The intake and exhaust valves in the Tempo and Topaz are driven by the camshaft. The energy created by the turning of the camshaft drives a series of hydraulic lash adjusters and stamped steel rocker arms. As these rocker arms move back and forth, the individual valve attached to the rocker arm opens and closes. The newly introduced lash adjusters eliminated the need for periodic valve lash adjustments.
It is not uncommon for vehicles equipped with hydraulic lifters to develope a valve tap noise from the top of the engine. Usually this noise is created due to air in the hydraulic assembly. In most cases, the procedure below will eliminate this condition. In the event the noise continues, more involved mechanical repairs may be necessary. Refer to Engine & Engine Overhaul for engine and valve repairs.
To eliminate valve tap noise proceed as follows;
- Park the vehicle on a level surface. Engage the parking brake fully. Place blocks behind the tires.
- Make sure the vehicle is in either PARK or NEUTRAL. Start the car, and allow to run until normal operating temperature is reached.
- Once normal operating temperature is reached, run the car at 2000 rpm for 20 minutes.
- After 20 minutes, shut vehicle off for 2 minutes, then start car and allow to idle for 1-2 minutes.
See Figures 1, 2 and 3
Because the diesel engine does not utilize a hydraulic lifter assembly, the valve lash should be checked at regular intervals. The camshaft is supported by 5 machined bearing bores in the cylinder head. The number 1 and 5 bearing caps are different designs and are easily recognized from each other. The number 2,3 and 4 bearing caps are identical and are numbered accordingly. The bearing caps have arrows cast into the top surface, and must be installed with the arrow to the front of the engine.
The valves are adjusted by changing the valve shims located on top of the cam follower. Each shim has a stamped number located on the bottom of the shim. In the event the number has worn off, use a micrometer to measure the thickness.
To adjust valve lash, proceed as follows:
- Disconnect breather hose from the intake manifold and remove camshaft cover.
- Rotate crankshaft until No. 1 piston is at TDC on the compression stroke.
Using a feeler gauge, check the valve shim-to-cam lobe clearance for No. 1 and No. 2 intake valves, and No. 1 and No. 3 exhaust valves.
Intake Valves: 0.008-0.011 in. (0.20-0.30mm).
- Rotate crankshaft one complete revolution. Measure valve clearance for No. 3 and No. 4 intake valves, and No. 2 and No. 4 exhaust valves.
- If a valve clearance is out of specifications, adjust as follows:
On diesel engines, valve adjustment is accomplished through the installation of shims between the camshaft and valve spring assembly.
- Rotate the crankshaft until the lobe of the valve to be adjusted is down.
- Install cam follower retainer, T84P-6513-B or equivalent.
- Rotate crankshaft until the cam lobe is on the base circle.
- Using O-ring pick tool T71P-19703-C or equivalent, pry the valve adjusting shim out of the cam follower.
- Valve shims are available in thicknesses ranging from 0.13-0.18 in. (3.40mm-4.60mm).
- If the valve was too tight, install a new shim, of the appropriate size.
- If the valve was too loose, install a new shim of the appropriate size.Shim thickness is stamped on valve shim. Install new shim with numbers down, to avoid wearing the numbers off the shim. If numbers have been worn off, use a micrometer to measure shim thickness.
- Rotate crankshaft until cam lobe is down and remove cam follower retainer.
- Recheck valve clearance.
- Repeat Steps 4, 5 and 6 for each valve to be adjusted.
- Make sure the camshaft cover gasket is fully seated in the camshaft cover and install valve cover. Tighten bolts to 5-7 ft. lbs. (7-10 Nm).
- Connect breather hose.
- Start car to check idle and performance of engine.