BMW Repair – BMW E46 M3 Valve Adjustment

The M3 e46, MZ3, MZ4 with the S54 engines all use mechanical valve lifters. Although mechanical lifter

vehicles require periodical valve adjustments, they do have much higher R.P.M. capabilities.

On a mechanical lifter engine it is important to maintain clearance between valve stem and valve lifter. This gap is required to compensate for heat expansion.

Without proper valve clearance the valves will not seat fully. A partially open valve will result in compression loss and improper valve cooling. The final result is burnt valves.

The tools used for this job:

Set of feeler gauges, on BMW intake valves you will need a minimum of 7 thousanths & a maximum of 9 thousanths, on the exhaust side a minimum of 11 thousanths & 13 thousanths.
1 inch Micrometer
BMW Shim (puck) Removal Tool
Note Paper – to record the details
Set of shims

To Check the Valve Clearances:

Step 1. Remove the valve cover, spark plugs, upper fan shroud, fan clutch & blade assembly. This allows access to the crank shaft in order to rotate the engine.
Step 2. Rotate the engine clockwise using a 1/2in drive ratchet with appropriate socket. Continue rotating until cam lobes on #1 intake cam lobes are pointing straight up.
Step 3. Use the feeler gauge to check clearances between the back side of the cam lobe and the rocker arm. Ideal clearance would be .008 in. (To confirm you can use a .007 in. blade which should fit easily, and a .009 in. which should not fit.
Step 4. Rotate the motor so that cylinder #2 cam lobes are straight up and check clearance, as described in step #3. Repeat all steps on remaining cylinders.
Step 5: Follow the same procedure on the exhaust valves. With the optimum clearance on exhaust valves being .012 in. with a range of .011 in. to .013 in.

Create a chart so that you can document results of each cam lobes measurement. Create a diagram of the valves. One row of 12 for the intake and one row of 12 for the exhaust. write down the measurements of each valve clearance as you proceed.
Looking into the cavity next to the cam shaft on the exhaust side there are small screens that go directly into the crank case.

IMPORTANT: It is necessary to place a shop towel into this area, and into the spark plug hole to prevent the shims from accidentally falling into the holes.

To Make the Adjustments:

Step 1. Remove the retaining clip over the rocker shaft that keep the shims (pucks) in position, and set it aside.
Step 2. Now it is necessary to move the rocker over to one side with a long flat head screwdriver.
Step 3. Moving it away from the cam lobe and from underneath the valve.

Step 4. With a magnetic pick-up tool, remove the puck out of the top of the valve.
Step 5. Measure the original shim out of the vehicle, and determin if the shim needs to be larger, or smaller to create the ideal clearance. (i.e. The original puck is thirteen thousanths, so it will be replaced with a fifteen thousanths of an inch shim to come within specifications needed for the valve to operate correctly.
Step 6. Use a small amount of assembly lube on the shim to keep it in place on the valve stem. The assembly lube will hold the shim in place after installation.
Step 7. Confirm the shim is seated properly using a small flat blade screwdriver.
Step 8. Now. with feeler gauges check that the clearances are correct.
Step 9. Finally, replace the rocker and retainer to their original position.