We check and adjust the valve clearances when repairing the cylinder head, when a loud knock appears in the upper part of the engine.

Checking and adjustment is carried out at an engine coolant temperature below 60˚ C.

Remove the cylinder head cover

Checking and adjusting valve clearance Cummins ISF3.8

Rotate the crankshaft and set the piston of the first cylinder to the TDC of the compression stroke.

Checking and adjusting valve clearances Cummins ISF3.8

Checking the valve clearance:

  • - first inlet;
  • - first graduation;
  • - second inlet;
  • - the third graduation.

Checking and adjusting valve clearances Cummins ISF3.8

With a properly adjusted gap, the feeler gauge passes between the rocker bridge and the rocker seat with little resistance.

Nominal clearance:

  • - inlet valve 0.280 - 0.381 mm
  • - exhaust valve 0.530 - 0.630 mm

If the gap is different from the nominal, unscrew the lock nut and adjust it with the adjusting screw.

Tighten the locknut and check the gap again. Nominal clearance (when adjusted):

  • - inlet valve 0.33 mm
  • - exhaust valve 0.58 mm

Tightening torque 24 Nm

Rotate the crankshaft 360˚

Measure the gaps in the drive of the remaining valves:

  • - second graduation;
  • - third inlet;
  • - fourth graduation;
  • - fourth inlet.

If necessary, adjust the gaps

Install all parts in reverse order.