Replacing the valve stem seals on your 1998 Honda Accord with the cylinder head removed is an effective way to fix oil burning and blue smoke from the exhaust caused by worn seals. This technical guide will walk you through the entire process step-by-step.
What are Valve Stem Seals and Why Do They Need to be Replaced?
Valve stem seals are small rubber or silicone rings that fit tightly around the valve stem, sealing the gap between the valve guide and stem. Their purpose is to allow a small amount of oil to lubricate the valve stem and guide while preventing excess oil from being drawn into the combustion chamber.
Over time, the valve stem seals can become brittle, cracked, or shrink due to age and exposure to heat, allowing oil to leak past. This results in the engine burning oil, producing blue smoke from the exhaust, and reducing engine performance. Replacing the worn valve stem seals will restore proper oil control.
What are the Symptoms of Worn Out Valve Stem Seals?
- Blue smoke from the exhaust, especially after sitting overnight
- Rough idle or misfire due to oil fouling the spark plugs
- Excessive oil consumption and need to top off frequently
- Burning oil smell from the engine
- Reduced engine performance and fuel economy
If you notice one or more of these symptoms, there is a good chance your Honda’s valve stem seals need to be replaced. Performing a leak-down test can help confirm a valve seal issue.
Tools and Materials Needed for the Job
Having the right tools and parts on hand is key to successfully completing this repair. Here’s what you’ll need:
List of Specialized Tools Required
- Valve spring compressor
- Valve spring removal/installation tool
- Magnetic pick-up tool
- Pliers or valve stem seal removal tool
List of Replacement Parts Needed
- New valve stem seals (intake and exhaust)
- Valve cover gasket
- Cylinder head gasket set
- Intake and exhaust manifold gaskets
- Coolant (to refill system after repair)
Preparation and Disassembly
How to Remove the Cylinder Head
- Disconnect the battery negative cable.
- Drain the cooling system and remove radiator hoses from the head.
- Remove the air intake assembly and throttle body.
- Unbolt and remove the valve cover.
- Remove the timing belt, cam gears, and camshafts.
- Disconnect the exhaust manifold from the head.
- Remove the intake manifold and support brackets.
- Unplug all sensors and disconnect wiring harness from the head.
- Remove the cylinder head bolts in the proper sequence.
- Carefully lift the head off the engine block.
How to Identify and Remove the Valve Stem Seals
With the cylinder head on a workbench, you can now access the valve stem seals:
- Label and organize the valves so you can reinstall them in their original locations.
- The intake valve stem seals usually have a metal spring around them.
- Exhaust valve stem seals are typically all-rubber or have a different color spring.
- Make note of which direction the seals are installed on the guides.
Removing the Old Valve Stem Seals
How to Remove the Old Seals Without Damaging the Valve Stem
- Use a valve spring compressor to compress the spring.
- Remove the valve keepers (locks) with a magnet.
- Carefully release the valve spring compressor.
- Remove the spring retainer and valve spring.
- Pull the old valve stem seal straight up and off the guide.
- Needle nose pliers or a seal removal tool can help grip the seal.
- Be careful not to scratch or damage the valve stem.
- Wipe off any oil and repeat for the remaining valves.
Installing the New Valve Stem Seals
How to Install the New Seals Correctly
- Lubricate the new valve stem seal with clean engine oil.
- Slide the seal onto the valve stem with the open end facing down.
- A seal installation tool makes it easy to push the seal into place.
- The special tool has a deep socket that fits over the seal.
- Gently tap the tool with a hammer until the seal seats on the guide.
- Without a tool, you can use a deep socket of the proper size.
- The socket should contact the top of the seal’s metal flange.
- Rotate the seal on the guide to make sure it is fully seated.
How to Ensure Proper Seating and Alignment
- The valve stem seal should fit tightly on the valve guide.
- Make sure the seal is fully seated and not cocked or damaged.
- Look closely with a flashlight to verify the seal is centered on the guide.
- An improperly installed seal will not control the oil and can fall off.
- Spin the valve and cycle the spring to check that nothing is binding.
Reassembly and Testing
How to Reinstall the Cylinder Head
- Clean the mating surfaces of the block and head.
- Install the new head gasket over the locating dowels.
- Carefully place the head back onto the engine block.
- Tighten the head bolts in 2-3 stages in the proper torque sequence.
- Reinstall the camshafts, timing components, and valve cover.
- Reconnect the intake and exhaust manifolds with new gaskets.
- Reattach all wiring, hoses, and brackets removed from the head.
- Refill the cooling system with the proper mixture of coolant.
How to Test the Valve Stem Seals for Leaks
After completing the reassembly, start the engine and let it warm up to operating temperature. Then, do the following to check for valve seal leaks:
- Visually inspect for oil leaks around the valve cover and head.
- Look for blue smoke from the exhaust, especially at startup.
- The engine should idle smoothly without misfires.
- Check the oil level after running to see if consumption has improved.
- A leak-down test can verify the valve seals are holding compression.
Troubleshooting Common Issues
What to Do if You Encounter Problems During the Replacement Process
- If a valve spring is difficult to compress, the valve may be sticking open.
- Soak the valve stem in penetrating oil and work it back and forth.
- Gently tap the valve back into the closed position if needed.
- The keepers can be tricky to remove and install.
- A magnetic probe with a rubber tip can help grab the keepers.
- Place the keepers in a tray or magnetic parts holder so they don’t get lost.
- If the valve stem seal won’t slide onto the guide, the seal may be the wrong size.
- Double check that you have the correct seals for your engine.
- The valve guide may be worn, preventing the seal from fitting tightly.
How to Diagnose and Fix Common Problems After Replacement
- Blue smoke still coming from the exhaust:
- One or more seals may be damaged or not fully seated on the guides.
- Inspect each seal closely and replace any that are not properly installed.
- Engine misfires or runs roughly after reassembly:
- The camshaft timing may be off by a tooth.
- Verify the timing marks are properly aligned.
- Check that the spark plug tubes are sealed and not leaking oil.
- Coolant leaks after reinstalling the head:
- The head gasket may not be sealing correctly around a water port.
- Retorque the head bolts in sequence to ensure even gasket pressure.
- Check that the surface sealing the gasket is clean and flat.
By following these steps and tips, you can successfully replace the valve stem seals on your 1998 Honda Accord with the head removed. Take your time, organize your parts and tools, and double check your work to avoid leaks and ensure a quality repair.