Paint Cracking, Fading, and/or Peeling

dave8412  Jun 16 2006 - 10:09am   

Q: Why does the paint on my car seem to fade/crack/peel so easily?

A: Up through the 1987 model year, F-cars were built at two different assembly plants. One was Norwood, Ohio and the other was in Van Nuys, California. The plants both built the two F-cars identically, except with respect to the paint process.

Since before the 3rd generation F-cars were started in late 1981, the Van Nuys plant was forced to use a water-based enamel paint because of the very restrictive CA laws enforced by the CARB (California Air Resources Board). This water-based paint was very different from the solvent-based paint used at Norwood. Another difference was the way the paints were applied. Because it was mostly non-polluting, the water-based paint at Van Nuys could be sprayed on by a conventional spray-gun technique. There were no volatile solvents (only water), and whatever paint did not stick to the cars (overspray) was caught by air filters.

Starting with the 3rd generation models, Norwood began using a much more sophisticated paint application mechanism called a Turbo Bell. The Turbo Bells were high speed (30K RPM) turbines that literally atomized (fogged) the paint so very little solvent was required (much less than with conventional spraying techniques). The Turbo Bells dispense a cone shaped fog of electrically charged high-solids enamel. This fog would be up to 55% solid paint, with volatile organic solvents as the carrier. The charged paint particles would be attracted to the vehicle body, which was also electrically charged (with opposite polarity from the paint) so that the paint particles would attract and stick. Very little overspray would result from this process, since the high-solids paint fog would be attracted directly on to the vehicle by the electric charge. The carrier solvent would evaporate, and was drawn into burning stacks where it would be incinerated.

The Turbo Bell painting technique is now used by virtually all manufacturers and combined with solvent-borne enamel like that used at Norwood, results in the highest quality paint jobs. In 1987, Norwood turned turned out some of the finest quality paint jobs in the world. By comparison, the water-based paint would be much more dull, thin, and prone to problems.

The much stricter CARB emissions laws did not allow the use of solvent borne paint at Van Nuys. That meant that the paint jobs coming out of Van Nuys could never be as good as those from Norwood. The water based paint was not as hard, or shiny as the solvent based paint used at Norwood. Then came some real problems. Due to the ever-tightening CARB standards, Van Nuys was forced to give up the spray guns and adopt the Turbo Bell paint application system for the '86 model year. You would think that this sounds good, but the problem was that the Turbo Bell system was designed for solvent based paint and not the water-based paint mandated by CARB at Van Nuys. There was a period where they had not really sorted out how to re-formulate the water-based paint and primers to work with the Turbo Bells, and this resulted in many problems especially during the '86 model year. It took several years for some of the problems to be solved.

You can tell where your vehicle was built by looking at the 11th digit of the VIN. If it's an "N", then the car was built at Norwood, if it's an "L", then the car was built at Van Nuys. Another interesting difference (although there's no concrete evidence) is that cars which were built at Norwood had the top of the cowl painted over in flat black, while vehicles built at Van Nuys left this area body colored.

The Norwood plant was closed after the 1987 model year finished out, as GM had decided that F-car production could only sustain a single plant, and the Van Nuys plant was the more modern of the two. Also, Van Nuys was a larger plant, and had only a two level conveyor system rather than the complicated 5-level system used at Norwood. The more constricted Norwood plant only turned out about 41 vehicles per hour, while 54 per hour could be sustained at Van Nuys. Each F-car took about 20 hours to assemble completely from start to finish. Unfortunately the plant that remained open (Van Nuys) had the poorer quality paint process due mainly to the mandated use of water- based enamel. All remaining 3rd generation F-cars from 1988 through 1992 were built at Van Nuys. All 4th generation F-car production moved to Ste. Therese in Canada.

It is also believed that paint problems in 1988-1992 models are a result of GM reformulating the primer base which was put on the cars. The primer was made to better stick to the sheet metal/fiberglass and better resist rust and corrosion. Unfortunately, it also resisted the paint from sticking to it - better known as "delamination". Thus, after a number of years, the paint starts to unadhere from the primer base even to the point where it will peel off in sheets. GM will cover repainting of vehicles with such delamination problems, but only up until they're 5 years old. This is why GM released technical service bulletin #231054 which allows dealerships to handle such problems on a "case by case basis to give goodwill adjustments to customers".

 
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