2.2.9. Cleaning and check of a condition of a head of cylinders and components

Careful cleaning of a head (heads) of cylinders and the related components of the valve with the subsequent detailed check of a state will allow to define what amount of works with valves should be executed at capital repairs of the engine.

If the engine tested a strong overheat, then the head of cylinders is probably bent (watch item 4).



  1. Remove with a scraper from the condensed surfaces of a head of cylinders, the inlet pipeline and a final collector all remains of old laying and a sealing compound. Observe extra care not to damage a head of cylinders. In shops of auto parts it is possible to buy special solvents for removal of laying.
  2. Remove from channels of cooling everything sedimentation.
  3. Rigid brush clean various openings to remove sedimentation which could appear in them.
  4. For removal of corrosion and carving sealant which can be present at carving openings clean them taps of the corresponding size. If compressed air is available, after this operation clear with its help openings of garbage.

When using compressed air apply goggles.

  1. Clear solvent a head of cylinders and carefully dry. Compressed air will accelerate process of drying and will provide purity of openings and deepenings.

There are chemical means for removal of a deposit and they can be very useful when cleaning heads of cylinders and components of knots of valves. However, these means very aggressive and them should be applied with care. Follow instructions on their packings.

  1. Clear solvent shaft yokes/yokes/pushers, springs, springs of valves, holders and crackers, and then carefully dry them. Not to mix components of valves, clear valves in turn.

Do not clear M40 engine hydropushers; leave them completely shipped in oil.

  1. Remove a scraper from valves everything sedimentation, and then remove with an electric brush from heads and cores of valves a deposit. Again track that components of valves were not mixed.

Check of a state

Before making decision on need of works for a mechanical workshop be convinced that all specified checks of a state are executed. Make the list of checks.

Head of cylinders


  1. Carefully examine a head regarding cracks, traces of leakage of a cooler and other damages. At detection of cracks address for consultation in a mechanical workshop. If repair is impossible, it is necessary to get a new head of cylinders.
  1. By means of the measuring instrument of planeness and probes check existence of a curvature the condensed laying of a surface of a head. If curvature exceeds the limit given in the Size table and adjusting data at the end of the Management, then it is possible to grind it in a mechanical workshop provided that thickness of a head will not be less admissible.
  1. Examine saddles of valves of each combustion chamber. If they have considerable dents, cracks or progara, then the head will demand the service which is going beyond opportunities of a house workshop.
  1. Check a gap between a core of the valve and a guide, having measured by the dial indicator a side deviation of a core. The valve has to be in a guide and at the height about 2 mm over a saddle. The full deviation of a core of the valve measured by the indicator should be divided into two to receive the valid value of a gap. If after that there are doubts concerning a condition of the directing valves, then they should be checked in a mechanical workshop (the price of this service is minimum).



  1. Attentively check the surface of each valve in search of uneven wear, deformation, cracks, dents and zones of an obgoraniye. You will check a valve core regarding attrition, and a core neck - for existence of cracks. Rotate the valve and check existence of a noticeable curvature. Check existence on the end of a core of dents and excessive wear. Existence of any of these defects indicates the need of service of valves as it is described in the Section Service of Valves.
1 — the End of the valve
2 — the Flute under crackers
3 — the Core (the worn most out part)
4 — the Core (the worn most out part)
5 — a valve Facet
6 — the Eminence
  1. Measure the size of an eminence of each valve. The valve with smaller, than is required, an eminence, is subject to replacement

Components of valves


  1. Check wear on the ends of all springs. Before deciding to use springs in the restored engine, it is necessary to check their rigidity (for this check send springs to a mechanical workshop) by means of special adaptation.
  1. Establish each spring on a plain surface and check their vertical position. If any of springs is bent or warped or, perhaps, has the broken round, replace springs.
  1. Check holders of springs and crackers for existence of obvious wear tracks and cracks. Any suspicious details should be replaced, otherwise, if they fail during the operation of the engine, then there will be considerable damages.

Yokes (M10, M20 and M30 engines)

Yokes of final valves are most subject to wear and they should be checked with special care.


  1. Check yokes regarding excessive wear on the ends which contact to a core of the valve and the camshaft.
  1. Check a radial gap (watch the Section Dismantling of a Head of Cylinders). If he is too great, then either the yoke plug, or a shaft (or both) are worn-out. For definition what element is more worn-out, shift on some distance a yoke on a shaft and again measure a radial gap. If the gap conforms to requirements now, then probably the shaft is the most worn-out component. If the gap does not conform to requirements, then plugs of yokes are subject to replacement.

Shaft of yokes (M10, M20 and M30 engines)

Check shaft for existence of zadir, excessive wear and other damages. The surfaces of contact of yokes with shaft have to be smooth. If on border of contact of a yoke with shaft there is a ledge, then the shaft is probably worn-out.

Hydropushers (M40 engine)


  1. Check existence of wear, zadir and dents on pushers where they contact from the ends of cores of valves and fingers. If there is a considerable wear of pushers and the camshaft, then it is necessary to buy the new camshaft together with pushers.
  2. Similarly check hydropushers where they contact to wells in a head of cylinders, on existence of wear, zadir and dents. Sometimes hydropushers create noise during the work and demand replacement, and it becomes noticeable during the operation of the engine. To find internal damage or wear of a hydropusher when it is removed, quite difficult; in case of doubts, it is necessary to establish a set of new hydropushers.



  1. Check camshaft necks (the round surfaces of sliding) and cams for existence of zadir, dents, chips and excessive wear. Measure by a micrometer height of each inlet and final cam. Compare height of all inlet and final cams. If results of measurements on all inlet or final cams differ more, than on 0:08 mm or if on the camshaft any signs of wear are found, then replace the camshaft.
  2. Check a condition of surfaces of bearings of sliding in a head of cylinders for existence of zadir and other damages. If the surfaces of bearings have teases or are damaged, then usually make replacement of a head of cylinders as bearings are the processed surfaces in a head of cylinders.

Mechanical workshop (in particular, specializing in BMW) or office of the dealer can offer option alternative to replacement of a head of cylinders if the only problem are insignificant scratches of surfaces of bearings of the camshaft.

  1. Measure by a micrometer of a neck of the camshaft and write down results of measurements.
  1. - a nutromer measure by the telescopic measuring instrument or a micrometer in a head of cylinders diameters of bearings of the camshaft (on the M40 engine previously establish covers of bearings). For obtaining size of a lubricant gap subtract the internal diameter of the corresponding bearing from the size of a neck of the camshaft. Compare a lubricant gap to the value given in the Size table and adjusting data at the end of the Management. If it does not correspond, then the new head of cylinders and/or the new camshaft will be required.

Before installation of a new head of cylinders check former in a mechanical workshop (especially, in specializing in BMW). Perhaps they will be able to restore it.