97 - 01 Toyota Camry Iridium Spark Plug Replacement / PCV Cleaning / Valve Cover Gasket Tightening

To keep your Camry in top notch running condition, consider replacing the standard factory double electrode spark plugs to Iridium plugs. Iridiums generate a bigger spark, last just as long as Platinum plugs and are now the auto industry standard on new vehicles. It's the simplest and cheapest performance enhancement that can be made to improve fuel economy and power. Denso and NGK were the first to provide these plugs and were very expensive when first introduced over 10 years ago. Now Champion, Autolite and Bosch provide their own versions at competitive prices. The standard center electrode diameter is .6 mm with Denso being the only company with a .4 mm plug to produce even a hotter spark but sacrifices longevity. Iridiums work extremely well in forced induction turbo applications where air and fuel is being 'rammed' into combustion chamber requiring high quality plugs for complete and efficient combustion.

Some mechanics will refuse to replace or deviate from the manufacturer's stated spark plug brand and type. Iridium plugs have been throughly tested by the auto industry and as previously mentioned, are now provided as standard equipment on many new car applications. Replacing the obsolete spark plug design to the new state of the art Iridiums will not harm the engine in any way.

When replacing the plugs, either clean or replace the PCV (Positive Crankcase Ventilation) valve to allow unburned carbon blow-by gases to be re-channeled back into your combustion chamber. A closed stuck valve will allow these gases to react with the motor oil and possibly cause the formation of engine oil sludge; a controversial subject that Toyota contended with in the late 90's. In addition, the pressure caused by a closed stuck valve will create internal engine pressures that can create an oil leak passage through either the crankshaft, camshaft and oil pump seal requiring their replacement. The PCV valve on the Camry is located on the valve cover between the number 2 and 3 ignition wires.

When the ignition wires are pulled to gain access to the plugs, there is a valve cover locking nut for each spark plug hole. These nuts have a tendency to loosen allowing oil to leak from the back side of the valve cover. In very bad cases, the oil will leak may form behind the front passenger side wheel. Re-tightening these nuts will eliminate the leakage. If an oil leak continues to this area after tightening up the valve cover nuts, the problem may be attributed to: 1. A Worn Crankshaft, camshaft or oil pump seal. 2. A worn oil pump rubber gasket. The procedures for their replacement can be found within my timing belt replacement article.

I. Spark Plug Removal

a. Spray the Ignition wire clips with Silicone and detach wires for the clips. Without this lubrication runs the risk of breaking off the clip from the Valve Cover.

b. Detach the right most driver's side ignition wire from the Coil Pack; otherwise there is not enough wire length to remove the wire from the spark plug tube.

c. Pinch, twist and pull up on the rubber ignition wire nipple above the rectangular cap to detach the wire from the plug. If this proves difficult, pinch and pull with long nose needle nose pliers using the base of the valve cover for leverage. *WARNING - Regardless of how careful you are at wire removal, you run the risk of wire damage if the wire does not detach easily from the plug. This could be due to the ignition wire rubber boot fusing to the plug's ceramic insulator. Use silicone or di-electric grease on the boots during re-installation.

d. Remove the Plugs using a 3/8 Sock Wrench attached to a 4" extension and 5/8" spark plug socket. If the plugs seem frozen in place, spray penetrating oil in the plug hole and let the oil saturate to the threads. Combine loosing and tightening action to allow the oil to migrate.

II. PCV Valve Removal and Cleaning

a. Using long nose needle nose pliers, position the plier tips under the lip of the PCV base and use the Valve Cover as a leverage base to pull up on the valve.

b. Position the PCV hose clamp away from the PCV outlet and twist off the valve from the hose.

c. Shake the PCV valve. If relatively free of carbon, the internal spring can be heard. Regardless, spray in Carb Cleaner at both openings of the valve, seal openings with thumb and index finger then shake. Keep shaking until the internal spring and plunger move freely. Drain the Carb Cleaner.

d. Reverse above steps for re-installation.

III. Tighten the Valve Cover Locking Nuts.

a. Use a 30mm 1/2" Socket.

b. Alternate the tightening sequence from the inside out. That is plug holes 3, 1, 2, 4. Do not completely tighten each nut. Gradually spread out the tension.

IV. Install the new spark plugs

a. If the threads in the cylinder head seem corroded, use a thread chasing tool to clean them up.

b. Use anti-seize lubricant on the spark plug threads to prevent plug seizure for the next change.

c. Don't use a 1/2" socket wrench to install the new plugs. A 3/8" provides just about the right amount of torque for a tight spark plug fit. If unsure on the proper amount of tension, use a 3/8" torque wrench.

d. Lubricate the tips and the interior caps of the ignition wires with silicone or di-electric grease to ease installation and future removal.

e.  Carefully attach the ignition wire clips.  Too much pressure will snap off the clip from the Valve Cover.