Valve Stem Seal
Valve stem seals are small rubber seals on top of the valve guides that stop oil running down the valve stems into the cylinders.
What is Valve Stem Seal?
They let through just enough oil to lubricate the stem. Over time heat hardens the rubber and it stops sealing well. They can often be replaced without removing the cylinder head, using special tools.
How it works
The lip of the seal wipes the stem as the valve moves, leaving a thin oil film.
Why it matters for your car
Hardened seals typically cause a puff of blue smoke after start-up or after long idling, and higher oil use. Worn piston rings can cause similar symptoms, so a compression or leak-down test helps decide.
Other terms
- Boot Lid (Trunk Lid)
- Contact Breaker Points
- Convertible Roof (Soft Top Or Folding Hard Top)
- Coolant Temperature Sensor
- Cooling System Pressure Tester
- Cylinder Liner (Sleeve)
- Defensive Driving
- Dipstick
- Flasher Relay (Turn Signal Relay)
- Head-up Display (HUD)
- Oil Pump
- Paint Oxidation (Faded Paint)
- Ratchet Strap
- Retreaded Tyre
- Roundabout
- Serpentine Belt (Auxiliary Belt)
- Speed Rating
- SUV (Sport Utility Vehicle)
- Valve Seat Recession
- Vehicle Registration Document