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Removing and Repairing Oil Contamination in Corvette Fiberglass

Oil-Canned!

Scotty Lachenauer Jun 1, 2017
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When Chevrolet came out with the all-new Corvette in 1953, its fiberglass body was a bold step in modern automotive technology and manufacturing. It had plenty of advantages for sure, with weight reduction the obvious plus of using this composite body material. It was also economical as it avoided the significant out-of-pocket expenditure of having to create sheetmetal-stamping dies. Throw in that it’s impervious to rust and, well, your argument for plastic-bodied Chevys looks pretty good at this point.

It also had its disadvantages. Though fiberglass didn’t dent, it would crack on impact, as the material just doesn’t absorb the energy of a typical crash very well. That revelation led to safety concerns with the sporty composite car. The fiberglass also deformed with heat, so even a small engine fire could transform nearby body panels into a twisted, melted mess. And it was not as durable as metal as it was susceptible to cracking and breakdown by sunlight and everyday wear and tear.

Even though fiberglass has its pros and cons, there’s another issue that could be a problem down the road, affecting your fiberglass body repairs and maintenance. That problem is oil contamination. Fiberglass will draw oil and other like contaminants in like a rigid sponge. And once they are there, they can be a bear to get rid of. Unfortunately, painting over contaminated fiberglass is not an option as over time that oil will flow and move to the surface, adding bubbles and other surface aberrations to your newly painted panels.

Douglas Ims of Starlight Restorations in Egg Harbor City, New Jersey, has been dealing with this dilemma for the last 20 years. Starlight excels in working with fiberglass bodied Corvettes, and he’s seen firsthand what oil can do to a paintjob. So we are here to watch Doug as he tackles a problem that many of you out there may one day face; how to rid your fiberglass Chevy of permeating, problematic fluids once and for all. Doug will first weep as much fluid as possible, and then take to grinding out the oil-besieged areas of contaminated glass. Once that is accomplished, the area will be restored to OEM condition with new fiberglass and filler.

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1. So here’s the starting point on our 1966 Corvette. At some point during its life the car had a catastrophic engine failure, tossing fluid all over the engine bay and front end, as indicated by the dark areas.

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2. This photo shows the extent of the damage. Doug will thoroughly inspect the issues, take it all in and then devise a game plan to remove the oil and contaminants permanently.

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3. And here’s our first stop. Oil has made its way into the fiberglass surrounding the nose emblem. This is shown by the dark rings circling the emblem mounting holes. Doug’s already got a plan on how to rid this area of its unwanted intruder.

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4. Here are the tools Doug will use to start the job. Left to right: acetone and clean rags, a mini 90-degree die grinder with a 36-grit disc, some 40-grit sandpaper and a dual-action sander with some 36-grit discs.

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5. Doug heats up the area with a lamp to help force the contaminants to the surface. Heat, whether from natural sunlight or a powerful lamp is a great tool for this process. For several weeks the Corvette will bake outside in the sun or inside under the heat lamp to raise the contaminants to the surface.

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6. After a small amount of oil reaches the surface, Doug wipes it away quickly with acetone and a clean rag. This is the best solvent to use as it dries extremely fast and will not soak into the fiberglass as much as other slower drying solvents.

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7. After a few heat-up sessions and acetone wipes you can see that a lot of the contamination has disappeared. But that’s not good enough, as even traces of oil will destroy a good paintjob.

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8. Even after you think all the oil is gone, it is still best to remove as much of the fiberglass from the contaminated site as possible. Doug grinds the ’glass down to paper thin thickness in the center, and tapers it out around the perimeter to give more surface area for the fiberglass to bond to.

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9. Here’s the emblem area, finish sanded and ready for new fiberglass to be added where needed.

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10. We can see oil creeping out along the edge of the headlight opening. This will be treated with a series of heat lamp and acetone wash cycles, and then it will get ground back as needed, just like Doug did with the emblem holes.

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11. After a series of heating/acetone wipe sessions, the surrounding fiberglass was ground to a nice taper, from paper thin along the edges to OEM fiberglass thickness where it meets the untouched ’glass. While it sat overnight, more oil crept out. The only option was to remove more ’glass, grinding it back to the steel reinforcement.

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12. The decontaminated site is ready for the first step in the repair process. First, Doug lays out a tape perimeter to isolate the repair area.

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13. For the first layer, Doug uses a mixture of epoxy resin and fumed silica. The fumed silica is a filler substance, and when mixed with the epoxy resin it will thicken and help create a barrier between the old and the newly laid fiberglass sheet that will be applied later on.

