United States
CanadaWhat Do Valve Stem Seals Do?
Designed to control how much oil lubricates the valve stem, valve stem seals play an important role in engine lubrication. These seals allow a controlled amount of oil to lubricate the valve stem as it moves in the valve guide. Without these seals controlling the flow of oil, it can cause many issues like excess oil in the combustion chamber, fouled spark plugs, increased oil consumption and catalytic converter degradation.
What Are the Different Valve Stem Seal Designs?
There are three designs of valve stem seals – positive, deflector and O-ring.
Positive – The most common style used in today’s vehicles, positive seals are attached to the valve guide boss and function as squeegees. They wipe and meter oil on the stem as they pass through the seals.
Deflector – Also known as umbrella seals, this type of seal is secured to the valve stem and moves with the valve to shield the valve guide from excess oil.
O-ring – Found mostly on small block Chevrolet engines, this style of valve stem seal fits in a second groove on the valve stem, just below the keeper groove. Some applications use both O-ring and umbrella type seals together.
Replacing Valve Stem Seals
New valve stem seals can be installed on or off the vehicle. While the process is similar, there are some differences depending on which variation you choose. From removing the old seals to installing new Fel-Pro valve stem seals, follow these steps for a successful repair.
On-Vehicle Procedure
Step 1
Remove valve cover, valve train and spark plugs.
Step 2
Bring the piston to top dead center of the cylinder that you’re starting with.
Step 3
Introduce compressed air into the cylinder; this keeps the valves closed against the cylinder head.
Step 4
Using a valve spring compressor, compress the spring. Use a magnet to grab the valve keepers. Remove the spring with the compressor.
Step 5
At this point, you should see the valve stem seal. There are special pliers available for removing positive style valve stem seals. Remove it and clean the valve and valve guide area with degreaser.
Step 6
Check the amount of play the valve stem has in the guide. Check against the manufacturer spec. If it is out of spec, remove the cylinder head(s) and send it out for valve guide work. Replacing valve stem seals with worn valve guides is only a temporary fix for oil consumption.
Step 7
Once clean, you’re ready to install the new seal. Using the included installation tool, put it over the top of the valve. Be sure to use the installation tool; it keeps you from damaging the seal during installation. Slide the valve seal down on the guide/valve. Seat a positive style seal with an appropriately sized socket and lightly tap the seal onto the guide. Remove the installation tool for the next valve. Apply clean oil to valve stem seal after installation.
Umbrella seals are slid past the installation tool and then the spring and keepers installed.
O-ring style seals are installed AFTER the compressed spring is on the head but before the keepers are installed. The O-ring style seals control the oil that puddles up on top of the retainer.
Step 8
Remove the installation tool. Apply a light coat of grease where the keepers are installed. Put the compressed spring onto the cylinder head.
Step 9
Install the keepers. The grease helps hold them in place on top of the valve.
Step 10
Release the compressed spring slowly, making sure the keepers stay in place.
Step 11
Once the compressor is removed, take a soft-face mallet and give the top of the valve a light rap to seat everything.
Step 12
Repeat the process for the other valves on that cylinder.
Step 13
Take air off the cylinder. Rotate the engine over to the next cylinder and repeat the process.
Step 14
Once all seals are done install the valve train, adjust valve clearance (if needed) and install the valve cover with a new Fel-Pro valve cover gasket.
Off-Vehicle Procedure
Step 1
Since the cylinder head is off the vehicle, most jobs will use a C-clamp style spring compressor to remove the valve springs. Keep all springs and keepers in order to ensure they go back to their original location. If cylinder head machine work is to be performed, i.e., valve job, valve guide replacement, resurfacing, etc., the valve stem seals will be installed after this.
Step 2
Lube the valve stem with oil before installing it in the guide. Install the valve into the valve guide and install the seal installation tool over the top of the valve. Install the positive style seal and seat it onto the guide or slide the umbrella seal onto the valve stem. Remove the installation tool.
Step 3
Using a C-clamp style valve spring compressor, compress the spring. If installing an O-ring style seal, install it now. Apply a small amount of grease to the keeper area of the valve. Install the valve keepers and slowly release the tension on the spring. Once the compressor is removed, use a soft-face mallet and give the valve a light rap to seat everything.
Step 4
Repeat this procedure until all are installed.
Step 5
Make sure the engine block deck surface is flat, clean and dry before installing the new Fel-Pro head gasket and the cylinder head. Follow the manufacturer’s instructions for reassembling the engine.
Learn more about Fel-Pro quality gaskets that are specifically designed for the repair environment, find your car part, or find where to buy your auto part today.
The content in this article is for informational purposes only. You should consult with a certified technician or mechanic if you have questions relating to any of the topics covered herein. Tenneco will not be liable for any loss or damage caused by your reliance on any content.