Valve guides are integral to the proper operation of engines. The guides help regulate the air intake and compression by keeping valves in place as the engine works. Guides also cool down the valves, with the guide absorbing about one-quarter of the heat generated. By constantly accommodating the valve stems as they thrust in and out with great friction, the guides are susceptible to eventually wearing out. This can cause of bevy of problems. There are several ways to determine if your vehicle's valve guides are worn out.
Observe your car when you accelerate and brake. If you see a billow of smoke from the exhaust pipe -- especially any blue smoke, which is caused by burning oil -- it is a sign that the valve guides are worn.
Time how long it takes the car to consume a new quart of engine oil. Worn valve guides cause a much faster oil consumption rate.
Open the bonnet, and locate the valve guides, using the owner's manual for guidance.
Move the valve into the guide, and try to jiggle it from side to side. Any movement in the guide indicates that the valve guide has corroded.
Measure the inside circumference of the valve guide, and the outer circumference of the valve with a gauge set. Compare the data with the optimum measurements listed in the owner's manual to test whether the valve guides are worn.
Locate the spark plugs based on information in the owner's manual, and check for signs of grey or brown debris. If the ash appears on only one side of the spark plug, it could be a sign of worn valve guides.
Buy a gauge set specifically made to measure valve guides at an auto parts store for the most accurate data.
Do not attempt to handle or measure valve guides unless the engine is completely cool.