Measuring the compression ratio (Mondeo 3)

1. Before taking measurements, warm up the engine to operating temperature. This will ensure that all moving parts are in working order.
2. Disconnect the ignition (terminal 15) from the terminals, disconnect the spark plug connector and remove all the spark plugs.
3. Set the handbrake, set the gearshift lever to idle, press the clutch and accelerator pedals.
4. Press the rubber cone of the pressure controller to the spark plug hole (in a diesel engine to the injector nozzle) of the first cylinder - use a suitable adapter if necessary.
5. The assistant turns the engine with the starter approximately 6-8 times. Maximum pressure is reached. Important point for carburetor engines: the best filling with fresh fuel mixture (external formation of the mixture) is achieved only when the gas pedal is fully depressed.
6. Read the measurement and write it down. If you have a device with a recorder (data storage device), switch it to the next cylinder.
   
   

7. The rubber cone of the compression tester should tightly close the spark plug hole. At your command, the assistant starts the starter. The starter should be turned until the indicator of the device is in the resting position.

   
   

   Repeat the measurement process on all four cylinders in the row. It is important that the absolute pressure value is the same in all cylinders.

Reducing compression pressure

• in the intake manifold or intake noise muffler - a leaky intake valve.
• from an open radiator or coolant expansion tank - defective cylinder head gasket or cracks in the cylinder head.
• from an open oil filler neck or oil level indicator - worn cylinder walls, cylinder working surfaces or piston rings.
• in the exhaust pipe - a leaky exhaust valve.