The valve cover sits at the top of the engine cylinder head; usually, it’s sealed with a rubber or synthetic gasket that fits into a groove in the metal or plastic cover. The gasket is most often replaced when it begins to leak oil or as a part of other engine work.
The valve cover doesn’t hold a reserve of oil like the oil pan, so oil leaks there tend to seep rather than drip. But being on top of the engine does allow them to cause more problems if the gasket is faulty. Oil can leak from the valve cover onto the exhaust manifold, causing smoke and even fires, and it can coat and damage rubber parts.
Costs of Valve Cover Replacement
On average, it costs about $180 to replace a valve cover gasket, though it can be quite a bit more on many engines.
Here are some estimates of the valve cover gasket replacement cost on some specific common vehicles, using $150 an hour as the labor rate:
- For a 2004 GMC Sierra 1500 with a 5.3-liter engine, the labor time to replace either of the two valve cover gaskets is 0.7 of an hour. An individual factory replacement gasket lists for $21, and a Felpro set costs about $20. The total cost to complete the job for either side would be about $115 either way.
- For a 2015 Nissan Altima with a 2.5-liter engine, the labor time to replace the valve cover gasket is 1.3 hours. A factory gasket costs about $34, and an Apex gasket costs about $20. The total cost to complete the job would be about $229 using factory parts, or about $215 using aftermarket parts.
- For a 2005 Subaru Legacy with a 2.5-liter engine, the labor time to replace the valve cover gaskets is at 0.9 for the right side and 1.1 hours for the left side. An individual factory valve cover gasket lists for $20, and a Beck/Arnley gasket set costs about $45. The total cost for the the job would be about $155 for the right side and $185 for the left side using OE parts, or about $180 for the right side and another $165 to do the left side as well, using aftermarket parts.
- For a 2010 Chevrolet Traverse with a 3.6-liter engine, the labor times to replace either valve cover gasket are 3.5 hours each (access is very tight and obstructed for both). A factory gasket set costs about $70, and a Mahle gasket set costs about $80. The total cost to complete the job would be about $595 per side using OE parts, or about $605 using aftermarket parts.
One thing to keep in mind is that you can usually get individual valve cover gaskets from a dealer source. However, most aftermarket suppliers will bundle all the necessary parts together. In addition to the gasket itself, there are often rubber grommets that seal the bolts holding the valve cover down and seals that go around the spark plug tubes. As a rule, all of these should be replaced during a valve cover gasket replacement. Generally, the quality of name-brand aftermarket gaskets and seals is excellent, and getting all the parts in one package is a good advantage.
PRO TIP – On a V-6 or V-8 engine, there will be two valve covers, and if only one is replaced, the unused parts from a set are usually given to the customer if asked for, in case they are needed later.
Valve Cover Gasket Replacement
Generally, a visual inspection is good enough; if a valve cover leaks, there will be black oily residue on the top areas of the engine, which will collect dust and grime. If there are no leaks, the engine should remain clean and dry, though perhaps just dusty.
On some engines, the crankcase is fully sealed and under vacuum at idle and during normal operation. The valve cover gasket is also supposed to hold the vacuum. But a problem that causes an oil leak in the valve cover gasket under some conditions can also cause a vacuum leak under other conditions, which can cause the engine to run poorly; misfires and lean-running conditions are possible. If the engine has spark plug tubes coming up through the valve cover, these can leak oil into the spark plug tubes, which also causes misfires.
If a valve cover leaks onto the exhaust, it can cause a burning smell, and if ignored for too long, it can lead to an engine fire. If oil leaks saturate rubber parts (such as radiator hoses or engine mounts) for long enough, they can weaken and fail.
Valve Cover Gasket Replacement
Replacement of the valve cover gasket involves moving out of the way whatever wiring harnesses or obstructions there are, sometimes removing coils or spark plug wires, then unbolting and removing the cover. The surface of the cylinder head that the gasket seals against needs to be smooth and clean, Often, there are formed corners that the new gasket doesn’t sit against firmly. These are sealed with a small bead of gasket material, which also requires cleaning off the old gasket material first.
What Else Might Go Wrong?
Many newer engines use plastic valve covers. In some cases, these are prone to warping and are generally replaced rather than just having new gaskets installed. Usually gaskets are available, but even without warping issues, they can be more difficult to get sealed back up than conventional metal valve covers. Recommendations to replace the valve cover and gasket together are common on engines that use plastic valve covers.
In any case, when a leaking valve cover gasket is being replaced, it is a good idea to do a quick check of the engine’s crankcase pressure. The cylinder head has open passages to the engine crankcase, where any compression gases that escape past the piston rings wind up. This is also called “blow-by”. If there is an excess of this, the crankcase becomes pressurized and prone to forcing oil out.
The PCV system, or positive crankcase ventilation, is designed to remove combustion gases from the crankcase and recycle them into the engine air intake. This system minimizes crankcase pressure and reduces any tendency to develop leaks.
If crankcase pressure is suspected, it is a good idea to check the PCV valve. The PCV valve was at one time a regularly replaced service item as it was prone to clogging and failing. Newer engines run cleaner, and problems are rarer, but they can still fail. On older engine designs, the PCV valve is just a cheap screw-in or plug-in component that is usually just replaced if it is suspected of causing problems.
In some modern engines, the PCV valve is permanently built into the valve cover and is only replaceable by replacing the valve cover. If a valve cover is being removed in order to replace the gasket or other seals, it’s a good idea to verify that the PCV valve is functioning normally. If it’s not, the most economical time to replace the valve cover/PCV valve is when it is already removed.
- Can I drive with a leaking valve cover gasket?
Generally yes. Most leaks are slow and minor enough to be almost inconsequential, and can be repaired when convenient rather than as an emergency. A leak onto the exhaust manifold would be the exception, as that can cause an engine fire.
- Will a valve cover gasket leak cause running problems?
In most cases, no, it shouldn’t cause any problems. Two exceptions would be: if it allows oil to leak into the spark plug tubes (where it can cause misfires), or if it is a sealed engine and the gasket failure is the cause of a vacuum leak.
- How often should the valve cover gasket be replaced?
There is no scheduled maintenance interval for the gasket, and generally, there’s no reason to replace it if it’s not leaking. Some will last the life of the engine, though if the valve cover is removed for other work, the gasket is usually replaced.
- Do I need to change the oil if I replace the valve cover gasket?
Not necessarily, but it’s generally a good practice to change the oil any time the engine is opened up for service, as foreign material is easily introduced during the job.