Ford Focus>> Engines>> Compression measurement>> Norms of a compression of engines

Norm of a compression
1,4 l of Zetec-SE                 
1,6 l of Zetec-SE                 
1,8 l of Zetec-E                   
2,0 l of Zetec-E                   
1,8 l of Endura-Turbodiesel
1,8 l of Endura-DI-Turbodiesel
12-14 kPas
12-14 kPas
12-14 kPas
12-14 kPas
28-34 kPas
28-34 kPas

Maximum permissible value of size of a compression for petrol engines makes 10 kPas, for diesel engines — 24 kPas.
If you have the necessary equipment, can measure a compression independently, however for this purpose you will need the assistant who will turn a cranked shaft a starter. For a start unscrew all spark plugs from a head of the block and be convinced that the valve are correctly exposed. During compression check on the petrol engine your assistant should press an accelerator and coupling pedal completely. At check of the diesel engine to press a pedal of an accelerator it is not necessary.
Start to check with the 1st cylinder and further act on an operating procedure of cylinders. At check define turns of a cranked shaft after which the maximum value of a compression will be established. Smooth increase of pressure in cylinders testifies to a good condition of tsilindroporshnevy group. By experience, on the engine in a good condition the highest value of pressure is noted after 6 — 8 scrollings of a cranked shaft.
Before starting to measure a compression, be convinced that the starter is in a good condition and the storage battery is completely charged. However it is better to entrust this work to the expert, on a difference of sizes of a compression in cylinders and nature of noise it can reveal the following malfunctions:
- noise in an inlet collector — a leaky prileganiye of the inlet valve to a saddle;
- noise from an open maslonalivny mouth or a measuring instrument of level of oil — worn-out walls of cylinders or a crack of a head of the block;
- noise from a final collector — leaky final valves.
If the size of a compression received as a result of measurements is less than norm, try to add a little engine oil in openings under spark plugs (openings under nozzles for a diesel engine) and repeat measurement. It will allow to reduce a gap between the piston and the cylinder. If value does not change — pressure in the cylinder as a result of a leaky prileganiye of valves to saddles or damage of laying of a head. If the size of a compression increased, it indicates wear of piston rings or working surfaces of cylinders.
Measurement of a compression carry out in the following order:
- warm up the engine to working temperature, gaps between moving details as a result will get out;
- disconnect ignition (the contact socket 15), remove from spark plugs tips of wires and turn out all spark plugs;
- brake the car the parking brake, establish the transmission lever in neutral situation. Your assistant should press a pedal of coupling and an accelerator pedal;
- insert a rubber cone of a measuring instrument of a compression into an opening for a spark plug (for a diesel engine this opening for nozzles) the 1st cylinder, if necessary can use an adapter;
- further your assistant scrolls a cranked shaft from 6 to 8 turns to receive the greatest size of a compression;

Fig. 164. The rubber cone of the device for a compression should close an opening under a spark plug

Fig. 165. Device indicators for compression measurement

- write down the received result. Repeat measurements for other cylinders (fig. 164 and 165) .