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Autopapyrus · Mazda Bongo 2.0 Diesel RF (1993)
https://autopapyrus.com/guides/mazda/bongo/checking-and-adjusting-valve-lash/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Mazda Bongo 2.0 Diesel RF (1993): Checking and Adjusting Valve Lash

The RF 2.0 diesel engine (SOHC, 8 valves) requires periodic valve lash checks and adjustments every 80,000-100,000 km (50,000-62,000 mi). The valvetrain uses direct valve actuation through followers and adjusting screws. Adjustment must be done on a cold engine (oil temperature no higher than 40°C (104°F)).

Difficulty: Medium Time: 2-3 hours Steps: 8 Tools: Feeler gauge set 0.05-0.50 mm, 10/12/14 mm wrenches, flat-head screwdriver, torque wrench, special adjusting screw wrench (if available)

Part

  • 🔩 Valve cover gasket (if replacement is needed)

Step by step

8 steps
  1. Remove the valve cover: disconnect the crankcase ventilation hoses, remove the 8-10 mounting bolts around the perimeter, and carefully lift the cover straight up (do not damage the gasket).
  2. Turn the crankshaft clockwise until the No. 1 cylinder TDC marks line up: the mark on the crankshaft pulley is opposite the pointer on the front cover, and the camshaft mark is at the top.
  3. Check the valve lash on the No. 1 and No. 4 cylinders. Insert the feeler gauge between the camshaft lobe and the follower: intake 0.20-0.30 mm (nominal 0.25 mm), exhaust 0.30-0.40 mm (nominal 0.35 mm). The gauge should slide through with light resistance.
  4. If the lash is out of spec, loosen the adjusting screw locknut with a 12 mm wrench while holding the screw with a screwdriver or the special wrench. Turn the screw until the feeler gauge shows the correct lash, tighten the locknut to 12-15 N·m (9-11 lb-ft), and recheck the lash (the screw can shift as you tighten it).
  5. Turn the crankshaft 180° (half a turn). The camshaft mark now points left. Check and adjust the valves on the No. 2 and No. 3 cylinders the same way.
  6. Turn the crankshaft another 180°. The camshaft mark is now at the bottom. Check and adjust the remaining valves.
  7. Turn the crankshaft two full revolutions and recheck all the lash settings to make sure the adjustment has not changed.
  8. Wipe the mating surfaces of the cylinder head and the cover clean of oil. Install the cover with a new gasket (or the old one if it is intact), and tighten the bolts in a crisscross pattern to 8-10 N·m (6-7 lb-ft).

Common mistakes and warnings

  • Incorrect lash leads to power loss and valvetrain damage: too little lash risks burned valves, and too much causes ticking and accelerated wear. Work only on a cold engine, because hot measurements will give incorrect values. If the lash is far from nominal or the screws do not have enough adjustment range, the followers need replacing or the camshaft lobes need to be checked for wear.