|Going Under Cover |
Before you start, purchase a replacement gasket set and
some sealant. See step eleven for details.
Get the service manual and open it to the requisite
page. Every engine is different, and you’ll want a reference guide to show you
things. Do you know the proper torque value and the torque pattern for the
cover bolts? If not, get the manual. Many municipal libraries have complete
collections for check-out.
Always disconnect the battery before starting any engine
work. Remove anything that may be in the way of the cam/rocker cover coming
out. Those items may include the PCV hoses, throttle cables, spark plug wires,
and the air cleaner hoses and housing. Label every hose and wire with colored
tape or a paint pen, as you may forget what goes where when you’re all done.
Undo the fasteners holding on the cam cover and put them
in a dish for safekeeping. This may require some unexpected tools, such as
deep sockets or thin-wall sockets. Modern engine compartments are cramped,
forcing engineers to get creative with how they arrange the fasteners. If the
cam cover won’t budge, do another check around to see if you missed a bolt.
If you’re very lucky, the cam cover will pop right off.
If it has been there a long time or was put on with an adhesive sealant, the
job of removing it may get tough. Try tapping it gently with a rubber mallet
all around the base of the cover. Never use a metal hammer, as you will dent a
stamped-steel cover or crack a plastic or aluminum cover. Tap close to a
corner, where the seal will be the weakest. If you lift the cover in the
corner, get a flat object such as a broad screwdriver or paint scraper (or an
actual hook-shaped seal remover, if you have one) underneath and work it
around the gasket as you lift up. Work slowly and cautiously. A screwdriver
can easily gouge and permanently damage a soft aluminum cylinder head casting.
Apply only gentle pressure until it is off. This could take a while.
It’s off! Now behold the clockwork innards of your
engine, which may be seeing daylight for the first time since it was built. If
your engine is overhead cam, you’ll see one (called a single overhead-cam) or
two (a double overhead-cam) long, straight shafts with what look like eggs
stuck on them. These are the camshafts and cam lobes which open the valves. At
one end of the camshafts will be a sprocket for the timing chain or timing
belt. Now is the time to inspect the cams and valve gear for wear. You won’t
be able to see normal wear, which happens in the thousandths of inch, but you
can look for obvious trouble signs. Those include burnt cam lobes, spalling
(flaking) of the lobe’s hardened surface or pitting of the lobe. All of these
are signs of advanced cam wear, which will have to be addressed by a
If your engine has solid or non-self-adjusting valve
lifters, this would be a good time to check clearances and adjust the valves.
All engines are built with a certain amount of slop, or space, between the
tappets – which press the valves open – and the actual valve stems. As an
engine ages, the valves recede into their seats, closing that gap. Most new
cars have self-adjusting valve lifters. If yours doesn’t, check your shop
manual for the correct procedure on how to check and adjust. Depending on the
car, this may be one job for the pro mechanic. Note: do not run the engine
with the cam cover off. Oil will fly everywhere.
If you’re working outside or in a dusty place, take a
drycleaner bag or garbage bag and put it over the exposed cylinder head to
keep grit from getting in the engine.
Clean the cam/rocker cover. Use an old deep-dish baking
pan or a disposable aluminum foil turkey pan from the grocery store and pour
in a few cups of mineral spirits or lacquer thinner (both available by the
gallon at home stores) to dissolve the grease. Wearing chemical-resistant
gloves to protect your skin and safety glasses to protect your eyes, clean the
cover inside and out with an old toothbrush or paint brush. If the cover is
aluminum, don’t use a steel brush, as it will gouge the aluminum. A brass
brush or a stiff-bristle brush and a plastic scraper is good for removing the
old baked-on gasket. Properly dispose of solvents. The best way is your city’s
household hazardous waste drop-off site, which is usually free.
After the cover is degreased, it’s time to decide if
you want to paint it, replace it with an aftermarket cover, or just stick it
back on. If you paint the outside of the cover, you’ll have to further clean
the cover to remove all trace of oils and residues from the degreasing agent.
Most auto parts stores sell a pre-paint degreaser that does not leave a
residue. Use a clean cloth, and don’t touch the cover with your hands as even
the natural oils on your fingertips can cause the paint to “fish-eye.” Most
auto parts stores sell a variety of colors and finishes in spray cans.
Options: paint the cover the same color as the body. Paint it red. Paint it
black with the manufacturer’s logo polished up or hand-painted in red. Krylon
markets a line of spray-on wrinkle finishes that will give your cam covers the
same look as a Ferrari’s. For best results with wrinkle paint, follow the
direction on the can to the letter. Plastic covers will be harder to paint.
You must use a paint that is compatible with plastic, such as hobby enamel,
though it may not wear as well over time.
Time to reinstall the cover. You will have purchased a
gasket for it already. The gasket may be made out of cork, paper, or
pre-formed silicon. The latter is by far the best, though it costs the most.
If the auto parts store gives you the option, consider spending the extra
money on a pre-formed silicon gasket. They are molded to fit the shape of your
cover, often have steel bolt eyes in them that prevent over-torque of the
bolts, and do not require a gasket dressing.
Reinstall the fasteners and reattach the loose hoses