3.24. Check and adjustment of valvate gaps on the diesel engine

For compensation of thermal expansions in the valvate mechanism there has to be a certain gap.

At too small gap gas distribution phases change, compression process worsens, engine capacity decreases, operation of the engine becomes uneven. In extreme cases valves can be deformed or burn to saddles.

At excessively big gap there are mechanical noise, gas distribution phases, owing to too short time of opening of valves and, therefore, bad filling of cylinders change, engine capacity decreases, the engine works unevenly.

Adjustment of valvate gaps can bring benefit only in that case when valves are ground well in, I am absent inadmissible side plays in their guides, and the ends of cores of valves are not hammered.

Valvate gaps should be regulated within carrying out maintenance, after repair or in the presence of noise in operation of the valvate mechanism.

Valvate gaps should be checked and regulated on the cooled-down engine i.e. when its temperature is equal to ambient temperature.



  1. Uncover a head of cylinders.
  2. Install the piston of the first cylinder in the provision of VMT (see the Head Dvigateli).
  3. When finding the piston of the first cylinder in VMT the provision of cams of the camshaft has the appearance shown (cams do not concern valves of the first cylinder).

The provision of cams of the camshaft when finding the piston of the first cylinder in VMT

  1. Before check of valvate gaps check reliability of tightening of nuts of fastening of covers of basic bearings of the camshaft. If necessary tighten nuts with effort of 25 Nanometers.

Check of effort of tightening of nuts of fastening of covers of basic bearings

  1. Insert the probe between a cam of the camshaft and an adjusting washer and check a gap in compliance with requirements of Specifications in the Head Nastroyki and routine maintenance of the car.
  2. The probe has to be involved as if, otherwise the valvate gap demands adjustment.
  3. Mark the provision of a pulley of a bent shaft opposite to VMT tag. Turn a bent shaft half way in the direction of rotation of the engine. In the provision of VMT there is the following piston now. According to the sequence of ignition 1-3-4-2, it is the third cylinder. Numbers of cylinders go one after another from the first on the fourth. The cylinder 1 is at a pulley of a gear belt. Check gaps in a way described above. Then turn a bent shaft for a half-turn and check a valvate gap of cylinders 4 and 2.
  4. In need of adjustment of a valvate gap change probe thickness until true value of a gap is received. Write down the received value.
  5. Establish a cover of a head of cylinders with new laying and tighten bolts of its fastening with effort of 8 Nanometers.



  1. Turn a bent shaft so that the camshaft cam top over the adjustable valve was turned up.

Installation of the camshaft in situation for adjustment of a valvate gap

  1. Turn a valve pusher so that the groove of a pusher was turned forward.
  2. The valvate gap is regulated by selection of adjusting washers. For this purpose press a pusher special OPEL-KM-650 adaptation.

Pressing of a pusher special tool

  1. Take out an adjusting washer from a pusher and by means of a magnet.
  2. Determine thickness of the established adjusting washer by a micrometer and write down result of measurement. Thickness of a washer has to be engraved on its lower party.
  3. Calculate thickness of a new adjusting washer on a formula N = T (A - S) where N - thickness of a new adjusting washer, T - thickness of the removed adjusting washer, And - the measured value of a valvate gap, and S - demanded by Specifications (in the Head Nastroyki and routine maintenance of the car) value of a valvate gap.

Adjusting washers can be applied, as a rule, repeatedly, clearly visible wear tracks will not appear yet. If marking of thickness of a washer is not visible any more, then the washer should not be applied further.

  1. Moisten new adjusting in motive oil and establish a washer by marking down.
  2. In the way described above adjust all valvate gaps.
  3. In conclusion double-check valvate gaps.