BMW E34 M30 valve clearance and rocker arms
What is the E34 M30 engine's valve clearance?
The specification is 0.30 mm for both intake and exhaust valves, measured on a cold engine. With a worn camshaft and rockers, 0.25 mm can be used because of the rattle. The gap is measured between the camshaft and the rocker, so it is slightly larger than the gap between the valve and the lifter. The adjustment is worth doing about every 20,000 km.
How are the M30 valves adjusted?
1. The coolant temperature must be below +35 °C. 2. Turn the crankshaft from the crankshaft bolt with a large socket or by pushing the car in gear. 3. Adjust a valve only when it is closed, one cylinder at a time in firing order. 4. The adjustment is made with an eccentric and locked with a bolt and nut. 5. Go round again to check.
Why do the M30 rocker arms break and how are they replaced?
The rockers usually break from old age and metal fatigue, especially if the engine is revved close to the red zone. Replace all the rockers at once. On the M30, removing the rocker shaft requires lifting the cover together with the intake manifold. After replacement, check the camshaft timing: if it is wrong, the engine runs roughly.