I have owned my Corolla since 1994. Overall it has been a great car, but like any vehicle it does need maintenance sometimes. The Spark Plug Tube Seals don’t fail often on these vehicles. Mine went bad for the first time around 150,000 miles. I discovered the failure one night when I was driving on the freeway. My car started to stall and almost died as I exited the freeway. I managed to make it home and discovered that three out of the four spark plugs were submerged in motor oil. My first thought was that I had a major engine failure. I then noticed that the plug seals were deteriorated. The seals are mounted inside the valve cover above the spark plug tubes. They prevent oil from leaking past the cover into the plug tubes. If they start to leak, the spark plugs and wires will quickly become soaked and cause a misfire and eventually a no fire condition.
Tools Required
No specialized tools are required for this job.
- · Basic metric ratchet and socket set
- · Common Screwdriver
- · Approximately 1 inch diameter piece of pipe
How to Replace
Ensure that your engine is off and cool. Raise the hood and disconnect the battery. Although your spark plug wires should be cut to length to prevent a mix-up, it is a good idea to label them to avoid incorrect installation. As you are looking at the engine from the front of the vehicle, the cylinders are numbered 1-4 from left to right. This is how you should mark your plug wires. Carefully remove each spark plug wire from the spark plug. Inspect the spark plug wire, spark plug, and spark plug tube for oil contamination. If there are any signs of oil, thoroughly clean the affected components. Remove the top forward timing chain cover bolt. This will allow you to slide the cover over slightly to remove the valve cover. Remove the three valve cover nuts located on top of the valve cover. Try moving the valve cover back and forth to break the seal. If the seal does not want to break, use your screwdriver to carefully pry the cover to break the seal. Do not gouge the cover mount! This could cause oil leaks. Disconnect the PCV vacuum hose and slide the timing chain cover to the side and remove the valve cover. The inside of the cover will be wet with oil so you will want to protect whatever surface you decide to sit it on. Carefully use your screwdriver to pry and push the old seals out. Take note of how the seals were installed because the two sides are different. Do not gouge the seal housing or this will cause leaks! Once the seals are out make sure the housing is clean of all material and oil.
How to Install
Using your pipe, carefully push the new seals into place. Ensure that the seals are not installed backwards and are bottomed out in the top of the housing. This is also a good time to inspect your valve cover gasket. If it is old, may be a good time to replace it while the cover is off. That completes the install of the seals. Installation of the cover is reverse of removal. After installation, start the vehicle and let it run for a few minutes to check for proper operation and leaks. If this is good, take the vehicle out on the freeway or a road where you can drive at least 55 mph or more. This puts a heavier load on the seals to ensure they are seated properly. Once you return home, open the hood and check for oil leaks from the engine and inside the spark plug tubes.
