An engine that’s burning oil spews obvious signs and signals. Clouds of smoke at startup or when getting on and off the throttle visually show where that quart of oil every 500 miles is going. If the dipstick is reading low and there’s no sign of oil smoke, suspect an oil leak.
While the source of oil leaks can be hard to locate, a common and relatively easy to repair source is located where the valve cover meets the cylinder head. If oil is going missing and the area around and under the valve cover is soaked, then it could be time to replace the valve cover gasket.
Symptoms of a Bad or Failing Valve Cover Gasket
There are a few common symptoms that will indicate a potential problem with a bad or failing valve cover gasket. If you recognize any of these warning signs, contact a mechanic as soon as possible so they can replace the valve cover gasket if needed.
Related: What are Engine Valves?
1. Burning oil smell
When a valve cover gasket is pinched, worn out, or cracked, compressed oil from underneath the valve cover will find a way to escape. When this happens while the engine is running, the excess oil will drip on the cylinder head, fuel intake, or in some cases, the exhaust pipes.
These are all hot components that will burn the oil and produce a burning oil smell that is easily recognizable. If you smell burning oil, contact a professional mechanic so they can properly diagnose the cause of the oil leak and fix the problem.
2. Valve cover is dirty and leaking oil
During most oil changes, the technician will inspect the valve cover to see if there is any leaking oil coming from the valve cover gasket. The quickest indication of this problem is when the valve cover/cylinder head is very dirty.
The oil collects dirt and debris under the hood and will appear to be “caked” on the valve cover or cylinder head. If you have the oil changed, or look under your hood and discover that the valve cover is dirty, it’s most likely caused by a bad valve cover gasket.
3. Engine is low on oil
As oil leaks from the valve cover gasket, it leaves the oil pan. When this happens frequently, it can cause the Engine Oil Light to appear on your dashboard. If the engine oil is low, it will reduce its ability to properly lubricate internal engine components.
This can build up excessive heat inside the motor and cause serious engine damage. If you notice the Engine Oil Light is illuminated at any time, don’t delay repair or assume it will turn off on its own. Contact a qualified mechanic to diagnose the problem and repair what is causing the oil leak.
4. Engine is running rough and misfiring
Sometimes when oil leaks from a valve cover gasket it leaks all the way down to the spark plug well and eventually seeps inside the spark plug tubes. This will cause a misfire or reduce engine performance. It can also cause a fire under your hood if it goes unrepaired.
In all of the above scenarios or warning signs, the root issue is typically caused by a valve cover gasket that has broken, is pinched, or has been improperly applied if new. When you notice these symptoms, contact a mechanic to diagnose the problem and replace the bad valve cover gasket correctly.
How to identify a valve cover gasket leak
First, let’s make sure you actually have a leak coming from your valve cover gasket. Nothing is more frustrating than putting a lot of time and energy into solving a problem, only to find out all that work was for nothing and your problem was actually something else.
Luckily valve cover gaskets can usually be pretty easy to diagnose. The valve cover gasket is almost always the highest seal in the engine. Your job is to find the evidence of the leak, or dripping oil and follow the drip higher and higher on the engine until it disappears.
This can be pretty easy if it is on the front or side of the engine, but if the leak is in the back near the firewall, it can be difficult to do without a flashlight and a mirror. The best way to check for a valve cover leak is to move enough things out of the way that you can check the whole perimeter of the valve cover from the top side.
This may involve removing spark plug wires, throttle linkages, or even the intake manifold. Once you have the entire perimeter of the valve cover gasket visible, you need to check for a few things:
Valve cover inspection:
- Loose or missing bolts or screws
- Cracks in the valve cover
- Part of the gasket sticking out from under the valve cover
- Evidence of a leak in the form of oil or black residue around the edge of the valve cover.
Once you’ve proved you have a valve cover gasket or another type of oil leak (if so, you may want to look at an oil leak sealant), you need to decide how to move forward. If you have a missing bolt or screw, it should be replaced immediately.
The easiest way to do that is to remove a second bolt take it to your local hardware store and ask them to match it. When replacing both, make sure to use a torque wrench to torque the bolts to the factory recommended setting.
If you tighten them too much, you can risk breaking the valve cover, and if too loose, they can fall out again or cause a leak. If the valve cover is cracked or broken, get a replacement valve from the dealer, a junkyard, or even try eBay.
How to fix a valve cover gasket leak?
Replace a leaky gasket cover on a 4-cylinder engine easily and in less than an hour for less than $25. We show you how to do it, step-by-step.
- Plastic putty knife
- Rubber mallet
- Socket/ratchet set
- Torque wrench
- Brake cleaner
- Valve cover gasket kit
- Vulcanizing (RTV) sealant
Step 1. Remove the Leaky Valve Gasket Cover
Start the job by removing the decorative plastic cover on the top of the engine (if equipped). Remove the bolts and tap around the valve cover with a soft-faced mallet to break it loose. Never pry with metal tools—they can gouge the aluminum cylinder head and cause permanent leaks.
Next, remove (and label) any hoses, cables, and electrical connectors that attach to the valve cover. Then remove the spark plugs.
If you see any oil pooling in the spark plug tubes, clean it out with a rag wrapped around a screwdriver. Get out as much gunk as you can and then remove and, if necessary, replace the spark plugs with new ones before proceeding.
Once the new plugs are in, remove the valve cover hold-down bolts, noting the length and location of each bolt. Then break the valve cover loose and lift it off the engine.
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Step 2. Replace the Old Gasket
Peel off the old gasket and clean the valve cover with brake cleaner and clean rags. Next, clean the gasket mating surfaces on the engine. Use the plastic putty knife (never metal) to remove any traces of old RTV from the timing belt cover-to-cylinder head.
Catch the old RTV with a rag so it doesn’t fall into the engine. Once the cover and mating surfaces are clean and dry, apply new RTV in the same locations and install the new gasket. Valve cover gaskets are designed to seal “dry,” so don’t apply a sealant to the face of the gasket.
Finish off the job by snugging up the valve cover bolts to the torque specifications in your shop manual. Keep in mind that valve cover bolt specs are usually shown in inch/lbs., not foot/ lbs. To convert inch/lbs. to foot/lbs., simply divide by 12.
Reinstall all the cables, hoses, ignition components, and electrical connectors and fire it up.
Keep your engine clean with these tips.
Step 3. Adding Silicone Sealant
When my dad and I were changing the spark plugs on my Saturn, we noticed oil leaking around them. My dad said it was from a leaky valve cover gasket. A valve cover gasket cost $20 and we had it installed in about 20 minutes it was really easy.
But a few weeks later it was leaking again. We didn’t know we had to smear silicone sealant over the timing cover joint. We redid the whole job, including the goop step this time, and it’s been leak-free ever since.
The best part is, I figure I saved about $100 on valve cover gasket replacement cost!