Polishing Your Valve Cover

What You'll Need

• A new valve cover gasket for reinstallation
• Degreaser, and paint stripper if your cover is painted or coated
• A metal file for casting flash
• Sandpaper in 80, 100, 150, 180, 240, 320, 400 and 600 grit (wet/dry paper for 240 and up)
• A sanding block, a spray bottle or bucket of water for wet sanding
• Aluminum polish such as Wenol, and soft rags or a small buffing wheel on a drill or bench grinder
• Masking tape, safety glasses, gloves and a dust mask

Step by Step

1. Remove the valve cover from the engine. Take off the breather hoses and oil filler cap, and clean the cover thoroughly with degreaser, inside and out. If it's painted or coated, strip it now.
2. File off the casting flash, the thin ridges left where the mold halves met.
3. Start with 80 grit. Most covers need at least 80 grit to remove the deep pits and imperfections in the surface. Keep sanding until all the surface irregularities are gone, and work every area evenly. This is the most important and most time-consuming step. Any pit you leave now will still be there, shiny, at the end.
4. Work up through the grits: 100, 150, 180, 240, 320, 400 and 600. Each grit's job is to remove the scratches from the one before it with finer scratches.
   • Alternate your sanding direction with each grit. When the crosshatch pattern from the last grit disappears, move to the next one.
   • You can skip a grit, but you'll spend far more time sanding out the previous scratches.
   • Use the 240 grit and finer papers wet for the best results.
5. Polish. After 600 grit, finish the cover with aluminum polish such as Wenol, by hand or with a small buffing wheel. Wipe off the black residue with a clean rag as you go.
6. Reinstall the cover with a new gasket, tightening the nuts evenly and only snug. Overtightening distorts the cover and causes leaks.

The Lettering Panel

On covers with a raised "NISSAN" or "NISSAN TURBO" center panel, the classic look is a painted background with polished letters, like the cover in the photo above.

1. Sand and polish the raised letters and panel border along with the rest of the cover.
2. Mask off everything except the recessed panel background.
3. Paint the background with high-temperature engine paint.
4. Once it's dry, lightly sand the tops of the letters with 600 grit wet to remove any overspray, then polish them again.

Keeping the Shine

• Bare polished aluminum dulls over time. A quick pass with aluminum polish every so often brings it right back.
• A clear coat will slow the dulling, but on a hot engine it can yellow or peel and is hard to touch up. Most people just re-polish.
• Avoid harsh wheel cleaners and acid-based products, which can stain the aluminum.