Subaru Legacy/Outback

1999-2003 of release

Repair and operation of the car

Subaru of Legasi, Autbek
+ Cars Subaru Legacy, Outback
+ Operation manual
+ Routine maintenance
- Engine
   Check of compression pressure in cylinders and tightness of the block
   Diagnostics of a condition of the engine with use of the vacuum gage
   The engine lubrication system - the general information
   + the repair Procedures which are not connected with extraction of the engine from the car - four-cylinder engines
   + the repair Procedures which are not connected with extraction of the engine from the car - six-cylinder engines
   + General and capital repairs of engines
+ Cooling systems, heating
+ Power supply system and release
+ Electric equipment of the engine
+ Manual box and differential
+ Automatic transmission
+ Coupling
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment


Check of compression pressure in cylinders and tightness of the block

Check of compression pressure


 When using a kompressometr of the rolled type length of carving part of the nozzle rolled in a candle opening should not exceed 18 mm!

When carrying out measurements be careful, - do not burn about the warmed engine surfaces!

1. Results of check of compression pressure in cylinders allow to define the general condition of the components located from outer sides of semi-blocks (pistons, piston rings, valves, laying of heads of cylinders and so forth) and qualitatively to estimate degree of their wear. That is especially important, the analysis of information received as a result of check allows to narrow a range of the possible reasons of falling of a compression in cylinders, rather precisely having tied refusal to violations of functioning of quite concrete components, whether it be piston rings, valves, their saddles or laying of a head of cylinders

 The engine has to be heated-up up to the normal working temperature, and the battery is completely charged.

2. Make sure of completeness of charging of the battery.
3. Warm up the engine up to the normal working temperature, then turn the ignition switch in the situation OFF.
4. Dump fuel pressure (see the Head of the Power supply system and release).
5. Begin with a clearing of candle niches (blow them compressed air as which source in this case the ordinary bicycle pump perfectly will approach), - the main task is prevention of hit of garbage in cylinders during performance of measurements.
6. Turn out from the engine all spark plugs (see the Head Routine maintenance).
7. Disconnect an electrical wiring from fuel injection injectors.
8. Record a butterfly valve in completely open situation.
9. Check serviceability of functioning of a starter.
10. Connect kompressometr to a candle opening of the first cylinder.

 When using a kompressometr with the rolled nozzle length of carving part of the last has to make not more long than 18 mm!

11. Turn the engine a starter at least on seven turns and consider the indication of the measuring instrument. On the serviceable engine pressure has to increase quickly enough. The low pressure in the first step which is followed by its gradual increase in the subsequent speaks about wear of piston rings. If at a further provorachivaniye of a shaft pressure does not rise, it can be regarded as the evidence of leakages of valves or violation of tightness of laying of a head of cylinders (also the probability of existence of cracks in a head is not excluded). The congestion of deposits on working facets of plates of valves can also lead to decrease in compression pressure. Write down the maximum indication of a kompressometr at the steady provision of the index. Take measurements, at least, twice.

12. Repeat procedure for the remained engine cylinders. Compare results to standard requirements (see Specifications).
13. At excessively low results of measurement, fill in in each of cylinders through a candle opening of a little motive oil (two-three teaspoons) and repeat check.
14. If addition of oil leads to increase of pressure, it speaks about wear of piston rings. If the compression does not increase, leakages of valves or violation of tightness of laying of a head are the reason of its decrease. Leakages of valves can be connected with a burn-out of their saddles, either a deformation/burn-out or mechanical damages of working facets.
15. If pressure of compression is equally underestimated in two next cylinders, with high degree of probability it is possible to speak about violation of integrity of laying of a head within its crossing point between these cylinders. Presence of cooling liquid at motive oil will confirm this assumption.
16. If pressure in one of cylinders is about 20% lower, than in other and it is followed by violation of stability of turns of idling, it is necessary to estimate degree of wear of cams of the drive of the corresponding valves on a camshaft.
17. Unusual overestimate of compression pressure usually is a consequence of an excessive nagaroobrazovaniye in combustion chambers. In this case the head of cylinders has to be removed for the purpose of carrying out decarbonization.
18. At excessively low results of measurements, and also in case of violation of uniformity of distribution of pressure between cylinders it will be useful to hold testing of the engine for leaks in the conditions of a workshop of car service. Such check will allow to define precisely a source of leak and to estimate degree of its gravity.
19. Establish into place safety locks and make on the car a short trip for the purpose of restoration of the adjusting parameters which are written down in memory of the processor.

Check of the block on leaks


1. During this check are defined exit speed from cylinders of the compressed air pumped in them and directly a place of leaks. This check is alternative to check of a compression. Moreover, from many points of view, it is much more effective as visually leaks simpler to reveal a source, than to comprehend results of measurement of a compression.
2. The equipment necessary for check on leaks, is not among public therefore performance of this check should be entrusted specialists of the service center.