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14. The mixture is applied with an acid brush and built up to the desired thickness to ensure that the epoxy resin gets the best bond possible and fills in the area in need.

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15. Once this mixture cures, Doug will grind it back and down to prepare the site for the next step. Curing is done overnight to ensure it has totally hardened and is solid throughout.

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16. In order for him to prepare for the first layer of fiberglass, Doug will need a few tools, seen here: a large grinder, the mini 90-degree die grinder, an air saw, some 40-grit sandpaper stuck to some paint sticks, 40-grit on a short block and two 1/8-inch gauges to measure for gap clearance.

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17. Doug shows the new lower fascia that he replaced. It was a wise decision to do this complete replacement as this area was hit hard with oil, and probably would never have been fully decontaminated. (See sidebar.)

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18. Here, Doug uses the mini grinder with 36-grit paper to cut down the silica compound. He will level it off in preparation for the addition of new fiberglass mat.

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19. But before he can do that, he uses a sanding block with 40-grit sandpaper to clean up the surface. He will continue to work the area until he’s satisfied he can get to the resin/fiberglass work done in order to get the ’glass thickness back up to snuff.

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20. Doug will need to build this area back up. He starts by shimming a metal plate between the fiberglass edge and the reinforcement metal. He adds a 1/8-inch wood shim to get some separation between the new ’glass and steel and then covers it in tape to aid in removal when the fiberglass has cured.

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21. Here it is all ready for the new ’glass that will form the perimeter of the headlight housing.

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22. Once the repair site is prepped, the first of three layers of fiberglass can be laid down. Doug starts by cutting and dry fitting the pieces on his repair areas. Once all the pieces are cut, they get laid out on a table in order so they can be saturated with epoxy resin.

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23. A grooved aluminum roller is used to laminate the layers of glass together and work air bubbles out from the resin and fiberglass.

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24. Here you can see the first round of fiberglass has been laid on the front end. In all, three layers of ’glass will be added, and will be ground flat once they fully cure.

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25. The first round of ’glass has cured, been ground down and sanded smooth with 36-grit paper on a DA sander. The repair site will now be redied to tape out and lay down the next layer of fiberglass.

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26. The last layer of fiberglass sheet is necessary to blend everything together and ensure that the repair site will be the proper thickness. It’s best to do all repairs with fiberglass and leave body filler for the minor imperfections.

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27. The gaps between the hood, front surround and headlight housing are very close, and can now be fine-tuned with body filler where necessary. The new fiberglass has been blocked down flat to meet the level of the existing ’glass and is now ready for a skim coat of body filler.


Bringing Oil to the Surface

We showed that Starlight Restorations replaced the complete lower nose section of this 1966 due to heavy oil contamination. Doug realized that due to the fact that there was a catastrophic engine failure (which sent oil throughout the engine bay), this particular panel got the brunt of it. This is mainly due to the fact that it’s a lower facing panel with a concave upper surface so the oil just sat on top of much of the surface and had plenty of time to sink into and permeate the fiberglass.

Here we have a piece of the front fascia that was removed. Doug left the panel out in the sun/heat for several hours to show how quickly oil can surface on a saturated piece using heat. At the start he wiped the surface dry with a water-based cleaner and then hit it with some acetone to thoroughly wipe it clean. What we’re showing here is the how much the panel was still weeping oil at several intervals over the course of three days.

The photos show that after the first 48 hours there was a large amount of oil that surfaced. We then wiped it clean again, removing the contamination and started with a fresh panel again. You can see how quickly more oil came back after the first wipe down. Doug was smart to call this panel a total loss because it’s just too saturated to save. Time intervals are marked on the photos; each slash representing one hour and complete days are marked at 24 and 48 hours.

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28. Panel cleaned and ready for sun baking.

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29. After 2 hours of sun/heat. Notice the dark oil specs appearing.

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30. After 4 hours of baking. More oil appears.

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31. Close-up after 24 hours. The piece is nearly saturated.

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32. After 48 hours of sun baking. The edges are fully saturated. We are ready to wipe it clean.

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33. The piece after the acetone and cloth wipe down. Notice how this process lifted the oil from the panel.

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34. Even after the wipe down, only 18 hours later the panel was again saturated with oil. Removal of this piece and replacement was the only option.

Photography by the Author & Douglas Ims

Sources

Starlight Restorations
609-445-5936
Starlight Restorations Facebook Page

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