New member
I have an 82 westy with an auxillary heater underneath, i'm thinking of having the van undercoated, it has no rust and i thought it would be good to keep it that way, any concerns regarding the heater or undercoating in general? thanks all, vwmorty

A. Cooper

New member
If your '82 Westy with auxiliary heater (gas, I presume) is anything like my '83 diesel with aux. heater, there is a large, flat sheet-metal shroud covering the bottom of the van in the area around the aux. heater. This should protect the heater from any undercoating application.

But if you want to really get into all the nooks and crannies on the underside, you should remove that shroud and then wrap the aux. heater and attendant components in a heavy plastic or similar to protect it from the overspray. Then remove the plastic and reassemble.

NOTE: Volkswagens of all makes are reputed to be very well undercoated at the factory, so unless yours has been removed or damaged, you may not need it. Read the other posts under "Paint and Body Rust Questions" for more info regarding the prevention of seam rust, the real killer of Vanagon bodies.


New member
thanks for the plastic advice, i noticed that big plate covering the heater, there was also a larger metal 'screen' that was covering a lot of the bottom that i took off, put on by the previous owner i suspect, i noticed that the bottom did look well undercoated and it makes sense for the seams to be vulneralble. What about the insulation (is there any) preventing spray rust inhibitor from getting into the panels? I noticed the usual plastic round covers where it was sprayed prviously, the van hasn't been driven in the winter so that's a bonus.

Capt. Mike

VW's undercoating practices have been spotty. By the Vanagon era, they had switched to a factory applied "lost wax" system. It's not really wax but it looks amber-yellowish. Wyuth and others supplied it and Wyuth sells it in the US in spray cans. It's strong point is that it's 'self-healing', i.e. small scratches and scuffs will flow in from adjacent areas to recoat.

Early in the Type II bubble window era, undercoating was often done POE or at the dealership. This often resembled a 3-stooges production. It was usually the black tar type. I've seen this type of undercoating sprayed on brakes, exhaust sytems and the heat-ducts. Makes for interesting smells and smoke on a new car!

Caution: Some types of aftermarket undercoating could dissolve, cause to harden, or otherwise damage this original system. They may use a distillate base or curing/drying agents not compatible with the OE system!!

VW's use of the plugs has to be taken as gospel. Some plugs are to reseal and prevent intrustion of water and road salts. Other apparent plug holes are left open on purpose for condensation drainage or ventilation. Sorry, no magic rule. Go by the dealer's parts fiche.

Most modern body shops, especially those that work on European vehicles, will have excellent undercoating repair equipment. I am NOT a big fan of the chain shops. They are only as good as their staff -- often the bottom end of the mechanic/body shop crowd -- and their practices are usually for speed, not quality. Some will mechanically punch holes in the body, which in turn creates breaks and ragged edges for rust to begin. I've got kin in Wisconsin's salt that have tried the major chains with crummy results. Some of the workmanship I saw was disgraceful.

I suggest you repair the underside every so often. After a thorough cleaning -- steam or hot high-pressure wash -- touch up the damage and abraided sections. You'll find road spray will eat off undercoating in areas. That's not a condemnation of the undercoating, just a fact of life. Some of the better ones don't fully harden and can absorb some impact without fracturing or chipping.

3M makes a good "rubberized" undercoating. It looks and acts much like the old tar-style. It appears to be compatible with the factory -- in fact mine came with a black coating on the bottom. I use it after every major camping trip where I've been on a lot of gravel roads and have done so on 3 generations of Westies with 3 different undercoatings.

If you question the ability of gravel road spray to damage the bottom, consider that the wiring harnesses that run across the vehicle frame to feed the rear heater on my vehicle actually had the cover sand-blasted off. Fortunately, I caught it before it got to the wire insulation and have put additional covers on it.