When the intake and exhaust valves on an engine have achieved a clearance gap that is too large or two small, it can affect the emission of gases from the combustion chamber and hinder engine performance. On several models of Geo Trackers, the engines utilize either an 8-valve system or a 16-valve system; to maintain proper engine functions, valves must maintain a clearance within a range of 0.002 inches. Adjusting the valves on your Geo Tracker can help you solve a serious issue that can result in an engine that stalls or won’t even start.
Shift your Geo Tracker into the neutral gear. Engage the emergency brake.
Pop your Geo Tracker’s hood. Remove all fixtures from the hood of the car blocking your access to the engine’s valve cover. (Reference the service manual specific to your vehicle’s model for information on what equipment should be removed and the proper procedures to do so.) This may include removing the radiator, timing belt or various plug wires.
Remove the valve cover, also referred to as the camshaft cover. Use a socket wrench and an appropriately sized bit to loosen the bolts securing the valve cover to the engine. Pull off the valve cover with your hands. If necessary, use a screwdriver to pry the valve cover away. (Removal of the valve cover will pop the valve cover gasket, requiring replacement later.)
Use feeler gauges to measure the clearances of all intake and exhaust valves on your Geo Tracker’s engine. Each piston should be accompanied by two valves, one intake and one exhaust. On an 8-valve engine, intake valve clearances should measure 0.005 inches to 0.007 inches, and exhaust valve clearances should measure 0.006 inches to 0.008 inches. On 16-valve engines, recommended valve clearance for both intake and exhaust valves are 0.005 to 0.007 inches. Note which valves you want to adjust before moving on.
Bring either the first or fourth piston into the top dead center (TDC) position, depending upon which valves you are adjusting. Rotate the camshaft pulley until either the number 1 or 4, printed on the circumference of the pulley, lines up with the timing cover. For both 8- and 16-valve Geo Tracker engines, adjust all valves for piston one, intake valves for piston two, and exhaust valves for piston three with piston one in the TDC position. With piston four in TDC, adjust all other valves.
Loosen the tappet locknut for the valve you wish to adjust, using a tappet locknut wrench.
With your locknut wrench still attached to the tappet, slide your tappet adjuster tool through the locknut wrench and rotate until it engages the valve adjuster screw inside the tappet. Rotate the adjuster tool clockwise to reduce valve clearance or counterclockwise to increase valve clearance.
Repeat Steps 5 through 7 as necessary for other required adjustments.
Replace the valve cover gasket broken in Step 3 on your valve cover. Place the valve cover in its proper position and secure with the bolts you removed in Step 3. Replace all other fixtures removed prior to valve cover removal, and close the Geo Tracker’s hood.
