.
Is there water draining down into these bottom panels?
On my '88 Volvo, water from the intake grille drained into the rocker panels.
Is that the case with the Express? Is there water feeding into the bottom sides from somewhere else?

I do see numerous plastic plugs under the van, behind and above the outside face of the rocker panel.
On my '88 Volvo, there were access plugs, inside the cabin, to allow cleaning out the rocker panels.
The plugs under the van are hard plastic and do not, at first glace, appear they can be removable.
The hard plastic plugs are above the weeps so even removed I do not see how dirt at the base of the rocker panel would be cleaned out.
But the plugs are there, so does someone know for what purpose?

Are there suggestions for cleaning and remediation of rust in this area?

 

Unfortunately, by the time you see the rust and paint blisters on the outside paint, the metal behind it is mostly gone.

GM, in its quest for cheapness, brought the inner and outer panel together as a seam facing the roadway. It does a wonderful job of wicking up water into the inside of those panels which are unpainted and rust immediately.

There are companies like LMC and others who sell replacement rocker panels for our vans.

 

Rocker panels have been rusting out for how many decades?
How is that a better design solution has not evolved?

Some seemingly simple things:
- like the ability to flush out the hollow space
- interior treatment of panel surfaces
- a maintenance treatment to inhibit rust.

 

RoadTrip,

Do you know anything about the round plugs located on the sides of the rocker panel?

 

Those plugs can allow access into the rocker area. Most body plugs can be carefully pried out and reinstalled. A heat gun for removal and soaking a minute in very hot water before reinstallation will help make them reusable. Most authentic hardware stores sell plastic plugs like these so you could get replacements, and then there’s always online sources.

Products such as POR-15 have a spray version with a 4-way nozzle wand to coat the inside of the rocker area.

 

Thank you for the advice, but I still did not understand everything. If I have a situation where these panels have not rusted through yet, what will be the best option?

 

I’m sorry to say, it’s gone. No amount of rust killing/blocking/preventive chemicals will save it now. You need to contact a company that sells replacement rocker panels and have a body shop or other professional replace them.

 

Thank you for your reply. Unfortunately, my google gives me not much useful information about it but I found some related videos on youtube and now have an idea how it is going to work. Just trying to figure out how much it will cost.