Clearances between camshaft lobes and valve lifters (Audi 100 C3)

Clearances between camshaft lobes and valve tappets (engines of DR and DS models produced before September 1985.) are adjusted using adjusting washers, which are made with a thickness of 3.0 to 4.25 mm with a step of 0.05 mm. The thickness is written on one side of the washer. The clearances on a cold engine (at a coolant temperature of (20±50)°C should be for the intake valves (0.20±0.05) mm, for the exhaust (0.40±0.05) mm. It is necessary to adjust the clearances after grinding and polishing the valves after installing a new camshaft. In these cases, after 1000 km of run, re-check and, if necessary, adjust the clearances in the valves.

Adjustment

1. Remove the cylinder head cover.

2. Turn the crankshaft so that the camshaft lobes on the cylinder being checked face up. Use a feeler gauge to check the clearance between the cam and the tappet and record the result. Check the valve clearances on all other cylinders in the same way. Counting from the camshaft drive, valves No.1, 3, 6, 8 are exhaust valves, and valves No.2, 4, 5, 7 are intake valves.

3. If the gap exceeds the permissible value, it is necessary to replace the adjusting washer. To do this, set the piston to TDC of the compression stroke (both valves are closed), using a suitable tool, press and retract the plunger until the adjusting washer can be removed. Each plunger has two notches on the top to facilitate removal of the washer.

4. Measure the thickness of the washer required to set the nominal clearance.

5. Install new adjusting washers, then install the cylinder head cover and upper camshaft drive cover with new gaskets.

6. If the adjusting washers are not worn or damaged when removed, they can be reused.

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