3.8. Check of work and replacement of the sensor of the measuring instrument of temperature of a cooler

Before work the engine has to cool down completely.

The system of indication of temperature of a cooler consists of the measuring instrument of temperature which is built in in an instrument guard and the block of the sensor of temperature of the cooler which is usually located on a thermostat casing (see an illustration). On some cars more than one sensor are installed, but is only one of them used by temperature measuring instrument. On M40 engines the block of the sensor is installed on the left back side of a head of cylinders.

If there are suspicions that the measuring instrument works incorrectly, first of all check cooler level in system. Make sure that conducting between the sensor and the measuring instrument is not damaged, and that safety locks as it should be. (If you suspect that it is faulty as well the fuel level measuring instrument, then a problem almost for certain in an instrument guard or its conducting).

Before check of an electric chain cope with the corresponding schematic diagrams (see the Head Sistem of onboard electric equipment). If the sensor block just grounds a chain, make check, having grounded the wire connected to the sensor at the included ignition (but without starting the engine, for safety). If the measuring instrument at the same time reads off scale, replace the sensor block. If the measuring instrument does not react, then either it, or its conducting are faulty. Where the block of the sensor has two plugs, check a chain, having measured block resistance. In time of writing of this manual there were no exact figures, but normal resistance has to make approximately from several hundred to several thousand Ohms (depending on temperature). The indications equal to zero (at short circuit) or infinity (at the opened chain) will indicate the faulty block of the sensor.

Do not ground a wire more, than for couple of seconds, differently it is possible to damage the measuring instrument.

If it is necessary to install the new block of the sensor, at first let's the engine cool down completely. At removal of the sensor a little cooler therefore or be going to bring together him will flow out, or keep the new block in readiness to establish it right after removal old. Disconnect conducting, then give screws and remove the old block of the sensor from the engine then establish new. Apply sealant on carvings. Connect conducting and in conclusion check cooler level.