How to measure the tightness of the drive train in a Mazda 3 1.6 D

The following text will focus on the pressure measurement process on a Mazda 3 1.6 D 109 hp car manufactured in 2008 with a mileage of 210000 km. The vehicle has been replaced twice turbocharger and in fact the second replacement became the reason for a more detailed look at the causes of the failure. One of the tasks the service technicians had to perform to thoroughly investigate the condition of the driveline was to measuring system pressure and leaks.

We start by taking it in turns to replace one of the injectors we place an adapter to measure the pressure and tightness of the entire system. The adapter is also used to measure compression.

Preparation for the test and calibration of the measuring instrument

Once all components are fitted, the output pressure to the instrument is between 6 and 16 Bar. We set the top dead centre for the fourth cylinder by twisting and maxing out the cylinder. We then calibrate the instrument. Calibration involves setting the 100%, placing the cable on the adapter and taking a percentage reading.

Correct measurement and reading of values

The meter pointer stopping at red indicates that the values are incorrect. Indications at 10% are unacceptable. Acceptable standards are values between 60 and 100%. Note that a value at the 100% level is unattainable, but fully operational drivetrains are capable of achieving results up to 85%.
We then take measurements separately on each cylinder. This measurement gives us the opportunity to check the condition of the head gasket and its tightness. This allows us to answer the question of whether the head gasket has damage. In the case of a result of 10%, the resulting diagnosis indicates the following leaking gasket or crack in engine block.

Finding the causes of engine failure and deterioration

Two turbocharger failures and oil accumulating in the system led to the accumulation of excessive carbon build-up and subsequent oil sintering on the valve seats. This was the cause of the system's lack of tightness. The valves no longer close. As a result, exhaust gases leak into the cooling system. In this case, a carbon dioxide test should be carried out in the cooling system.

Actions to restore the efficiency of the system

This gives us the opportunity to answer the question of whether the tightness between the head and cylinders is correct. In the case of the Mazda described, it is possible to speak of excessive engine wear. The final verification stage to answer all questions is to pull the head off. The condition of the cylinders is also checked using an inspection camera.

Take a look at the video showing the entire diagnostic process:

The entire diagnosis was carried out in Bosch Diesel Turbo-Tec Centre.