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Idiot's guide to seam rust repair

From: Chris Turner

ive been listening to people give their ideas about dealing with the seam
rust.. some good, some bad.

if the metal is thin, perforated, or full of holes, then it needs to be cut
out. but if its just SURFACE RUST then cutting out the metal and replacing it
will make it WORSE. yep, worse.

the vanagon is a unibody...the seams are where panels are joined together,
and flanged in, often 3 or 4 panels (that you cannot see) come together at a
seam. you cut all that out, then you have to go inside the van, remove all the
interior panels and weld up all those different panels from the inside, and
below, not to mention the panels you have just disturbed in cavaties you cannot
see - or even get at!!! ..inner rocker panels, where floor is welded to frame
rail, etc, etc... basically this translates into ALOT OF WORK. and alot of
$$. cutting out metal should only be done as a last resort..then the metal
is full of holes or thin.

you have to remember when you cut out metal, and weld in a patch you are
disturbing the original structural integrity of the vehicle..water drain patterns
may be altered/blocked, etc - if the job isnt done 100% right then the outcome
will be worse than what you are trying to fix in the first place. alot of
times, bodyshops will spotweld in new panels or patches - not run a continous
mig weld bead around the patch like should be done - just a spot weld here and
there to hold the piece on. ive even seen some GLUE panels in.. then they
fill around the seams/gaps with bodyfiller, bondo, fiberglass or whatever.
bondo, smooth and a pretty paint job. out of sight out of mind. in a year you
have bondo bubbles in the shape of the patch where the water and rust has come
thru from behind, because the panel wasn't properly welded in. bondo and most
bodyfillers are not water resistant. they will let water thru. bondo is the
worst thing to fix rust holes. bodyshops cut corners. especially on rust
repair jobs. 99% of bodyshops love insurance work, and hate rust repair.

nothing is as good as the factory welds.

for minor seam rust - surface rust - where the metal is still solid - then
no cutting is needed. just proper prep and treatment of the metal.

seam rust comes from behind. like others have said, if you dont take care
of the problem at its orgin, it will return.

* seam rust happens because the body seam sealer that is applied at the
factory, shrinks/cracks, etc and water/dirt/salt/crud goes into the cracks,
exposing the untreated metal, and rust starts. the rust/water etc will take the
path of least resistance - thru the seam.

where vanagons rust:

above bumper "rebar". this is the unibody bumper rebar that your bumper
bolts to. there is a seam between this and the front nose sheetmetal.. this seam
is one of the few vanagons seams that rusts from the OUTSIDE. factory seam
sealer cracks, and water comes in. ive seen vans here totally rotted thru,
needing sheetmetal replacement.

drivers side-
the vertical seam behind the drivers wheelwell, or at the back of the
"dogleg". where your gas cap would be if it were on the drivers side.
this vertical seam rusts from behind..the seam inside the wheelwell. those
of you with '88-'91 vanagons with the full fiberglass bodykit should remove
your sideskirts and inspect these areas. those fancy bodykits do a good job at
concealing the rust.. out of sight, out of mind, out of control..

drivers rocker seam rust-
the drivers rocker seam rust is USUALLY only prevalant on full GL westfalias,
with the 3 accessory fill ports cut int he drivers side.. this can also be
accompanied with rust thru directly below the fill ports. if there is rust
directly below the fill ports, then panel replacement is necessary.
what happens:
when westfalia-weke converts these vanagons into campers at their factory,
they cut the holes into the side of the van for the fill ports/flue vent. then
they install the ports, only using a foam gasket as a seal against the body.
20 years later, this foam seal is dust. water enters around these fill ports,
and flows down the inside wall of the camper. this wall is insulated with
fiberglass insulation, so the water soaks it, and never dries out. there is a
horizontal bodybeam directly below the fill ports, and alot of times water
collects on this beam and the result is the rust-thru you see directly below the
fill ports, right in the middle of the side panel. water also collects at the
seam where the floor meets the sidepanel and rocker seam. water weeps thru the
rocker seam from behind the kitchen area, and there you have your drivers side
rocker seam rust.
if people only re-sealed their accy fill ports, none of this would happen.
simple caulking around the ports will keep water out.

seam rust behind rear wheels-
this seam rust comes from inside the rear wheel wells at the rear
seams..again, its from factory seam sealer shrinking, and water entering seams from

rust around windshield and side window and hatch window seals-
alot of times when you have a glass replacement, the shops use a razor blade
when cutting out the old seal, and paint is scratched, not touched up, and
rust happens under window seal. most of the time its just from dirt/salt/crud
buildup under the seal and then rust starts do develop. you must pull the
windows out to adress this problem

rust at bottom edges of rear hatch-
if you open your hatch and look at each inside bottom corner, there are 2
black plastic plugs. remove them. these do nothing other than hold water inside
your hatch at the bottom, and are the reason the hatches rust out at the
bottom corners. dumb idea from volkswagen to plug the drain holes.

