Ford Mustang 1989-1993 Repair Guide

Valve Lash


No periodic valve lash adjustments are necessary or possible on these engines. Both the 2.3L and 5.0L engines utilize hydraulic valvetrains to automatically maintain proper valve lash. If an engine is determined to have a valve tap, the following inspection procedures can help determine if the hydraulic adjuster is to blame.


2.3L Engine

See Figures 1 and 2

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Fig. Fig. 1: A valve spring compressor tool should be used to collapse the lash adjuster-2.3L

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Fig. Fig. 2: With the adjuster collapsed, use a feeler gauge to check for proper valve clearance

  1. Turn the ignition OFF and disconnect the negative battery cable.
  3. Remove the valve cover.
  5. Position the camshaft so that the base circle of the lobe is facing the cam follower of the valve to be checked.
  7. Using valve spring compressor tool T88T-6565-BH or equivalent, slowly apply pressure to the cam follower until the lash adjuster is completely collapsed.
  9. With the follower collapsed, insert a feeler gauge between the base circle of the camshaft and the follower. The clearance should be 0.040-0.050 in. (1.0-1.3 mm).
  11. If the clearance is excessive, remove the cam follower and inspect for damage.
  13. If the cam follower appears to be intact and not excessively worn, measure the assembled height of the valve spring to make sure the valve is not sticking.
  15. If the assembled height of the valve spring is correct, check the camshaft for wear. If the camshaft dimensions are correct, replace the lash adjuster.
  17. Install the valve cover and any other removed components.

5.0L Engine

See Figures 3 and 4

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Fig. Fig. 3: Use a tappet bleed down wrench and a feeler gauge to check valve clearance

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Fig. Fig. 4: To check all of the valves, the crankshaft must be turned to 3 different positions

The valve lash is not adjustable. If the collapsed lifter clearance is incorrect, different length replacement pushrods are available to compensate.

  1. Remove the valve cover(s) for access to the valves whose lash is being checked.
  3. Either have an assistant help by cranking the engine or install a remote starter switch. Crank the engine with the ignition switch OFF until No.1 piston is at TDC on the compression stroke.

Follow the tool manufacturer's instructions when installing the remote starter switch. In most cases, the BROWN lead (terminal I) and the RED/BLUE lead (terminal S) at the starter relay should be disconnected. Then, install the remove starter switch between the battery and terminal S of the relay.

  1. With the crankshaft in the positions designated in the steps below, piston lifter bleed-down wrench T71P-6513-B, or equivalent, on the rocker arm. Slowly apply pressure to bleed down the lifter until the plunger is completely bottomed. Hold the lifter in this position and check the available clearance between the rocker arm and the valve stem tip with a feeler gauge.
  3. The clearance should be 0.123-0.146 in (3.1-3.7mm). If the clearance is less than specified, install a shorter pushrod to compensate. If the clearance is greater than specified, install a longer pushrod.

An easy way to tell if a cylinder is at TDC of the compression stroke is to watch that cylinder's valves as the engine is cranked or rotated. If the valves remain closed (the rockers don't move) as the piston approaches the top of it's travel, that piston is on its compression stroke (the closed valves were allowing compression to build). If instead, a valve opens as the piston travels upward (releasing compression in that cylinder) then that piston is on its exhaust stroke.

  1. The following valves can be checked with the engine in position No. 1, with the No. 1 piston at TDC on the compression stroke:

    No. 1 intake and No. 1 exhaust
    No. 4 intake and No. 3 exhaust
    No. 8 intake and No. 7 exhaust


  1. Rotate the engine 360° (1 full revolution) from the 1st position (No. 1 is now on its exhaust stroke) and check the following valves:

    No. 3 intake and No. 2 exhaust
    No. 7 intake and No. 6 exhaust


  1. Rotate the engine 90° ( 1 / 4 revolution) from the 2nd position and check the following valves:

    No. 2 intake and No. 4 exhaust
    No. 5 intake and No. 5 exhaust
    No. 6 intake and No. 8 exhaust