7 Symptoms of Bad Valve Guide Seals
Are your valve guide seals worn out and leaking oil where they shouldn’t? You might be dealing with a time bomb under your hood. If left unchecked, defective valve guide seals can cause serious damage to your engine. So it’s important to detect this problem early. We’ll explain the most common symptoms of bad valve guide seals and how much they can cost to replace.
What are valve guide seals? Their purpose is to keep the lubricating oil in the valve cover from entering the combustion chamber, lubricate the valves, and ensure proper valve positioning.
The valves play a vital role in opening and closing the intake and exhaust chambers of the engine at the right time. This time is controlled by the cams on the camshaft. The cams on the camshaft have an elongated shape.
Valve guide seal replacement cost
The movement of the valves is timed with the movement of the pistons using a timing belt or chain. The valve stem is the long, thin part of the valve. A small flat disc at the end (called the head) seals the combustion chamber when the valve is closed. Each combustion chamber cylinder has at least one intake valve and one exhaust valve.
Oil circulates directly over the valves to lubricate the camshaft, but this excess oil needs to be prevented from entering the combustion chamber. This is the job of the valve guide seal. The guide seal also guides the valve into the valve seat in the cylinder head, keeping the valve stem in the proper position.
Common Symptoms of a Bad Valve Guide Seal If your valve guide seal is bad, you will notice several issues, most of which are exhaust related. It is important to understand the symptoms so that you can take appropriate action if you notice them. Here are some of the most common signs of a failing valve guide seal:
1) Blue Exhaust Smoke
Perhaps the most common sign of a bad valve guide seal is blue-gray smoke coming from the exhaust, especially on initial start-up. The smoke will be strongest when you start your car’s engine, as it has had time for the oil to build up.
However, smoke can also occur while idling or accelerating.
Do not confuse this with the small white smoke (steam) that comes out of the exhaust pipe during start-up due to normal condensation, especially in cold weather.
2) Excessive oil consumption
Excessive oil consumption is often the first symptom you will notice with a leaking valve guide seal. If oil gets into the cylinders, it will simply burn off while the engine is running. You may need to add oil more frequently or experience oil loss between oil changes.
3) Engine Braking
Engine braking uses engine vacuum instead of braking to slow the car. To do this, you release the accelerator and downshift to a lower gear to increase engine rpm. The increased engine speed and lower gear ratio increase engine vacuum, creating resistance to forward movement and slowing the vehicle.
When engine braking on a hill, do not press the accelerator pedal. If the vehicle is nose down, oil will collect at the front of the cylinder head near the valve seal. It will then burn and produce a lot of smoke from the exhaust.
4) Oil in the Spark Plug Well
The valve guide leads from the cylinder head to the combustion chamber of the engine. When these seals wear, oil can leak past the seal and into the valve guide. Gravity also draws the oil from the valve guide area into the spark plug wells above each cylinder.
5) Poor Performance
Misfiring and sluggish acceleration can be an issue when valve seals wear out as oil burns and leaves ash in the spark plugs and combustion chamber. Check for fouled spark plugs. Compression testing of a vehicle with a faulty valve guide seal may reveal abnormally high compression. If you notice low compression along with these other symptoms, you may instead suspect faulty piston rings or a leaking head gasket.
6) Tinkling noises from the engine
When starting the car, ticking and rattling noises can occur if parts in the engine are misaligned or have excessive play between them. Valve guide seals lubricate and properly align the valve parts, so defective valve seals can cause the valves to become misaligned or not receive proper lubrication.
7) Rattling noises from the valves
When excessive clearance occurs between the valve stem and guide due to worn seals or oil loss, rattling and knocking noises can occur from the valves and lifters. This is most noticeable at idle. This noise indicates worn parts causing valve chatter or play.