Bite the bullet and buy a new set of valve cover gaskets. Most cork valve cover gaskets usually cost less than $20 and are fairly easy to install on many engines. You may have to disconnect and remove some plumbing or other accessories to get to the valve covers, but on many engines the job is usually within the capabilities of a do-it-yourselfer. If the valve covers are buried or access is difficult, then let a professional replace the gaskets for you.
Tightening the valve cover bolts or screws will rarely stop an oil leak because the gasket is usually cracked, crushed or has lost its natural elasticity. Cork gaskets only last about four to six years before they age harden, become brittle and start to leak. Molded silicone rubber gaskets, on the other hand, (which are used on many late model domestic and import engines) often last the life of the engine. But molded rubber gaskets are a lot more expensive than die cut cork gaskets. That's why cork gaskets have long been used by the vehicle manufacturers.
Some engines do not have gaskets, but instead use a rubbery-glue called "RTV silicone sealer (the "RTV" stands for Room Temperature Vulcanizing). If this is the case, you can remove the valve cover, scrape off all the old RTV, and either apply a fresh bead of RTV silicone sealer to the valve cover flange or head mating surface or install a conventional gasket.
CAUTION: Do not let any pieces of rubber or debris fall into the engine. Also, if you decide to use RTV sealer and your engine has an oxygen sensor (which almost all 1981 and later engines do), make sure the RTV sealer is the "low volatile" variety that is approved for use with oxygen sensors. Some types of RTV give off silicone vapor that can be sucked through the crankcase and contaminate the oxygen sensor.
Changing Air Filter
It's hard to give a specific time or mileage figure because the life of the filter depends on how much crud it ingests. A filter that lasts 20,000 or even 30,000 miles on a vehicle that's driven mostly on expressways may last only a month or two in a rural setting where the vehicle is driven frequently on gravel roads. Changing it annually or every 15,000 miles for preventative maintenance may be a good recommendation for the city driver, but not its country cousin.
Regardless of the mileage or time, a filter should be replaced before it reaches the point where it creates a significant restriction to airflow. But when exactly that point is reached is subject to opinion.
A slightly dirty filter actually cleans more efficiently than a brand new filter. That's because the debris trapped by the filter element helps screen out smaller particles that try to get through. But eventually every filter reaches the point where it causes enough of a pressure drop to restrict airflow. Fuel economy, performance and emissions begin to deteriorate and get progressively worse until the dirty filter is replaced.
Many heavy-duty trucks have a "restriction" meter on the air filter housing that signals when the filter is dirty enough to need replacing. But lacking such a device, the best you can do is guess.
Removing the filter and holding it up to a light will show you how dirty it is. If it's really caked with dirt, it obviously needs to be replaced. Trying to shake or blow the dirt out is a waste of time because too much of it will be embedded in the filter fibers.
NOTE: Many filters that appear to be dirty are in fact still good and do not really need to be replaced. So it's up to you. If you think it's dirty, replace it. If you don't think it's dirty enough to need replacing, then don't.
Regardless of the mileage or time, a filter should be replaced before it reaches the point where it creates a significant restriction to airflow. But when exactly that point is reached is subject to opinion.
A slightly dirty filter actually cleans more efficiently than a brand new filter. That's because the debris trapped by the filter element helps screen out smaller particles that try to get through. But eventually every filter reaches the point where it causes enough of a pressure drop to restrict airflow. Fuel economy, performance and emissions begin to deteriorate and get progressively worse until the dirty filter is replaced.
Many heavy-duty trucks have a "restriction" meter on the air filter housing that signals when the filter is dirty enough to need replacing. But lacking such a device, the best you can do is guess.
Removing the filter and holding it up to a light will show you how dirty it is. If it's really caked with dirt, it obviously needs to be replaced. Trying to shake or blow the dirt out is a waste of time because too much of it will be embedded in the filter fibers.
NOTE: Many filters that appear to be dirty are in fact still good and do not really need to be replaced. So it's up to you. If you think it's dirty, replace it. If you don't think it's dirty enough to need replacing, then don't.