rust at bottom of sliding door-
this is more common on 80-84 sliding doors, but i have seen some 85 up
sliders with bottom rust as well. this is due to a lack of drainholes in the
bottom of the sliding door (only 2) and dirt/salt crud gets built up in the
bottom of the sliding door and rusts out from behind. this is why solid 80-84
sliding doors are extremely hard to find in the northeast.

there are other areas as well, but those are the main ones..

when i repair seam rust, i do this.

go inside the wheelwells, directly opposide of the exterior seam rust, with a
flathead screwdriver. poke around, and you will most likely see the factory
undercoating/seam sealer bubbled up, and scrape off the LOOSE
undercoating/seam sealer. scrape it down until you start to see shiny metal. a small spot
/portable sandblaster is nice if you have it, but not necessary. i use a
drill or dremel with wire wheel attachment, or a wire brush in hard to reach
areas. USE GOGGLES!! wire brust/blast all the loose rust off till,shiny. if the
rust is scaled bad, use a flathead and scrape it down till all the loose
metal is off. then i use some serious grit emery sandpaper.. like 50 grit..
either on a drill or dremel or by hand. use a screwdriver nd pick out all loose
seam sealer, but not the stuff that is still pliable. when the metal is all
cleaned up, then you want to clean it..i use paint thinner/spirits to clean
the metal.

then when the cleaner is dried off, i treat all bare metal with EXTEND..or
RUST MORT..or rustoleum RUST CONVERTER. available at WalMArt..comes in a little
plastic jar. you basically paint it on with a brush.. it goes thru a
chemical transformation and changes the metal to a black look. this has to be done
above 50 degrees or the stuff wont work properly (in colder temps, a hairdryer
will help it cure properly) whent he metal turns black you know its cured

then i take some new seam sealer - available at your local auto parts store
or NAPA, squirt it from a regular caulking gun..into the seams. the seams
only.. dont smear it all over the place, just caulk it into the seams. if you
have a situation where some metal has seperated from the seams, then squirt the
seam sealer into the seams and then tap the metal back down lightly. wipe all
excess seam sealer off that gets on surrounding metal.

once the seam sealer has set up (it will always remain pliable) you can mask
off the area you dont want to get paint or overspray on, with masking tape
and newspaper, and then spray the area with primer. i use rustolem or krylon.
the grey primer.

then (if inside wheelwell surface) spray the whole area with 2 coats of
rubberized undercoating..available at any FLAPS and youre done.

then for (if exterior bodycolor surface) - when the initial primer coat
dries, you can start your filling of the surface abrasions or pits. you can use
fiberglass bodyfiller or spot putty (depending on how deep the pits in the
metal are) to build the surface back up smooth. you want a thin coat. when the
filler/spot putty sets up, then sand smooth..feathering into the surrounding
wipe clean and then follow with another thin coat of spot putty to fill sand
marks or any other pits. then sand with finer grit paper once that sets up.

wipe whole area clean and you are now ready for your top primer coat. mask
off areas you dont want to get overspray on. you dont want to mask off
directly around the repaired area, you want to feather primer out, so you dont get
"tape lines" in the primer.

prime area.. then when dry, sand whole area primed with 1500+ paper ,
feathering all imperfections.

you can use paint thinner to quickly wipe off any unwanted primer overspray,
or laquer thinner if its been on there awhile.

once area is totally dried, sanded, and clean, you are ready for your final
some of the factory paint color are still available from the VW dealer in the
small spray cans. or you can go to and you can find
your color there..they will mix it up for a factory match, and put it in a spray
can for you.

topcoat the whole area that was repaired, using even left to right strokes,
keeping the spray away from the surface so it doesnt run. apply another coat
once dried.
then top with clearcoat if applicable (metallics are clearcoated)

easy. saturday job at the most.

alternatively, if you want to skip the topcoat steps, and just want to do a 5
minute fix to keep the rust from getting worse, the least you can do is
scrape off the loose metal and apply the rust coverter stuff..paint it on..with a
q-tip even.. it will keep the rust from getting any worse until you can fix it

now NOBODY should have an excuse to go around with untreated seam rust on
their vanagons or any car for that matter..

See Comments on this entry (F.W.I.W.)

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